9ca071b6e5
Revert CL that updated example for SetUpTestSuite/TearDownTestSuite to initialize static member variables inline. It seems that non-const static data members for some reason still must be initialized out-of-line. PiperOrigin-RevId: 408913846
2380 lines
84 KiB
Markdown
2380 lines
84 KiB
Markdown
# Advanced googletest Topics
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## Introduction
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Now that you have read the [googletest Primer](primer.md) and learned how to
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write tests using googletest, it's time to learn some new tricks. This document
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will show you more assertions as well as how to construct complex failure
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messages, propagate fatal failures, reuse and speed up your test fixtures, and
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use various flags with your tests.
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## More Assertions
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This section covers some less frequently used, but still significant,
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assertions.
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### Explicit Success and Failure
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See [Explicit Success and Failure](reference/assertions.md#success-failure) in
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the Assertions Reference.
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### Exception Assertions
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See [Exception Assertions](reference/assertions.md#exceptions) in the Assertions
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Reference.
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### Predicate Assertions for Better Error Messages
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Even though googletest has a rich set of assertions, they can never be complete,
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as it's impossible (nor a good idea) to anticipate all scenarios a user might
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run into. Therefore, sometimes a user has to use `EXPECT_TRUE()` to check a
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complex expression, for lack of a better macro. This has the problem of not
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showing you the values of the parts of the expression, making it hard to
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understand what went wrong. As a workaround, some users choose to construct the
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failure message by themselves, streaming it into `EXPECT_TRUE()`. However, this
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is awkward especially when the expression has side-effects or is expensive to
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evaluate.
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googletest gives you three different options to solve this problem:
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#### Using an Existing Boolean Function
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If you already have a function or functor that returns `bool` (or a type that
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can be implicitly converted to `bool`), you can use it in a *predicate
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assertion* to get the function arguments printed for free. See
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[`EXPECT_PRED*`](reference/assertions.md#EXPECT_PRED) in the Assertions
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Reference for details.
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#### Using a Function That Returns an AssertionResult
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While `EXPECT_PRED*()` and friends are handy for a quick job, the syntax is not
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satisfactory: you have to use different macros for different arities, and it
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feels more like Lisp than C++. The `::testing::AssertionResult` class solves
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this problem.
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An `AssertionResult` object represents the result of an assertion (whether it's
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a success or a failure, and an associated message). You can create an
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`AssertionResult` using one of these factory functions:
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```c++
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namespace testing {
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// Returns an AssertionResult object to indicate that an assertion has
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// succeeded.
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AssertionResult AssertionSuccess();
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// Returns an AssertionResult object to indicate that an assertion has
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// failed.
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AssertionResult AssertionFailure();
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}
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```
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You can then use the `<<` operator to stream messages to the `AssertionResult`
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object.
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To provide more readable messages in Boolean assertions (e.g. `EXPECT_TRUE()`),
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write a predicate function that returns `AssertionResult` instead of `bool`. For
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example, if you define `IsEven()` as:
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```c++
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testing::AssertionResult IsEven(int n) {
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if ((n % 2) == 0)
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return testing::AssertionSuccess();
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else
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return testing::AssertionFailure() << n << " is odd";
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}
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```
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instead of:
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```c++
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bool IsEven(int n) {
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return (n % 2) == 0;
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}
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```
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the failed assertion `EXPECT_TRUE(IsEven(Fib(4)))` will print:
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```none
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Value of: IsEven(Fib(4))
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Actual: false (3 is odd)
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Expected: true
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```
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instead of a more opaque
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```none
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Value of: IsEven(Fib(4))
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Actual: false
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Expected: true
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```
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If you want informative messages in `EXPECT_FALSE` and `ASSERT_FALSE` as well
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(one third of Boolean assertions in the Google code base are negative ones), and
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are fine with making the predicate slower in the success case, you can supply a
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success message:
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```c++
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testing::AssertionResult IsEven(int n) {
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if ((n % 2) == 0)
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return testing::AssertionSuccess() << n << " is even";
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else
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return testing::AssertionFailure() << n << " is odd";
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}
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```
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Then the statement `EXPECT_FALSE(IsEven(Fib(6)))` will print
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```none
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Value of: IsEven(Fib(6))
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Actual: true (8 is even)
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Expected: false
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```
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#### Using a Predicate-Formatter
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If you find the default message generated by
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[`EXPECT_PRED*`](reference/assertions.md#EXPECT_PRED) and
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[`EXPECT_TRUE`](reference/assertions.md#EXPECT_TRUE) unsatisfactory, or some
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arguments to your predicate do not support streaming to `ostream`, you can
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instead use *predicate-formatter assertions* to *fully* customize how the
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message is formatted. See
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[`EXPECT_PRED_FORMAT*`](reference/assertions.md#EXPECT_PRED_FORMAT) in the
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Assertions Reference for details.
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### Floating-Point Comparison
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See [Floating-Point Comparison](reference/assertions.md#floating-point) in the
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Assertions Reference.
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#### Floating-Point Predicate-Format Functions
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Some floating-point operations are useful, but not that often used. In order to
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avoid an explosion of new macros, we provide them as predicate-format functions
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that can be used in the predicate assertion macro
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[`EXPECT_PRED_FORMAT2`](reference/assertions.md#EXPECT_PRED_FORMAT), for
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example:
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```c++
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using ::testing::FloatLE;
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using ::testing::DoubleLE;
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...
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EXPECT_PRED_FORMAT2(FloatLE, val1, val2);
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EXPECT_PRED_FORMAT2(DoubleLE, val1, val2);
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```
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The above code verifies that `val1` is less than, or approximately equal to,
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`val2`.
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### Asserting Using gMock Matchers
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See [`EXPECT_THAT`](reference/assertions.md#EXPECT_THAT) in the Assertions
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Reference.
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### More String Assertions
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(Please read the [previous](#asserting-using-gmock-matchers) section first if
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you haven't.)
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You can use the gMock [string matchers](reference/matchers.md#string-matchers)
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with [`EXPECT_THAT`](reference/assertions.md#EXPECT_THAT) to do more string
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comparison tricks (sub-string, prefix, suffix, regular expression, and etc). For
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example,
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```c++
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using ::testing::HasSubstr;
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using ::testing::MatchesRegex;
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...
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ASSERT_THAT(foo_string, HasSubstr("needle"));
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EXPECT_THAT(bar_string, MatchesRegex("\\w*\\d+"));
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```
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### Windows HRESULT assertions
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See [Windows HRESULT Assertions](reference/assertions.md#HRESULT) in the
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Assertions Reference.
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### Type Assertions
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You can call the function
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```c++
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::testing::StaticAssertTypeEq<T1, T2>();
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```
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to assert that types `T1` and `T2` are the same. The function does nothing if
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the assertion is satisfied. If the types are different, the function call will
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fail to compile, the compiler error message will say that `T1 and T2 are not the
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same type` and most likely (depending on the compiler) show you the actual
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values of `T1` and `T2`. This is mainly useful inside template code.
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**Caveat**: When used inside a member function of a class template or a function
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template, `StaticAssertTypeEq<T1, T2>()` is effective only if the function is
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instantiated. For example, given:
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```c++
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template <typename T> class Foo {
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public:
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void Bar() { testing::StaticAssertTypeEq<int, T>(); }
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};
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```
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the code:
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```c++
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void Test1() { Foo<bool> foo; }
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```
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will not generate a compiler error, as `Foo<bool>::Bar()` is never actually
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instantiated. Instead, you need:
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```c++
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void Test2() { Foo<bool> foo; foo.Bar(); }
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```
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to cause a compiler error.
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### Assertion Placement
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You can use assertions in any C++ function. In particular, it doesn't have to be
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a method of the test fixture class. The one constraint is that assertions that
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generate a fatal failure (`FAIL*` and `ASSERT_*`) can only be used in
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void-returning functions. This is a consequence of Google's not using
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exceptions. By placing it in a non-void function you'll get a confusing compile
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error like `"error: void value not ignored as it ought to be"` or `"cannot
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initialize return object of type 'bool' with an rvalue of type 'void'"` or
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`"error: no viable conversion from 'void' to 'string'"`.
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If you need to use fatal assertions in a function that returns non-void, one
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option is to make the function return the value in an out parameter instead. For
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example, you can rewrite `T2 Foo(T1 x)` to `void Foo(T1 x, T2* result)`. You
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need to make sure that `*result` contains some sensible value even when the
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function returns prematurely. As the function now returns `void`, you can use
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any assertion inside of it.
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If changing the function's type is not an option, you should just use assertions
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that generate non-fatal failures, such as `ADD_FAILURE*` and `EXPECT_*`.
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{: .callout .note}
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NOTE: Constructors and destructors are not considered void-returning functions,
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according to the C++ language specification, and so you may not use fatal
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assertions in them; you'll get a compilation error if you try. Instead, either
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call `abort` and crash the entire test executable, or put the fatal assertion in
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a `SetUp`/`TearDown` function; see
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[constructor/destructor vs. `SetUp`/`TearDown`](faq.md#CtorVsSetUp)
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{: .callout .warning}
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WARNING: A fatal assertion in a helper function (private void-returning method)
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called from a constructor or destructor does not terminate the current test, as
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your intuition might suggest: it merely returns from the constructor or
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destructor early, possibly leaving your object in a partially-constructed or
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partially-destructed state! You almost certainly want to `abort` or use
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`SetUp`/`TearDown` instead.
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## Skipping test execution
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Related to the assertions `SUCCEED()` and `FAIL()`, you can prevent further test
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execution at runtime with the `GTEST_SKIP()` macro. This is useful when you need
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to check for preconditions of the system under test during runtime and skip
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tests in a meaningful way.
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`GTEST_SKIP()` can be used in individual test cases or in the `SetUp()` methods
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of classes derived from either `::testing::Environment` or `::testing::Test`.
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For example:
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```c++
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TEST(SkipTest, DoesSkip) {
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GTEST_SKIP() << "Skipping single test";
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EXPECT_EQ(0, 1); // Won't fail; it won't be executed
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}
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class SkipFixture : public ::testing::Test {
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protected:
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void SetUp() override {
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GTEST_SKIP() << "Skipping all tests for this fixture";
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}
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};
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// Tests for SkipFixture won't be executed.
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TEST_F(SkipFixture, SkipsOneTest) {
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EXPECT_EQ(5, 7); // Won't fail
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}
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```
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As with assertion macros, you can stream a custom message into `GTEST_SKIP()`.
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## Teaching googletest How to Print Your Values
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When a test assertion such as `EXPECT_EQ` fails, googletest prints the argument
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values to help you debug. It does this using a user-extensible value printer.
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This printer knows how to print built-in C++ types, native arrays, STL
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containers, and any type that supports the `<<` operator. For other types, it
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prints the raw bytes in the value and hopes that you the user can figure it out.
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As mentioned earlier, the printer is *extensible*. That means you can teach it
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to do a better job at printing your particular type than to dump the bytes. To
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do that, define `<<` for your type:
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```c++
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#include <ostream>
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namespace foo {
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class Bar { // We want googletest to be able to print instances of this.
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...
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// Create a free inline friend function.
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friend std::ostream& operator<<(std::ostream& os, const Bar& bar) {
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return os << bar.DebugString(); // whatever needed to print bar to os
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}
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};
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// If you can't declare the function in the class it's important that the
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// << operator is defined in the SAME namespace that defines Bar. C++'s look-up
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// rules rely on that.
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std::ostream& operator<<(std::ostream& os, const Bar& bar) {
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return os << bar.DebugString(); // whatever needed to print bar to os
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}
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} // namespace foo
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```
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Sometimes, this might not be an option: your team may consider it bad style to
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have a `<<` operator for `Bar`, or `Bar` may already have a `<<` operator that
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doesn't do what you want (and you cannot change it). If so, you can instead
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define a `PrintTo()` function like this:
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```c++
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#include <ostream>
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namespace foo {
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class Bar {
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...
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friend void PrintTo(const Bar& bar, std::ostream* os) {
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*os << bar.DebugString(); // whatever needed to print bar to os
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}
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};
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// If you can't declare the function in the class it's important that PrintTo()
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// is defined in the SAME namespace that defines Bar. C++'s look-up rules rely
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// on that.
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void PrintTo(const Bar& bar, std::ostream* os) {
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*os << bar.DebugString(); // whatever needed to print bar to os
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}
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} // namespace foo
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```
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If you have defined both `<<` and `PrintTo()`, the latter will be used when
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googletest is concerned. This allows you to customize how the value appears in
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googletest's output without affecting code that relies on the behavior of its
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`<<` operator.
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If you want to print a value `x` using googletest's value printer yourself, just
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call `::testing::PrintToString(x)`, which returns an `std::string`:
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```c++
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vector<pair<Bar, int> > bar_ints = GetBarIntVector();
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EXPECT_TRUE(IsCorrectBarIntVector(bar_ints))
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<< "bar_ints = " << testing::PrintToString(bar_ints);
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```
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## Death Tests
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In many applications, there are assertions that can cause application failure if
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a condition is not met. These consistency checks, which ensure that the program
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is in a known good state, are there to fail at the earliest possible time after
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some program state is corrupted. If the assertion checks the wrong condition,
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then the program may proceed in an erroneous state, which could lead to memory
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corruption, security holes, or worse. Hence it is vitally important to test that
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such assertion statements work as expected.
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Since these precondition checks cause the processes to die, we call such tests
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_death tests_. More generally, any test that checks that a program terminates
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(except by throwing an exception) in an expected fashion is also a death test.
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Note that if a piece of code throws an exception, we don't consider it "death"
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for the purpose of death tests, as the caller of the code could catch the
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exception and avoid the crash. If you want to verify exceptions thrown by your
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code, see [Exception Assertions](#ExceptionAssertions).
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If you want to test `EXPECT_*()/ASSERT_*()` failures in your test code, see
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["Catching" Failures](#catching-failures).
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### How to Write a Death Test
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GoogleTest provides assertion macros to support death tests. See
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[Death Assertions](reference/assertions.md#death) in the Assertions Reference
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for details.
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To write a death test, simply use one of the macros inside your test function.
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For example,
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```c++
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TEST(MyDeathTest, Foo) {
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// This death test uses a compound statement.
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ASSERT_DEATH({
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int n = 5;
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Foo(&n);
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}, "Error on line .* of Foo()");
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}
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TEST(MyDeathTest, NormalExit) {
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EXPECT_EXIT(NormalExit(), testing::ExitedWithCode(0), "Success");
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}
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TEST(MyDeathTest, KillProcess) {
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EXPECT_EXIT(KillProcess(), testing::KilledBySignal(SIGKILL),
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"Sending myself unblockable signal");
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}
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```
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verifies that:
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* calling `Foo(5)` causes the process to die with the given error message,
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* calling `NormalExit()` causes the process to print `"Success"` to stderr and
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exit with exit code 0, and
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* calling `KillProcess()` kills the process with signal `SIGKILL`.
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The test function body may contain other assertions and statements as well, if
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necessary.
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Note that a death test only cares about three things:
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1. does `statement` abort or exit the process?
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2. (in the case of `ASSERT_EXIT` and `EXPECT_EXIT`) does the exit status
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satisfy `predicate`? Or (in the case of `ASSERT_DEATH` and `EXPECT_DEATH`)
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is the exit status non-zero? And
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3. does the stderr output match `matcher`?
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In particular, if `statement` generates an `ASSERT_*` or `EXPECT_*` failure, it
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will **not** cause the death test to fail, as googletest assertions don't abort
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the process.
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### Death Test Naming
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{: .callout .important}
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IMPORTANT: We strongly recommend you to follow the convention of naming your
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**test suite** (not test) `*DeathTest` when it contains a death test, as
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demonstrated in the above example. The
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[Death Tests And Threads](#death-tests-and-threads) section below explains why.
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If a test fixture class is shared by normal tests and death tests, you can use
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`using` or `typedef` to introduce an alias for the fixture class and avoid
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duplicating its code:
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```c++
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class FooTest : public testing::Test { ... };
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using FooDeathTest = FooTest;
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TEST_F(FooTest, DoesThis) {
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// normal test
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}
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TEST_F(FooDeathTest, DoesThat) {
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// death test
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}
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```
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### Regular Expression Syntax
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On POSIX systems (e.g. Linux, Cygwin, and Mac), googletest uses the
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[POSIX extended regular expression](http://www.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap09.html#tag_09_04)
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syntax. To learn about this syntax, you may want to read this
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[Wikipedia entry](http://en.wikipedia.org/wiki/Regular_expression#POSIX_Extended_Regular_Expressions).
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On Windows, googletest uses its own simple regular expression implementation. It
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lacks many features. For example, we don't support union (`"x|y"`), grouping
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(`"(xy)"`), brackets (`"[xy]"`), and repetition count (`"x{5,7}"`), among
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others. Below is what we do support (`A` denotes a literal character, period
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(`.`), or a single `\\ ` escape sequence; `x` and `y` denote regular
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expressions.):
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Expression | Meaning
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---------- | --------------------------------------------------------------
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`c` | matches any literal character `c`
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`\\d` | matches any decimal digit
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`\\D` | matches any character that's not a decimal digit
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`\\f` | matches `\f`
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`\\n` | matches `\n`
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`\\r` | matches `\r`
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`\\s` | matches any ASCII whitespace, including `\n`
|
|
`\\S` | matches any character that's not a whitespace
|
|
`\\t` | matches `\t`
|
|
`\\v` | matches `\v`
|
|
`\\w` | matches any letter, `_`, or decimal digit
|
|
`\\W` | matches any character that `\\w` doesn't match
|
|
`\\c` | matches any literal character `c`, which must be a punctuation
|
|
`.` | matches any single character except `\n`
|
|
`A?` | matches 0 or 1 occurrences of `A`
|
|
`A*` | matches 0 or many occurrences of `A`
|
|
`A+` | matches 1 or many occurrences of `A`
|
|
`^` | matches the beginning of a string (not that of each line)
|
|
`$` | matches the end of a string (not that of each line)
|
|
`xy` | matches `x` followed by `y`
|
|
|
|
To help you determine which capability is available on your system, googletest
|
|
defines macros to govern which regular expression it is using. The macros are:
|
|
`GTEST_USES_SIMPLE_RE=1` or `GTEST_USES_POSIX_RE=1`. If you want your death
|
|
tests to work in all cases, you can either `#if` on these macros or use the more
|
|
limited syntax only.
|
|
|
|
### How It Works
|
|
|
|
See [Death Assertions](reference/assertions.md#death) in the Assertions
|
|
Reference.
|
|
|
|
### Death Tests And Threads
|
|
|
|
The reason for the two death test styles has to do with thread safety. Due to
|
|
well-known problems with forking in the presence of threads, death tests should
|
|
be run in a single-threaded context. Sometimes, however, it isn't feasible to
|
|
arrange that kind of environment. For example, statically-initialized modules
|
|
may start threads before main is ever reached. Once threads have been created,
|
|
it may be difficult or impossible to clean them up.
|
|
|
|
googletest has three features intended to raise awareness of threading issues.
|
|
|
|
1. A warning is emitted if multiple threads are running when a death test is
|
|
encountered.
|
|
2. Test suites with a name ending in "DeathTest" are run before all other
|
|
tests.
|
|
3. It uses `clone()` instead of `fork()` to spawn the child process on Linux
|
|
(`clone()` is not available on Cygwin and Mac), as `fork()` is more likely
|
|
to cause the child to hang when the parent process has multiple threads.
|
|
|
|
It's perfectly fine to create threads inside a death test statement; they are
|
|
executed in a separate process and cannot affect the parent.
|
|
|
|
### Death Test Styles
|
|
|
|
The "threadsafe" death test style was introduced in order to help mitigate the
|
|
risks of testing in a possibly multithreaded environment. It trades increased
|
|
test execution time (potentially dramatically so) for improved thread safety.
|
|
|
|
The automated testing framework does not set the style flag. You can choose a
|
|
particular style of death tests by setting the flag programmatically:
|
|
|
|
```c++
|
|
GTEST_FLAG_SET(death_test_style, "threadsafe")
|
|
```
|
|
|
|
You can do this in `main()` to set the style for all death tests in the binary,
|
|
or in individual tests. Recall that flags are saved before running each test and
|
|
restored afterwards, so you need not do that yourself. For example:
|
|
|
|
```c++
|
|
int main(int argc, char** argv) {
|
|
testing::InitGoogleTest(&argc, argv);
|
|
GTEST_FLAG_SET(death_test_style, "fast");
|
|
return RUN_ALL_TESTS();
|
|
}
|
|
|
|
TEST(MyDeathTest, TestOne) {
|
|
GTEST_FLAG_SET(death_test_style, "threadsafe");
|
|
// This test is run in the "threadsafe" style:
|
|
ASSERT_DEATH(ThisShouldDie(), "");
|
|
}
|
|
|
|
TEST(MyDeathTest, TestTwo) {
|
|
// This test is run in the "fast" style:
|
|
ASSERT_DEATH(ThisShouldDie(), "");
|
|
}
|
|
```
|
|
|
|
### Caveats
|
|
|
|
The `statement` argument of `ASSERT_EXIT()` can be any valid C++ statement. If
|
|
it leaves the current function via a `return` statement or by throwing an
|
|
exception, the death test is considered to have failed. Some googletest macros
|
|
may return from the current function (e.g. `ASSERT_TRUE()`), so be sure to avoid
|
|
them in `statement`.
|
|
|
|
Since `statement` runs in the child process, any in-memory side effect (e.g.
|
|
modifying a variable, releasing memory, etc) it causes will *not* be observable
|
|
in the parent process. In particular, if you release memory in a death test,
|
|
your program will fail the heap check as the parent process will never see the
|
|
memory reclaimed. To solve this problem, you can
|
|
|
|
1. try not to free memory in a death test;
|
|
2. free the memory again in the parent process; or
|
|
3. do not use the heap checker in your program.
|
|
|
|
Due to an implementation detail, you cannot place multiple death test assertions
|
|
on the same line; otherwise, compilation will fail with an unobvious error
|
|
message.
|
|
|
|
Despite the improved thread safety afforded by the "threadsafe" style of death
|
|
test, thread problems such as deadlock are still possible in the presence of
|
|
handlers registered with `pthread_atfork(3)`.
|
|
|
|
## Using Assertions in Sub-routines
|
|
|
|
{: .callout .note}
|
|
Note: If you want to put a series of test assertions in a subroutine to check
|
|
for a complex condition, consider using
|
|
[a custom GMock matcher](gmock_cook_book.md#NewMatchers) instead. This lets you
|
|
provide a more readable error message in case of failure and avoid all of the
|
|
issues described below.
|
|
|
|
### Adding Traces to Assertions
|
|
|
|
If a test sub-routine is called from several places, when an assertion inside it
|
|
fails, it can be hard to tell which invocation of the sub-routine the failure is
|
|
from. You can alleviate this problem using extra logging or custom failure
|
|
messages, but that usually clutters up your tests. A better solution is to use
|
|
the `SCOPED_TRACE` macro or the `ScopedTrace` utility:
|
|
|
|
```c++
|
|
SCOPED_TRACE(message);
|
|
```
|
|
|
|
```c++
|
|
ScopedTrace trace("file_path", line_number, message);
|
|
```
|
|
|
|
where `message` can be anything streamable to `std::ostream`. `SCOPED_TRACE`
|
|
macro will cause the current file name, line number, and the given message to be
|
|
added in every failure message. `ScopedTrace` accepts explicit file name and
|
|
line number in arguments, which is useful for writing test helpers. The effect
|
|
will be undone when the control leaves the current lexical scope.
|
|
|
|
For example,
|
|
|
|
```c++
|
|
10: void Sub1(int n) {
|
|
11: EXPECT_EQ(Bar(n), 1);
|
|
12: EXPECT_EQ(Bar(n + 1), 2);
|
|
13: }
|
|
14:
|
|
15: TEST(FooTest, Bar) {
|
|
16: {
|
|
17: SCOPED_TRACE("A"); // This trace point will be included in
|
|
18: // every failure in this scope.
|
|
19: Sub1(1);
|
|
20: }
|
|
21: // Now it won't.
|
|
22: Sub1(9);
|
|
23: }
|
|
```
|
|
|
|
could result in messages like these:
|
|
|
|
```none
|
|
path/to/foo_test.cc:11: Failure
|
|
Value of: Bar(n)
|
|
Expected: 1
|
|
Actual: 2
|
|
Google Test trace:
|
|
path/to/foo_test.cc:17: A
|
|
|
|
path/to/foo_test.cc:12: Failure
|
|
Value of: Bar(n + 1)
|
|
Expected: 2
|
|
Actual: 3
|
|
```
|
|
|
|
Without the trace, it would've been difficult to know which invocation of
|
|
`Sub1()` the two failures come from respectively. (You could add an extra
|
|
message to each assertion in `Sub1()` to indicate the value of `n`, but that's
|
|
tedious.)
|
|
|
|
Some tips on using `SCOPED_TRACE`:
|
|
|
|
1. With a suitable message, it's often enough to use `SCOPED_TRACE` at the
|
|
beginning of a sub-routine, instead of at each call site.
|
|
2. When calling sub-routines inside a loop, make the loop iterator part of the
|
|
message in `SCOPED_TRACE` such that you can know which iteration the failure
|
|
is from.
|
|
3. Sometimes the line number of the trace point is enough for identifying the
|
|
particular invocation of a sub-routine. In this case, you don't have to
|
|
choose a unique message for `SCOPED_TRACE`. You can simply use `""`.
|
|
4. You can use `SCOPED_TRACE` in an inner scope when there is one in the outer
|
|
scope. In this case, all active trace points will be included in the failure
|
|
messages, in reverse order they are encountered.
|
|
5. The trace dump is clickable in Emacs - hit `return` on a line number and
|
|
you'll be taken to that line in the source file!
|
|
|
|
### Propagating Fatal Failures
|
|
|
|
A common pitfall when using `ASSERT_*` and `FAIL*` is not understanding that
|
|
when they fail they only abort the _current function_, not the entire test. For
|
|
example, the following test will segfault:
|
|
|
|
```c++
|
|
void Subroutine() {
|
|
// Generates a fatal failure and aborts the current function.
|
|
ASSERT_EQ(1, 2);
|
|
|
|
// The following won't be executed.
|
|
...
|
|
}
|
|
|
|
TEST(FooTest, Bar) {
|
|
Subroutine(); // The intended behavior is for the fatal failure
|
|
// in Subroutine() to abort the entire test.
|
|
|
|
// The actual behavior: the function goes on after Subroutine() returns.
|
|
int* p = nullptr;
|
|
*p = 3; // Segfault!
|
|
}
|
|
```
|
|
|
|
To alleviate this, googletest provides three different solutions. You could use
|
|
either exceptions, the `(ASSERT|EXPECT)_NO_FATAL_FAILURE` assertions or the
|
|
`HasFatalFailure()` function. They are described in the following two
|
|
subsections.
|
|
|
|
#### Asserting on Subroutines with an exception
|
|
|
|
The following code can turn ASSERT-failure into an exception:
|
|
|
|
```c++
|
|
class ThrowListener : public testing::EmptyTestEventListener {
|
|
void OnTestPartResult(const testing::TestPartResult& result) override {
|
|
if (result.type() == testing::TestPartResult::kFatalFailure) {
|
|
throw testing::AssertionException(result);
|
|
}
|
|
}
|
|
};
|
|
int main(int argc, char** argv) {
|
|
...
|
|
testing::UnitTest::GetInstance()->listeners().Append(new ThrowListener);
|
|
return RUN_ALL_TESTS();
|
|
}
|
|
```
|
|
|
|
This listener should be added after other listeners if you have any, otherwise
|
|
they won't see failed `OnTestPartResult`.
|
|
|
|
#### Asserting on Subroutines
|
|
|
|
As shown above, if your test calls a subroutine that has an `ASSERT_*` failure
|
|
in it, the test will continue after the subroutine returns. This may not be what
|
|
you want.
|
|
|
|
Often people want fatal failures to propagate like exceptions. For that
|
|
googletest offers the following macros:
|
|
|
|
Fatal assertion | Nonfatal assertion | Verifies
|
|
------------------------------------- | ------------------------------------- | --------
|
|
`ASSERT_NO_FATAL_FAILURE(statement);` | `EXPECT_NO_FATAL_FAILURE(statement);` | `statement` doesn't generate any new fatal failures in the current thread.
|
|
|
|
Only failures in the thread that executes the assertion are checked to determine
|
|
the result of this type of assertions. If `statement` creates new threads,
|
|
failures in these threads are ignored.
|
|
|
|
Examples:
|
|
|
|
```c++
|
|
ASSERT_NO_FATAL_FAILURE(Foo());
|
|
|
|
int i;
|
|
EXPECT_NO_FATAL_FAILURE({
|
|
i = Bar();
|
|
});
|
|
```
|
|
|
|
Assertions from multiple threads are currently not supported on Windows.
|
|
|
|
#### Checking for Failures in the Current Test
|
|
|
|
`HasFatalFailure()` in the `::testing::Test` class returns `true` if an
|
|
assertion in the current test has suffered a fatal failure. This allows
|
|
functions to catch fatal failures in a sub-routine and return early.
|
|
|
|
```c++
|
|
class Test {
|
|
public:
|
|
...
|
|
static bool HasFatalFailure();
|
|
};
|
|
```
|
|
|
|
The typical usage, which basically simulates the behavior of a thrown exception,
|
|
is:
|
|
|
|
```c++
|
|
TEST(FooTest, Bar) {
|
|
Subroutine();
|
|
// Aborts if Subroutine() had a fatal failure.
|
|
if (HasFatalFailure()) return;
|
|
|
|
// The following won't be executed.
|
|
...
|
|
}
|
|
```
|
|
|
|
If `HasFatalFailure()` is used outside of `TEST()` , `TEST_F()` , or a test
|
|
fixture, you must add the `::testing::Test::` prefix, as in:
|
|
|
|
```c++
|
|
if (testing::Test::HasFatalFailure()) return;
|
|
```
|
|
|
|
Similarly, `HasNonfatalFailure()` returns `true` if the current test has at
|
|
least one non-fatal failure, and `HasFailure()` returns `true` if the current
|
|
test has at least one failure of either kind.
|
|
|
|
## Logging Additional Information
|
|
|
|
In your test code, you can call `RecordProperty("key", value)` to log additional
|
|
information, where `value` can be either a string or an `int`. The *last* value
|
|
recorded for a key will be emitted to the
|
|
[XML output](#generating-an-xml-report) if you specify one. For example, the
|
|
test
|
|
|
|
```c++
|
|
TEST_F(WidgetUsageTest, MinAndMaxWidgets) {
|
|
RecordProperty("MaximumWidgets", ComputeMaxUsage());
|
|
RecordProperty("MinimumWidgets", ComputeMinUsage());
|
|
}
|
|
```
|
|
|
|
will output XML like this:
|
|
|
|
```xml
|
|
...
|
|
<testcase name="MinAndMaxWidgets" status="run" time="0.006" classname="WidgetUsageTest" MaximumWidgets="12" MinimumWidgets="9" />
|
|
...
|
|
```
|
|
|
|
{: .callout .note}
|
|
> NOTE:
|
|
>
|
|
> * `RecordProperty()` is a static member of the `Test` class. Therefore it
|
|
> needs to be prefixed with `::testing::Test::` if used outside of the
|
|
> `TEST` body and the test fixture class.
|
|
> * *`key`* must be a valid XML attribute name, and cannot conflict with the
|
|
> ones already used by googletest (`name`, `status`, `time`, `classname`,
|
|
> `type_param`, and `value_param`).
|
|
> * Calling `RecordProperty()` outside of the lifespan of a test is allowed.
|
|
> If it's called outside of a test but between a test suite's
|
|
> `SetUpTestSuite()` and `TearDownTestSuite()` methods, it will be
|
|
> attributed to the XML element for the test suite. If it's called outside
|
|
> of all test suites (e.g. in a test environment), it will be attributed to
|
|
> the top-level XML element.
|
|
|
|
## Sharing Resources Between Tests in the Same Test Suite
|
|
|
|
googletest creates a new test fixture object for each test in order to make
|
|
tests independent and easier to debug. However, sometimes tests use resources
|
|
that are expensive to set up, making the one-copy-per-test model prohibitively
|
|
expensive.
|
|
|
|
If the tests don't change the resource, there's no harm in their sharing a
|
|
single resource copy. So, in addition to per-test set-up/tear-down, googletest
|
|
also supports per-test-suite set-up/tear-down. To use it:
|
|
|
|
1. In your test fixture class (say `FooTest` ), declare as `static` some member
|
|
variables to hold the shared resources.
|
|
2. Outside your test fixture class (typically just below it), define those
|
|
member variables, optionally giving them initial values.
|
|
3. In the same test fixture class, define a `static void SetUpTestSuite()`
|
|
function (remember not to spell it as **`SetupTestSuite`** with a small
|
|
`u`!) to set up the shared resources and a `static void TearDownTestSuite()`
|
|
function to tear them down.
|
|
|
|
That's it! googletest automatically calls `SetUpTestSuite()` before running the
|
|
*first test* in the `FooTest` test suite (i.e. before creating the first
|
|
`FooTest` object), and calls `TearDownTestSuite()` after running the *last test*
|
|
in it (i.e. after deleting the last `FooTest` object). In between, the tests can
|
|
use the shared resources.
|
|
|
|
Remember that the test order is undefined, so your code can't depend on a test
|
|
preceding or following another. Also, the tests must either not modify the state
|
|
of any shared resource, or, if they do modify the state, they must restore the
|
|
state to its original value before passing control to the next test.
|
|
|
|
Note that `SetUpTestSuite()` may be called multiple times for a test fixture
|
|
class that has derived classes, so you should not expect code in the function
|
|
body to be run only once. Also, derived classes still have access to shared
|
|
resources defined as static members, so careful consideration is needed when
|
|
managing shared resources to avoid memory leaks.
|
|
|
|
Here's an example of per-test-suite set-up and tear-down:
|
|
|
|
```c++
|
|
class FooTest : public testing::Test {
|
|
protected:
|
|
// Per-test-suite set-up.
|
|
// Called before the first test in this test suite.
|
|
// Can be omitted if not needed.
|
|
static void SetUpTestSuite() {
|
|
// Avoid reallocating static objects if called in subclasses of FooTest.
|
|
if (shared_resource_ == nullptr) {
|
|
shared_resource_ = new ...;
|
|
}
|
|
}
|
|
|
|
// Per-test-suite tear-down.
|
|
// Called after the last test in this test suite.
|
|
// Can be omitted if not needed.
|
|
static void TearDownTestSuite() {
|
|
delete shared_resource_;
|
|
shared_resource_ = nullptr;
|
|
}
|
|
|
|
// You can define per-test set-up logic as usual.
|
|
void SetUp() override { ... }
|
|
|
|
// You can define per-test tear-down logic as usual.
|
|
void TearDown() override { ... }
|
|
|
|
// Some expensive resource shared by all tests.
|
|
static T* shared_resource_;
|
|
};
|
|
|
|
T* FooTest::shared_resource_ = nullptr;
|
|
|
|
TEST_F(FooTest, Test1) {
|
|
... you can refer to shared_resource_ here ...
|
|
}
|
|
|
|
TEST_F(FooTest, Test2) {
|
|
... you can refer to shared_resource_ here ...
|
|
}
|
|
```
|
|
|
|
{: .callout .note}
|
|
NOTE: Though the above code declares `SetUpTestSuite()` protected, it may
|
|
sometimes be necessary to declare it public, such as when using it with
|
|
`TEST_P`.
|
|
|
|
## Global Set-Up and Tear-Down
|
|
|
|
Just as you can do set-up and tear-down at the test level and the test suite
|
|
level, you can also do it at the test program level. Here's how.
|
|
|
|
First, you subclass the `::testing::Environment` class to define a test
|
|
environment, which knows how to set-up and tear-down:
|
|
|
|
```c++
|
|
class Environment : public ::testing::Environment {
|
|
public:
|
|
~Environment() override {}
|
|
|
|
// Override this to define how to set up the environment.
|
|
void SetUp() override {}
|
|
|
|
// Override this to define how to tear down the environment.
|
|
void TearDown() override {}
|
|
};
|
|
```
|
|
|
|
Then, you register an instance of your environment class with googletest by
|
|
calling the `::testing::AddGlobalTestEnvironment()` function:
|
|
|
|
```c++
|
|
Environment* AddGlobalTestEnvironment(Environment* env);
|
|
```
|
|
|
|
Now, when `RUN_ALL_TESTS()` is called, it first calls the `SetUp()` method of
|
|
each environment object, then runs the tests if none of the environments
|
|
reported fatal failures and `GTEST_SKIP()` was not called. `RUN_ALL_TESTS()`
|
|
always calls `TearDown()` with each environment object, regardless of whether or
|
|
not the tests were run.
|
|
|
|
It's OK to register multiple environment objects. In this suite, their `SetUp()`
|
|
will be called in the order they are registered, and their `TearDown()` will be
|
|
called in the reverse order.
|
|
|
|
Note that googletest takes ownership of the registered environment objects.
|
|
Therefore **do not delete them** by yourself.
|
|
|
|
You should call `AddGlobalTestEnvironment()` before `RUN_ALL_TESTS()` is called,
|
|
probably in `main()`. If you use `gtest_main`, you need to call this before
|
|
`main()` starts for it to take effect. One way to do this is to define a global
|
|
variable like this:
|
|
|
|
```c++
|
|
testing::Environment* const foo_env =
|
|
testing::AddGlobalTestEnvironment(new FooEnvironment);
|
|
```
|
|
|
|
However, we strongly recommend you to write your own `main()` and call
|
|
`AddGlobalTestEnvironment()` there, as relying on initialization of global
|
|
variables makes the code harder to read and may cause problems when you register
|
|
multiple environments from different translation units and the environments have
|
|
dependencies among them (remember that the compiler doesn't guarantee the order
|
|
in which global variables from different translation units are initialized).
|
|
|
|
## Value-Parameterized Tests
|
|
|
|
*Value-parameterized tests* allow you to test your code with different
|
|
parameters without writing multiple copies of the same test. This is useful in a
|
|
number of situations, for example:
|
|
|
|
* You have a piece of code whose behavior is affected by one or more
|
|
command-line flags. You want to make sure your code performs correctly for
|
|
various values of those flags.
|
|
* You want to test different implementations of an OO interface.
|
|
* You want to test your code over various inputs (a.k.a. data-driven testing).
|
|
This feature is easy to abuse, so please exercise your good sense when doing
|
|
it!
|
|
|
|
### How to Write Value-Parameterized Tests
|
|
|
|
To write value-parameterized tests, first you should define a fixture class. It
|
|
must be derived from both `testing::Test` and `testing::WithParamInterface<T>`
|
|
(the latter is a pure interface), where `T` is the type of your parameter
|
|
values. For convenience, you can just derive the fixture class from
|
|
`testing::TestWithParam<T>`, which itself is derived from both `testing::Test`
|
|
and `testing::WithParamInterface<T>`. `T` can be any copyable type. If it's a
|
|
raw pointer, you are responsible for managing the lifespan of the pointed
|
|
values.
|
|
|
|
{: .callout .note}
|
|
NOTE: If your test fixture defines `SetUpTestSuite()` or `TearDownTestSuite()`
|
|
they must be declared **public** rather than **protected** in order to use
|
|
`TEST_P`.
|
|
|
|
```c++
|
|
class FooTest :
|
|
public testing::TestWithParam<const char*> {
|
|
// You can implement all the usual fixture class members here.
|
|
// To access the test parameter, call GetParam() from class
|
|
// TestWithParam<T>.
|
|
};
|
|
|
|
// Or, when you want to add parameters to a pre-existing fixture class:
|
|
class BaseTest : public testing::Test {
|
|
...
|
|
};
|
|
class BarTest : public BaseTest,
|
|
public testing::WithParamInterface<const char*> {
|
|
...
|
|
};
|
|
```
|
|
|
|
Then, use the `TEST_P` macro to define as many test patterns using this fixture
|
|
as you want. The `_P` suffix is for "parameterized" or "pattern", whichever you
|
|
prefer to think.
|
|
|
|
```c++
|
|
TEST_P(FooTest, DoesBlah) {
|
|
// Inside a test, access the test parameter with the GetParam() method
|
|
// of the TestWithParam<T> class:
|
|
EXPECT_TRUE(foo.Blah(GetParam()));
|
|
...
|
|
}
|
|
|
|
TEST_P(FooTest, HasBlahBlah) {
|
|
...
|
|
}
|
|
```
|
|
|
|
Finally, you can use the `INSTANTIATE_TEST_SUITE_P` macro to instantiate the
|
|
test suite with any set of parameters you want. GoogleTest defines a number of
|
|
functions for generating test parameters—see details at
|
|
[`INSTANTIATE_TEST_SUITE_P`](reference/testing.md#INSTANTIATE_TEST_SUITE_P) in
|
|
the Testing Reference.
|
|
|
|
For example, the following statement will instantiate tests from the `FooTest`
|
|
test suite each with parameter values `"meeny"`, `"miny"`, and `"moe"` using the
|
|
[`Values`](reference/testing.md#param-generators) parameter generator:
|
|
|
|
```c++
|
|
INSTANTIATE_TEST_SUITE_P(MeenyMinyMoe,
|
|
FooTest,
|
|
testing::Values("meeny", "miny", "moe"));
|
|
```
|
|
|
|
{: .callout .note}
|
|
NOTE: The code above must be placed at global or namespace scope, not at
|
|
function scope.
|
|
|
|
The first argument to `INSTANTIATE_TEST_SUITE_P` is a unique name for the
|
|
instantiation of the test suite. The next argument is the name of the test
|
|
pattern, and the last is the
|
|
[parameter generator](reference/testing.md#param-generators).
|
|
|
|
You can instantiate a test pattern more than once, so to distinguish different
|
|
instances of the pattern, the instantiation name is added as a prefix to the
|
|
actual test suite name. Remember to pick unique prefixes for different
|
|
instantiations. The tests from the instantiation above will have these names:
|
|
|
|
* `MeenyMinyMoe/FooTest.DoesBlah/0` for `"meeny"`
|
|
* `MeenyMinyMoe/FooTest.DoesBlah/1` for `"miny"`
|
|
* `MeenyMinyMoe/FooTest.DoesBlah/2` for `"moe"`
|
|
* `MeenyMinyMoe/FooTest.HasBlahBlah/0` for `"meeny"`
|
|
* `MeenyMinyMoe/FooTest.HasBlahBlah/1` for `"miny"`
|
|
* `MeenyMinyMoe/FooTest.HasBlahBlah/2` for `"moe"`
|
|
|
|
You can use these names in [`--gtest_filter`](#running-a-subset-of-the-tests).
|
|
|
|
The following statement will instantiate all tests from `FooTest` again, each
|
|
with parameter values `"cat"` and `"dog"` using the
|
|
[`ValuesIn`](reference/testing.md#param-generators) parameter generator:
|
|
|
|
```c++
|
|
const char* pets[] = {"cat", "dog"};
|
|
INSTANTIATE_TEST_SUITE_P(Pets, FooTest, testing::ValuesIn(pets));
|
|
```
|
|
|
|
The tests from the instantiation above will have these names:
|
|
|
|
* `Pets/FooTest.DoesBlah/0` for `"cat"`
|
|
* `Pets/FooTest.DoesBlah/1` for `"dog"`
|
|
* `Pets/FooTest.HasBlahBlah/0` for `"cat"`
|
|
* `Pets/FooTest.HasBlahBlah/1` for `"dog"`
|
|
|
|
Please note that `INSTANTIATE_TEST_SUITE_P` will instantiate *all* tests in the
|
|
given test suite, whether their definitions come before or *after* the
|
|
`INSTANTIATE_TEST_SUITE_P` statement.
|
|
|
|
Additionally, by default, every `TEST_P` without a corresponding
|
|
`INSTANTIATE_TEST_SUITE_P` causes a failing test in test suite
|
|
`GoogleTestVerification`. If you have a test suite where that omission is not an
|
|
error, for example it is in a library that may be linked in for other reasons or
|
|
where the list of test cases is dynamic and may be empty, then this check can be
|
|
suppressed by tagging the test suite:
|
|
|
|
```c++
|
|
GTEST_ALLOW_UNINSTANTIATED_PARAMETERIZED_TEST(FooTest);
|
|
```
|
|
|
|
You can see [sample7_unittest.cc] and [sample8_unittest.cc] for more examples.
|
|
|
|
[sample7_unittest.cc]: https://github.com/google/googletest/blob/master/googletest/samples/sample7_unittest.cc "Parameterized Test example"
|
|
[sample8_unittest.cc]: https://github.com/google/googletest/blob/master/googletest/samples/sample8_unittest.cc "Parameterized Test example with multiple parameters"
|
|
|
|
### Creating Value-Parameterized Abstract Tests
|
|
|
|
In the above, we define and instantiate `FooTest` in the *same* source file.
|
|
Sometimes you may want to define value-parameterized tests in a library and let
|
|
other people instantiate them later. This pattern is known as *abstract tests*.
|
|
As an example of its application, when you are designing an interface you can
|
|
write a standard suite of abstract tests (perhaps using a factory function as
|
|
the test parameter) that all implementations of the interface are expected to
|
|
pass. When someone implements the interface, they can instantiate your suite to
|
|
get all the interface-conformance tests for free.
|
|
|
|
To define abstract tests, you should organize your code like this:
|
|
|
|
1. Put the definition of the parameterized test fixture class (e.g. `FooTest`)
|
|
in a header file, say `foo_param_test.h`. Think of this as *declaring* your
|
|
abstract tests.
|
|
2. Put the `TEST_P` definitions in `foo_param_test.cc`, which includes
|
|
`foo_param_test.h`. Think of this as *implementing* your abstract tests.
|
|
|
|
Once they are defined, you can instantiate them by including `foo_param_test.h`,
|
|
invoking `INSTANTIATE_TEST_SUITE_P()`, and depending on the library target that
|
|
contains `foo_param_test.cc`. You can instantiate the same abstract test suite
|
|
multiple times, possibly in different source files.
|
|
|
|
### Specifying Names for Value-Parameterized Test Parameters
|
|
|
|
The optional last argument to `INSTANTIATE_TEST_SUITE_P()` allows the user to
|
|
specify a function or functor that generates custom test name suffixes based on
|
|
the test parameters. The function should accept one argument of type
|
|
`testing::TestParamInfo<class ParamType>`, and return `std::string`.
|
|
|
|
`testing::PrintToStringParamName` is a builtin test suffix generator that
|
|
returns the value of `testing::PrintToString(GetParam())`. It does not work for
|
|
`std::string` or C strings.
|
|
|
|
{: .callout .note}
|
|
NOTE: test names must be non-empty, unique, and may only contain ASCII
|
|
alphanumeric characters. In particular, they
|
|
[should not contain underscores](faq.md#why-should-test-suite-names-and-test-names-not-contain-underscore)
|
|
|
|
```c++
|
|
class MyTestSuite : public testing::TestWithParam<int> {};
|
|
|
|
TEST_P(MyTestSuite, MyTest)
|
|
{
|
|
std::cout << "Example Test Param: " << GetParam() << std::endl;
|
|
}
|
|
|
|
INSTANTIATE_TEST_SUITE_P(MyGroup, MyTestSuite, testing::Range(0, 10),
|
|
testing::PrintToStringParamName());
|
|
```
|
|
|
|
Providing a custom functor allows for more control over test parameter name
|
|
generation, especially for types where the automatic conversion does not
|
|
generate helpful parameter names (e.g. strings as demonstrated above). The
|
|
following example illustrates this for multiple parameters, an enumeration type
|
|
and a string, and also demonstrates how to combine generators. It uses a lambda
|
|
for conciseness:
|
|
|
|
```c++
|
|
enum class MyType { MY_FOO = 0, MY_BAR = 1 };
|
|
|
|
class MyTestSuite : public testing::TestWithParam<std::tuple<MyType, std::string>> {
|
|
};
|
|
|
|
INSTANTIATE_TEST_SUITE_P(
|
|
MyGroup, MyTestSuite,
|
|
testing::Combine(
|
|
testing::Values(MyType::MY_FOO, MyType::MY_BAR),
|
|
testing::Values("A", "B")),
|
|
[](const testing::TestParamInfo<MyTestSuite::ParamType>& info) {
|
|
std::string name = absl::StrCat(
|
|
std::get<0>(info.param) == MyType::MY_FOO ? "Foo" : "Bar",
|
|
std::get<1>(info.param));
|
|
absl::c_replace_if(name, [](char c) { return !std::isalnum(c); }, '_');
|
|
return name;
|
|
});
|
|
```
|
|
|
|
## Typed Tests
|
|
|
|
Suppose you have multiple implementations of the same interface and want to make
|
|
sure that all of them satisfy some common requirements. Or, you may have defined
|
|
several types that are supposed to conform to the same "concept" and you want to
|
|
verify it. In both cases, you want the same test logic repeated for different
|
|
types.
|
|
|
|
While you can write one `TEST` or `TEST_F` for each type you want to test (and
|
|
you may even factor the test logic into a function template that you invoke from
|
|
the `TEST`), it's tedious and doesn't scale: if you want `m` tests over `n`
|
|
types, you'll end up writing `m*n` `TEST`s.
|
|
|
|
*Typed tests* allow you to repeat the same test logic over a list of types. You
|
|
only need to write the test logic once, although you must know the type list
|
|
when writing typed tests. Here's how you do it:
|
|
|
|
First, define a fixture class template. It should be parameterized by a type.
|
|
Remember to derive it from `::testing::Test`:
|
|
|
|
```c++
|
|
template <typename T>
|
|
class FooTest : public testing::Test {
|
|
public:
|
|
...
|
|
using List = std::list<T>;
|
|
static T shared_;
|
|
T value_;
|
|
};
|
|
```
|
|
|
|
Next, associate a list of types with the test suite, which will be repeated for
|
|
each type in the list:
|
|
|
|
```c++
|
|
using MyTypes = ::testing::Types<char, int, unsigned int>;
|
|
TYPED_TEST_SUITE(FooTest, MyTypes);
|
|
```
|
|
|
|
The type alias (`using` or `typedef`) is necessary for the `TYPED_TEST_SUITE`
|
|
macro to parse correctly. Otherwise the compiler will think that each comma in
|
|
the type list introduces a new macro argument.
|
|
|
|
Then, use `TYPED_TEST()` instead of `TEST_F()` to define a typed test for this
|
|
test suite. You can repeat this as many times as you want:
|
|
|
|
```c++
|
|
TYPED_TEST(FooTest, DoesBlah) {
|
|
// Inside a test, refer to the special name TypeParam to get the type
|
|
// parameter. Since we are inside a derived class template, C++ requires
|
|
// us to visit the members of FooTest via 'this'.
|
|
TypeParam n = this->value_;
|
|
|
|
// To visit static members of the fixture, add the 'TestFixture::'
|
|
// prefix.
|
|
n += TestFixture::shared_;
|
|
|
|
// To refer to typedefs in the fixture, add the 'typename TestFixture::'
|
|
// prefix. The 'typename' is required to satisfy the compiler.
|
|
typename TestFixture::List values;
|
|
|
|
values.push_back(n);
|
|
...
|
|
}
|
|
|
|
TYPED_TEST(FooTest, HasPropertyA) { ... }
|
|
```
|
|
|
|
You can see [sample6_unittest.cc] for a complete example.
|
|
|
|
[sample6_unittest.cc]: https://github.com/google/googletest/blob/master/googletest/samples/sample6_unittest.cc "Typed Test example"
|
|
|
|
## Type-Parameterized Tests
|
|
|
|
*Type-parameterized tests* are like typed tests, except that they don't require
|
|
you to know the list of types ahead of time. Instead, you can define the test
|
|
logic first and instantiate it with different type lists later. You can even
|
|
instantiate it more than once in the same program.
|
|
|
|
If you are designing an interface or concept, you can define a suite of
|
|
type-parameterized tests to verify properties that any valid implementation of
|
|
the interface/concept should have. Then, the author of each implementation can
|
|
just instantiate the test suite with their type to verify that it conforms to
|
|
the requirements, without having to write similar tests repeatedly. Here's an
|
|
example:
|
|
|
|
First, define a fixture class template, as we did with typed tests:
|
|
|
|
```c++
|
|
template <typename T>
|
|
class FooTest : public testing::Test {
|
|
...
|
|
};
|
|
```
|
|
|
|
Next, declare that you will define a type-parameterized test suite:
|
|
|
|
```c++
|
|
TYPED_TEST_SUITE_P(FooTest);
|
|
```
|
|
|
|
Then, use `TYPED_TEST_P()` to define a type-parameterized test. You can repeat
|
|
this as many times as you want:
|
|
|
|
```c++
|
|
TYPED_TEST_P(FooTest, DoesBlah) {
|
|
// Inside a test, refer to TypeParam to get the type parameter.
|
|
TypeParam n = 0;
|
|
...
|
|
}
|
|
|
|
TYPED_TEST_P(FooTest, HasPropertyA) { ... }
|
|
```
|
|
|
|
Now the tricky part: you need to register all test patterns using the
|
|
`REGISTER_TYPED_TEST_SUITE_P` macro before you can instantiate them. The first
|
|
argument of the macro is the test suite name; the rest are the names of the
|
|
tests in this test suite:
|
|
|
|
```c++
|
|
REGISTER_TYPED_TEST_SUITE_P(FooTest,
|
|
DoesBlah, HasPropertyA);
|
|
```
|
|
|
|
Finally, you are free to instantiate the pattern with the types you want. If you
|
|
put the above code in a header file, you can `#include` it in multiple C++
|
|
source files and instantiate it multiple times.
|
|
|
|
```c++
|
|
using MyTypes = ::testing::Types<char, int, unsigned int>;
|
|
INSTANTIATE_TYPED_TEST_SUITE_P(My, FooTest, MyTypes);
|
|
```
|
|
|
|
To distinguish different instances of the pattern, the first argument to the
|
|
`INSTANTIATE_TYPED_TEST_SUITE_P` macro is a prefix that will be added to the
|
|
actual test suite name. Remember to pick unique prefixes for different
|
|
instances.
|
|
|
|
In the special case where the type list contains only one type, you can write
|
|
that type directly without `::testing::Types<...>`, like this:
|
|
|
|
```c++
|
|
INSTANTIATE_TYPED_TEST_SUITE_P(My, FooTest, int);
|
|
```
|
|
|
|
You can see [sample6_unittest.cc] for a complete example.
|
|
|
|
## Testing Private Code
|
|
|
|
If you change your software's internal implementation, your tests should not
|
|
break as long as the change is not observable by users. Therefore, **per the
|
|
black-box testing principle, most of the time you should test your code through
|
|
its public interfaces.**
|
|
|
|
**If you still find yourself needing to test internal implementation code,
|
|
consider if there's a better design.** The desire to test internal
|
|
implementation is often a sign that the class is doing too much. Consider
|
|
extracting an implementation class, and testing it. Then use that implementation
|
|
class in the original class.
|
|
|
|
If you absolutely have to test non-public interface code though, you can. There
|
|
are two cases to consider:
|
|
|
|
* Static functions ( *not* the same as static member functions!) or unnamed
|
|
namespaces, and
|
|
* Private or protected class members
|
|
|
|
To test them, we use the following special techniques:
|
|
|
|
* Both static functions and definitions/declarations in an unnamed namespace
|
|
are only visible within the same translation unit. To test them, you can
|
|
`#include` the entire `.cc` file being tested in your `*_test.cc` file.
|
|
(#including `.cc` files is not a good way to reuse code - you should not do
|
|
this in production code!)
|
|
|
|
However, a better approach is to move the private code into the
|
|
`foo::internal` namespace, where `foo` is the namespace your project
|
|
normally uses, and put the private declarations in a `*-internal.h` file.
|
|
Your production `.cc` files and your tests are allowed to include this
|
|
internal header, but your clients are not. This way, you can fully test your
|
|
internal implementation without leaking it to your clients.
|
|
|
|
* Private class members are only accessible from within the class or by
|
|
friends. To access a class' private members, you can declare your test
|
|
fixture as a friend to the class and define accessors in your fixture. Tests
|
|
using the fixture can then access the private members of your production
|
|
class via the accessors in the fixture. Note that even though your fixture
|
|
is a friend to your production class, your tests are not automatically
|
|
friends to it, as they are technically defined in sub-classes of the
|
|
fixture.
|
|
|
|
Another way to test private members is to refactor them into an
|
|
implementation class, which is then declared in a `*-internal.h` file. Your
|
|
clients aren't allowed to include this header but your tests can. Such is
|
|
called the
|
|
[Pimpl](https://www.gamedev.net/articles/programming/general-and-gameplay-programming/the-c-pimpl-r1794/)
|
|
(Private Implementation) idiom.
|
|
|
|
Or, you can declare an individual test as a friend of your class by adding
|
|
this line in the class body:
|
|
|
|
```c++
|
|
FRIEND_TEST(TestSuiteName, TestName);
|
|
```
|
|
|
|
For example,
|
|
|
|
```c++
|
|
// foo.h
|
|
class Foo {
|
|
...
|
|
private:
|
|
FRIEND_TEST(FooTest, BarReturnsZeroOnNull);
|
|
|
|
int Bar(void* x);
|
|
};
|
|
|
|
// foo_test.cc
|
|
...
|
|
TEST(FooTest, BarReturnsZeroOnNull) {
|
|
Foo foo;
|
|
EXPECT_EQ(foo.Bar(NULL), 0); // Uses Foo's private member Bar().
|
|
}
|
|
```
|
|
|
|
Pay special attention when your class is defined in a namespace. If you want
|
|
your test fixtures and tests to be friends of your class, then they must be
|
|
defined in the exact same namespace (no anonymous or inline namespaces).
|
|
|
|
For example, if the code to be tested looks like:
|
|
|
|
```c++
|
|
namespace my_namespace {
|
|
|
|
class Foo {
|
|
friend class FooTest;
|
|
FRIEND_TEST(FooTest, Bar);
|
|
FRIEND_TEST(FooTest, Baz);
|
|
... definition of the class Foo ...
|
|
};
|
|
|
|
} // namespace my_namespace
|
|
```
|
|
|
|
Your test code should be something like:
|
|
|
|
```c++
|
|
namespace my_namespace {
|
|
|
|
class FooTest : public testing::Test {
|
|
protected:
|
|
...
|
|
};
|
|
|
|
TEST_F(FooTest, Bar) { ... }
|
|
TEST_F(FooTest, Baz) { ... }
|
|
|
|
} // namespace my_namespace
|
|
```
|
|
|
|
## "Catching" Failures
|
|
|
|
If you are building a testing utility on top of googletest, you'll want to test
|
|
your utility. What framework would you use to test it? googletest, of course.
|
|
|
|
The challenge is to verify that your testing utility reports failures correctly.
|
|
In frameworks that report a failure by throwing an exception, you could catch
|
|
the exception and assert on it. But googletest doesn't use exceptions, so how do
|
|
we test that a piece of code generates an expected failure?
|
|
|
|
`"gtest/gtest-spi.h"` contains some constructs to do this.
|
|
After #including this header, you can use
|
|
|
|
```c++
|
|
EXPECT_FATAL_FAILURE(statement, substring);
|
|
```
|
|
|
|
to assert that `statement` generates a fatal (e.g. `ASSERT_*`) failure in the
|
|
current thread whose message contains the given `substring`, or use
|
|
|
|
```c++
|
|
EXPECT_NONFATAL_FAILURE(statement, substring);
|
|
```
|
|
|
|
if you are expecting a non-fatal (e.g. `EXPECT_*`) failure.
|
|
|
|
Only failures in the current thread are checked to determine the result of this
|
|
type of expectations. If `statement` creates new threads, failures in these
|
|
threads are also ignored. If you want to catch failures in other threads as
|
|
well, use one of the following macros instead:
|
|
|
|
```c++
|
|
EXPECT_FATAL_FAILURE_ON_ALL_THREADS(statement, substring);
|
|
EXPECT_NONFATAL_FAILURE_ON_ALL_THREADS(statement, substring);
|
|
```
|
|
|
|
{: .callout .note}
|
|
NOTE: Assertions from multiple threads are currently not supported on Windows.
|
|
|
|
For technical reasons, there are some caveats:
|
|
|
|
1. You cannot stream a failure message to either macro.
|
|
|
|
2. `statement` in `EXPECT_FATAL_FAILURE{_ON_ALL_THREADS}()` cannot reference
|
|
local non-static variables or non-static members of `this` object.
|
|
|
|
3. `statement` in `EXPECT_FATAL_FAILURE{_ON_ALL_THREADS}()` cannot return a
|
|
value.
|
|
|
|
## Registering tests programmatically
|
|
|
|
The `TEST` macros handle the vast majority of all use cases, but there are few
|
|
where runtime registration logic is required. For those cases, the framework
|
|
provides the `::testing::RegisterTest` that allows callers to register arbitrary
|
|
tests dynamically.
|
|
|
|
This is an advanced API only to be used when the `TEST` macros are insufficient.
|
|
The macros should be preferred when possible, as they avoid most of the
|
|
complexity of calling this function.
|
|
|
|
It provides the following signature:
|
|
|
|
```c++
|
|
template <typename Factory>
|
|
TestInfo* RegisterTest(const char* test_suite_name, const char* test_name,
|
|
const char* type_param, const char* value_param,
|
|
const char* file, int line, Factory factory);
|
|
```
|
|
|
|
The `factory` argument is a factory callable (move-constructible) object or
|
|
function pointer that creates a new instance of the Test object. It handles
|
|
ownership to the caller. The signature of the callable is `Fixture*()`, where
|
|
`Fixture` is the test fixture class for the test. All tests registered with the
|
|
same `test_suite_name` must return the same fixture type. This is checked at
|
|
runtime.
|
|
|
|
The framework will infer the fixture class from the factory and will call the
|
|
`SetUpTestSuite` and `TearDownTestSuite` for it.
|
|
|
|
Must be called before `RUN_ALL_TESTS()` is invoked, otherwise behavior is
|
|
undefined.
|
|
|
|
Use case example:
|
|
|
|
```c++
|
|
class MyFixture : public testing::Test {
|
|
public:
|
|
// All of these optional, just like in regular macro usage.
|
|
static void SetUpTestSuite() { ... }
|
|
static void TearDownTestSuite() { ... }
|
|
void SetUp() override { ... }
|
|
void TearDown() override { ... }
|
|
};
|
|
|
|
class MyTest : public MyFixture {
|
|
public:
|
|
explicit MyTest(int data) : data_(data) {}
|
|
void TestBody() override { ... }
|
|
|
|
private:
|
|
int data_;
|
|
};
|
|
|
|
void RegisterMyTests(const std::vector<int>& values) {
|
|
for (int v : values) {
|
|
testing::RegisterTest(
|
|
"MyFixture", ("Test" + std::to_string(v)).c_str(), nullptr,
|
|
std::to_string(v).c_str(),
|
|
__FILE__, __LINE__,
|
|
// Important to use the fixture type as the return type here.
|
|
[=]() -> MyFixture* { return new MyTest(v); });
|
|
}
|
|
}
|
|
...
|
|
int main(int argc, char** argv) {
|
|
testing::InitGoogleTest(&argc, argv);
|
|
std::vector<int> values_to_test = LoadValuesFromConfig();
|
|
RegisterMyTests(values_to_test);
|
|
...
|
|
return RUN_ALL_TESTS();
|
|
}
|
|
```
|
|
|
|
## Getting the Current Test's Name
|
|
|
|
Sometimes a function may need to know the name of the currently running test.
|
|
For example, you may be using the `SetUp()` method of your test fixture to set
|
|
the golden file name based on which test is running. The
|
|
[`TestInfo`](reference/testing.md#TestInfo) class has this information.
|
|
|
|
To obtain a `TestInfo` object for the currently running test, call
|
|
`current_test_info()` on the [`UnitTest`](reference/testing.md#UnitTest)
|
|
singleton object:
|
|
|
|
```c++
|
|
// Gets information about the currently running test.
|
|
// Do NOT delete the returned object - it's managed by the UnitTest class.
|
|
const testing::TestInfo* const test_info =
|
|
testing::UnitTest::GetInstance()->current_test_info();
|
|
|
|
printf("We are in test %s of test suite %s.\n",
|
|
test_info->name(),
|
|
test_info->test_suite_name());
|
|
```
|
|
|
|
`current_test_info()` returns a null pointer if no test is running. In
|
|
particular, you cannot find the test suite name in `SetUpTestSuite()`,
|
|
`TearDownTestSuite()` (where you know the test suite name implicitly), or
|
|
functions called from them.
|
|
|
|
## Extending googletest by Handling Test Events
|
|
|
|
googletest provides an **event listener API** to let you receive notifications
|
|
about the progress of a test program and test failures. The events you can
|
|
listen to include the start and end of the test program, a test suite, or a test
|
|
method, among others. You may use this API to augment or replace the standard
|
|
console output, replace the XML output, or provide a completely different form
|
|
of output, such as a GUI or a database. You can also use test events as
|
|
checkpoints to implement a resource leak checker, for example.
|
|
|
|
### Defining Event Listeners
|
|
|
|
To define a event listener, you subclass either
|
|
[`testing::TestEventListener`](reference/testing.md#TestEventListener) or
|
|
[`testing::EmptyTestEventListener`](reference/testing.md#EmptyTestEventListener)
|
|
The former is an (abstract) interface, where *each pure virtual method can be
|
|
overridden to handle a test event* (For example, when a test starts, the
|
|
`OnTestStart()` method will be called.). The latter provides an empty
|
|
implementation of all methods in the interface, such that a subclass only needs
|
|
to override the methods it cares about.
|
|
|
|
When an event is fired, its context is passed to the handler function as an
|
|
argument. The following argument types are used:
|
|
|
|
* UnitTest reflects the state of the entire test program,
|
|
* TestSuite has information about a test suite, which can contain one or more
|
|
tests,
|
|
* TestInfo contains the state of a test, and
|
|
* TestPartResult represents the result of a test assertion.
|
|
|
|
An event handler function can examine the argument it receives to find out
|
|
interesting information about the event and the test program's state.
|
|
|
|
Here's an example:
|
|
|
|
```c++
|
|
class MinimalistPrinter : public testing::EmptyTestEventListener {
|
|
// Called before a test starts.
|
|
void OnTestStart(const testing::TestInfo& test_info) override {
|
|
printf("*** Test %s.%s starting.\n",
|
|
test_info.test_suite_name(), test_info.name());
|
|
}
|
|
|
|
// Called after a failed assertion or a SUCCESS().
|
|
void OnTestPartResult(const testing::TestPartResult& test_part_result) override {
|
|
printf("%s in %s:%d\n%s\n",
|
|
test_part_result.failed() ? "*** Failure" : "Success",
|
|
test_part_result.file_name(),
|
|
test_part_result.line_number(),
|
|
test_part_result.summary());
|
|
}
|
|
|
|
// Called after a test ends.
|
|
void OnTestEnd(const testing::TestInfo& test_info) override {
|
|
printf("*** Test %s.%s ending.\n",
|
|
test_info.test_suite_name(), test_info.name());
|
|
}
|
|
};
|
|
```
|
|
|
|
### Using Event Listeners
|
|
|
|
To use the event listener you have defined, add an instance of it to the
|
|
googletest event listener list (represented by class
|
|
[`TestEventListeners`](reference/testing.md#TestEventListeners) - note the "s"
|
|
at the end of the name) in your `main()` function, before calling
|
|
`RUN_ALL_TESTS()`:
|
|
|
|
```c++
|
|
int main(int argc, char** argv) {
|
|
testing::InitGoogleTest(&argc, argv);
|
|
// Gets hold of the event listener list.
|
|
testing::TestEventListeners& listeners =
|
|
testing::UnitTest::GetInstance()->listeners();
|
|
// Adds a listener to the end. googletest takes the ownership.
|
|
listeners.Append(new MinimalistPrinter);
|
|
return RUN_ALL_TESTS();
|
|
}
|
|
```
|
|
|
|
There's only one problem: the default test result printer is still in effect, so
|
|
its output will mingle with the output from your minimalist printer. To suppress
|
|
the default printer, just release it from the event listener list and delete it.
|
|
You can do so by adding one line:
|
|
|
|
```c++
|
|
...
|
|
delete listeners.Release(listeners.default_result_printer());
|
|
listeners.Append(new MinimalistPrinter);
|
|
return RUN_ALL_TESTS();
|
|
```
|
|
|
|
Now, sit back and enjoy a completely different output from your tests. For more
|
|
details, see [sample9_unittest.cc].
|
|
|
|
[sample9_unittest.cc]: https://github.com/google/googletest/blob/master/googletest/samples/sample9_unittest.cc "Event listener example"
|
|
|
|
You may append more than one listener to the list. When an `On*Start()` or
|
|
`OnTestPartResult()` event is fired, the listeners will receive it in the order
|
|
they appear in the list (since new listeners are added to the end of the list,
|
|
the default text printer and the default XML generator will receive the event
|
|
first). An `On*End()` event will be received by the listeners in the *reverse*
|
|
order. This allows output by listeners added later to be framed by output from
|
|
listeners added earlier.
|
|
|
|
### Generating Failures in Listeners
|
|
|
|
You may use failure-raising macros (`EXPECT_*()`, `ASSERT_*()`, `FAIL()`, etc)
|
|
when processing an event. There are some restrictions:
|
|
|
|
1. You cannot generate any failure in `OnTestPartResult()` (otherwise it will
|
|
cause `OnTestPartResult()` to be called recursively).
|
|
2. A listener that handles `OnTestPartResult()` is not allowed to generate any
|
|
failure.
|
|
|
|
When you add listeners to the listener list, you should put listeners that
|
|
handle `OnTestPartResult()` *before* listeners that can generate failures. This
|
|
ensures that failures generated by the latter are attributed to the right test
|
|
by the former.
|
|
|
|
See [sample10_unittest.cc] for an example of a failure-raising listener.
|
|
|
|
[sample10_unittest.cc]: https://github.com/google/googletest/blob/master/googletest/samples/sample10_unittest.cc "Failure-raising listener example"
|
|
|
|
## Running Test Programs: Advanced Options
|
|
|
|
googletest test programs are ordinary executables. Once built, you can run them
|
|
directly and affect their behavior via the following environment variables
|
|
and/or command line flags. For the flags to work, your programs must call
|
|
`::testing::InitGoogleTest()` before calling `RUN_ALL_TESTS()`.
|
|
|
|
To see a list of supported flags and their usage, please run your test program
|
|
with the `--help` flag. You can also use `-h`, `-?`, or `/?` for short.
|
|
|
|
If an option is specified both by an environment variable and by a flag, the
|
|
latter takes precedence.
|
|
|
|
### Selecting Tests
|
|
|
|
#### Listing Test Names
|
|
|
|
Sometimes it is necessary to list the available tests in a program before
|
|
running them so that a filter may be applied if needed. Including the flag
|
|
`--gtest_list_tests` overrides all other flags and lists tests in the following
|
|
format:
|
|
|
|
```none
|
|
TestSuite1.
|
|
TestName1
|
|
TestName2
|
|
TestSuite2.
|
|
TestName
|
|
```
|
|
|
|
None of the tests listed are actually run if the flag is provided. There is no
|
|
corresponding environment variable for this flag.
|
|
|
|
#### Running a Subset of the Tests
|
|
|
|
By default, a googletest program runs all tests the user has defined. Sometimes,
|
|
you want to run only a subset of the tests (e.g. for debugging or quickly
|
|
verifying a change). If you set the `GTEST_FILTER` environment variable or the
|
|
`--gtest_filter` flag to a filter string, googletest will only run the tests
|
|
whose full names (in the form of `TestSuiteName.TestName`) match the filter.
|
|
|
|
The format of a filter is a '`:`'-separated list of wildcard patterns (called
|
|
the *positive patterns*) optionally followed by a '`-`' and another
|
|
'`:`'-separated pattern list (called the *negative patterns*). A test matches
|
|
the filter if and only if it matches any of the positive patterns but does not
|
|
match any of the negative patterns.
|
|
|
|
A pattern may contain `'*'` (matches any string) or `'?'` (matches any single
|
|
character). For convenience, the filter `'*-NegativePatterns'` can be also
|
|
written as `'-NegativePatterns'`.
|
|
|
|
For example:
|
|
|
|
* `./foo_test` Has no flag, and thus runs all its tests.
|
|
* `./foo_test --gtest_filter=*` Also runs everything, due to the single
|
|
match-everything `*` value.
|
|
* `./foo_test --gtest_filter=FooTest.*` Runs everything in test suite
|
|
`FooTest` .
|
|
* `./foo_test --gtest_filter=*Null*:*Constructor*` Runs any test whose full
|
|
name contains either `"Null"` or `"Constructor"` .
|
|
* `./foo_test --gtest_filter=-*DeathTest.*` Runs all non-death tests.
|
|
* `./foo_test --gtest_filter=FooTest.*-FooTest.Bar` Runs everything in test
|
|
suite `FooTest` except `FooTest.Bar`.
|
|
* `./foo_test --gtest_filter=FooTest.*:BarTest.*-FooTest.Bar:BarTest.Foo` Runs
|
|
everything in test suite `FooTest` except `FooTest.Bar` and everything in
|
|
test suite `BarTest` except `BarTest.Foo`.
|
|
|
|
#### Stop test execution upon first failure
|
|
|
|
By default, a googletest program runs all tests the user has defined. In some
|
|
cases (e.g. iterative test development & execution) it may be desirable stop
|
|
test execution upon first failure (trading improved latency for completeness).
|
|
If `GTEST_FAIL_FAST` environment variable or `--gtest_fail_fast` flag is set,
|
|
the test runner will stop execution as soon as the first test failure is found.
|
|
|
|
#### Temporarily Disabling Tests
|
|
|
|
If you have a broken test that you cannot fix right away, you can add the
|
|
`DISABLED_` prefix to its name. This will exclude it from execution. This is
|
|
better than commenting out the code or using `#if 0`, as disabled tests are
|
|
still compiled (and thus won't rot).
|
|
|
|
If you need to disable all tests in a test suite, you can either add `DISABLED_`
|
|
to the front of the name of each test, or alternatively add it to the front of
|
|
the test suite name.
|
|
|
|
For example, the following tests won't be run by googletest, even though they
|
|
will still be compiled:
|
|
|
|
```c++
|
|
// Tests that Foo does Abc.
|
|
TEST(FooTest, DISABLED_DoesAbc) { ... }
|
|
|
|
class DISABLED_BarTest : public testing::Test { ... };
|
|
|
|
// Tests that Bar does Xyz.
|
|
TEST_F(DISABLED_BarTest, DoesXyz) { ... }
|
|
```
|
|
|
|
{: .callout .note}
|
|
NOTE: This feature should only be used for temporary pain-relief. You still have
|
|
to fix the disabled tests at a later date. As a reminder, googletest will print
|
|
a banner warning you if a test program contains any disabled tests.
|
|
|
|
{: .callout .tip}
|
|
TIP: You can easily count the number of disabled tests you have using
|
|
`grep`. This number can be used as a metric for
|
|
improving your test quality.
|
|
|
|
#### Temporarily Enabling Disabled Tests
|
|
|
|
To include disabled tests in test execution, just invoke the test program with
|
|
the `--gtest_also_run_disabled_tests` flag or set the
|
|
`GTEST_ALSO_RUN_DISABLED_TESTS` environment variable to a value other than `0`.
|
|
You can combine this with the `--gtest_filter` flag to further select which
|
|
disabled tests to run.
|
|
|
|
### Repeating the Tests
|
|
|
|
Once in a while you'll run into a test whose result is hit-or-miss. Perhaps it
|
|
will fail only 1% of the time, making it rather hard to reproduce the bug under
|
|
a debugger. This can be a major source of frustration.
|
|
|
|
The `--gtest_repeat` flag allows you to repeat all (or selected) test methods in
|
|
a program many times. Hopefully, a flaky test will eventually fail and give you
|
|
a chance to debug. Here's how to use it:
|
|
|
|
```none
|
|
$ foo_test --gtest_repeat=1000
|
|
Repeat foo_test 1000 times and don't stop at failures.
|
|
|
|
$ foo_test --gtest_repeat=-1
|
|
A negative count means repeating forever.
|
|
|
|
$ foo_test --gtest_repeat=1000 --gtest_break_on_failure
|
|
Repeat foo_test 1000 times, stopping at the first failure. This
|
|
is especially useful when running under a debugger: when the test
|
|
fails, it will drop into the debugger and you can then inspect
|
|
variables and stacks.
|
|
|
|
$ foo_test --gtest_repeat=1000 --gtest_filter=FooBar.*
|
|
Repeat the tests whose name matches the filter 1000 times.
|
|
```
|
|
|
|
If your test program contains
|
|
[global set-up/tear-down](#global-set-up-and-tear-down) code, it will be
|
|
repeated in each iteration as well, as the flakiness may be in it. You can also
|
|
specify the repeat count by setting the `GTEST_REPEAT` environment variable.
|
|
|
|
### Shuffling the Tests
|
|
|
|
You can specify the `--gtest_shuffle` flag (or set the `GTEST_SHUFFLE`
|
|
environment variable to `1`) to run the tests in a program in a random order.
|
|
This helps to reveal bad dependencies between tests.
|
|
|
|
By default, googletest uses a random seed calculated from the current time.
|
|
Therefore you'll get a different order every time. The console output includes
|
|
the random seed value, such that you can reproduce an order-related test failure
|
|
later. To specify the random seed explicitly, use the `--gtest_random_seed=SEED`
|
|
flag (or set the `GTEST_RANDOM_SEED` environment variable), where `SEED` is an
|
|
integer in the range [0, 99999]. The seed value 0 is special: it tells
|
|
googletest to do the default behavior of calculating the seed from the current
|
|
time.
|
|
|
|
If you combine this with `--gtest_repeat=N`, googletest will pick a different
|
|
random seed and re-shuffle the tests in each iteration.
|
|
|
|
### Distributing Test Functions to Multiple Machines
|
|
|
|
If you have more than one machine you can use to run a test program, you might
|
|
want to run the test functions in parallel and get the result faster. We call
|
|
this technique *sharding*, where each machine is called a *shard*.
|
|
|
|
GoogleTest is compatible with test sharding. To take advantage of this feature,
|
|
your test runner (not part of GoogleTest) needs to do the following:
|
|
|
|
1. Allocate a number of machines (shards) to run the tests.
|
|
1. On each shard, set the `GTEST_TOTAL_SHARDS` environment variable to the total
|
|
number of shards. It must be the same for all shards.
|
|
1. On each shard, set the `GTEST_SHARD_INDEX` environment variable to the index
|
|
of the shard. Different shards must be assigned different indices, which
|
|
must be in the range `[0, GTEST_TOTAL_SHARDS - 1]`.
|
|
1. Run the same test program on all shards. When GoogleTest sees the above two
|
|
environment variables, it will select a subset of the test functions to run.
|
|
Across all shards, each test function in the program will be run exactly
|
|
once.
|
|
1. Wait for all shards to finish, then collect and report the results.
|
|
|
|
Your project may have tests that were written without GoogleTest and thus don't
|
|
understand this protocol. In order for your test runner to figure out which test
|
|
supports sharding, it can set the environment variable `GTEST_SHARD_STATUS_FILE`
|
|
to a non-existent file path. If a test program supports sharding, it will create
|
|
this file to acknowledge that fact; otherwise it will not create it. The actual
|
|
contents of the file are not important at this time, although we may put some
|
|
useful information in it in the future.
|
|
|
|
Here's an example to make it clear. Suppose you have a test program `foo_test`
|
|
that contains the following 5 test functions:
|
|
|
|
```
|
|
TEST(A, V)
|
|
TEST(A, W)
|
|
TEST(B, X)
|
|
TEST(B, Y)
|
|
TEST(B, Z)
|
|
```
|
|
|
|
Suppose you have 3 machines at your disposal. To run the test functions in
|
|
parallel, you would set `GTEST_TOTAL_SHARDS` to 3 on all machines, and set
|
|
`GTEST_SHARD_INDEX` to 0, 1, and 2 on the machines respectively. Then you would
|
|
run the same `foo_test` on each machine.
|
|
|
|
GoogleTest reserves the right to change how the work is distributed across the
|
|
shards, but here's one possible scenario:
|
|
|
|
* Machine #0 runs `A.V` and `B.X`.
|
|
* Machine #1 runs `A.W` and `B.Y`.
|
|
* Machine #2 runs `B.Z`.
|
|
|
|
### Controlling Test Output
|
|
|
|
#### Colored Terminal Output
|
|
|
|
googletest can use colors in its terminal output to make it easier to spot the
|
|
important information:
|
|
|
|
<pre>...
|
|
<font color="green">[----------]</font> 1 test from FooTest
|
|
<font color="green">[ RUN ]</font> FooTest.DoesAbc
|
|
<font color="green">[ OK ]</font> FooTest.DoesAbc
|
|
<font color="green">[----------]</font> 2 tests from BarTest
|
|
<font color="green">[ RUN ]</font> BarTest.HasXyzProperty
|
|
<font color="green">[ OK ]</font> BarTest.HasXyzProperty
|
|
<font color="green">[ RUN ]</font> BarTest.ReturnsTrueOnSuccess
|
|
... some error messages ...
|
|
<font color="red">[ FAILED ]</font> BarTest.ReturnsTrueOnSuccess
|
|
...
|
|
<font color="green">[==========]</font> 30 tests from 14 test suites ran.
|
|
<font color="green">[ PASSED ]</font> 28 tests.
|
|
<font color="red">[ FAILED ]</font> 2 tests, listed below:
|
|
<font color="red">[ FAILED ]</font> BarTest.ReturnsTrueOnSuccess
|
|
<font color="red">[ FAILED ]</font> AnotherTest.DoesXyz
|
|
|
|
2 FAILED TESTS
|
|
</pre>
|
|
|
|
You can set the `GTEST_COLOR` environment variable or the `--gtest_color`
|
|
command line flag to `yes`, `no`, or `auto` (the default) to enable colors,
|
|
disable colors, or let googletest decide. When the value is `auto`, googletest
|
|
will use colors if and only if the output goes to a terminal and (on non-Windows
|
|
platforms) the `TERM` environment variable is set to `xterm` or `xterm-color`.
|
|
|
|
#### Suppressing test passes
|
|
|
|
By default, googletest prints 1 line of output for each test, indicating if it
|
|
passed or failed. To show only test failures, run the test program with
|
|
`--gtest_brief=1`, or set the GTEST_BRIEF environment variable to `1`.
|
|
|
|
#### Suppressing the Elapsed Time
|
|
|
|
By default, googletest prints the time it takes to run each test. To disable
|
|
that, run the test program with the `--gtest_print_time=0` command line flag, or
|
|
set the GTEST_PRINT_TIME environment variable to `0`.
|
|
|
|
#### Suppressing UTF-8 Text Output
|
|
|
|
In case of assertion failures, googletest prints expected and actual values of
|
|
type `string` both as hex-encoded strings as well as in readable UTF-8 text if
|
|
they contain valid non-ASCII UTF-8 characters. If you want to suppress the UTF-8
|
|
text because, for example, you don't have an UTF-8 compatible output medium, run
|
|
the test program with `--gtest_print_utf8=0` or set the `GTEST_PRINT_UTF8`
|
|
environment variable to `0`.
|
|
|
|
#### Generating an XML Report
|
|
|
|
googletest can emit a detailed XML report to a file in addition to its normal
|
|
textual output. The report contains the duration of each test, and thus can help
|
|
you identify slow tests.
|
|
|
|
To generate the XML report, set the `GTEST_OUTPUT` environment variable or the
|
|
`--gtest_output` flag to the string `"xml:path_to_output_file"`, which will
|
|
create the file at the given location. You can also just use the string `"xml"`,
|
|
in which case the output can be found in the `test_detail.xml` file in the
|
|
current directory.
|
|
|
|
If you specify a directory (for example, `"xml:output/directory/"` on Linux or
|
|
`"xml:output\directory\"` on Windows), googletest will create the XML file in
|
|
that directory, named after the test executable (e.g. `foo_test.xml` for test
|
|
program `foo_test` or `foo_test.exe`). If the file already exists (perhaps left
|
|
over from a previous run), googletest will pick a different name (e.g.
|
|
`foo_test_1.xml`) to avoid overwriting it.
|
|
|
|
The report is based on the `junitreport` Ant task. Since that format was
|
|
originally intended for Java, a little interpretation is required to make it
|
|
apply to googletest tests, as shown here:
|
|
|
|
```xml
|
|
<testsuites name="AllTests" ...>
|
|
<testsuite name="test_case_name" ...>
|
|
<testcase name="test_name" ...>
|
|
<failure message="..."/>
|
|
<failure message="..."/>
|
|
<failure message="..."/>
|
|
</testcase>
|
|
</testsuite>
|
|
</testsuites>
|
|
```
|
|
|
|
* The root `<testsuites>` element corresponds to the entire test program.
|
|
* `<testsuite>` elements correspond to googletest test suites.
|
|
* `<testcase>` elements correspond to googletest test functions.
|
|
|
|
For instance, the following program
|
|
|
|
```c++
|
|
TEST(MathTest, Addition) { ... }
|
|
TEST(MathTest, Subtraction) { ... }
|
|
TEST(LogicTest, NonContradiction) { ... }
|
|
```
|
|
|
|
could generate this report:
|
|
|
|
```xml
|
|
<?xml version="1.0" encoding="UTF-8"?>
|
|
<testsuites tests="3" failures="1" errors="0" time="0.035" timestamp="2011-10-31T18:52:42" name="AllTests">
|
|
<testsuite name="MathTest" tests="2" failures="1" errors="0" time="0.015">
|
|
<testcase name="Addition" status="run" time="0.007" classname="">
|
|
<failure message="Value of: add(1, 1)
 Actual: 3
Expected: 2" type="">...</failure>
|
|
<failure message="Value of: add(1, -1)
 Actual: 1
Expected: 0" type="">...</failure>
|
|
</testcase>
|
|
<testcase name="Subtraction" status="run" time="0.005" classname="">
|
|
</testcase>
|
|
</testsuite>
|
|
<testsuite name="LogicTest" tests="1" failures="0" errors="0" time="0.005">
|
|
<testcase name="NonContradiction" status="run" time="0.005" classname="">
|
|
</testcase>
|
|
</testsuite>
|
|
</testsuites>
|
|
```
|
|
|
|
Things to note:
|
|
|
|
* The `tests` attribute of a `<testsuites>` or `<testsuite>` element tells how
|
|
many test functions the googletest program or test suite contains, while the
|
|
`failures` attribute tells how many of them failed.
|
|
|
|
* The `time` attribute expresses the duration of the test, test suite, or
|
|
entire test program in seconds.
|
|
|
|
* The `timestamp` attribute records the local date and time of the test
|
|
execution.
|
|
|
|
* Each `<failure>` element corresponds to a single failed googletest
|
|
assertion.
|
|
|
|
#### Generating a JSON Report
|
|
|
|
googletest can also emit a JSON report as an alternative format to XML. To
|
|
generate the JSON report, set the `GTEST_OUTPUT` environment variable or the
|
|
`--gtest_output` flag to the string `"json:path_to_output_file"`, which will
|
|
create the file at the given location. You can also just use the string
|
|
`"json"`, in which case the output can be found in the `test_detail.json` file
|
|
in the current directory.
|
|
|
|
The report format conforms to the following JSON Schema:
|
|
|
|
```json
|
|
{
|
|
"$schema": "http://json-schema.org/schema#",
|
|
"type": "object",
|
|
"definitions": {
|
|
"TestCase": {
|
|
"type": "object",
|
|
"properties": {
|
|
"name": { "type": "string" },
|
|
"tests": { "type": "integer" },
|
|
"failures": { "type": "integer" },
|
|
"disabled": { "type": "integer" },
|
|
"time": { "type": "string" },
|
|
"testsuite": {
|
|
"type": "array",
|
|
"items": {
|
|
"$ref": "#/definitions/TestInfo"
|
|
}
|
|
}
|
|
}
|
|
},
|
|
"TestInfo": {
|
|
"type": "object",
|
|
"properties": {
|
|
"name": { "type": "string" },
|
|
"status": {
|
|
"type": "string",
|
|
"enum": ["RUN", "NOTRUN"]
|
|
},
|
|
"time": { "type": "string" },
|
|
"classname": { "type": "string" },
|
|
"failures": {
|
|
"type": "array",
|
|
"items": {
|
|
"$ref": "#/definitions/Failure"
|
|
}
|
|
}
|
|
}
|
|
},
|
|
"Failure": {
|
|
"type": "object",
|
|
"properties": {
|
|
"failures": { "type": "string" },
|
|
"type": { "type": "string" }
|
|
}
|
|
}
|
|
},
|
|
"properties": {
|
|
"tests": { "type": "integer" },
|
|
"failures": { "type": "integer" },
|
|
"disabled": { "type": "integer" },
|
|
"errors": { "type": "integer" },
|
|
"timestamp": {
|
|
"type": "string",
|
|
"format": "date-time"
|
|
},
|
|
"time": { "type": "string" },
|
|
"name": { "type": "string" },
|
|
"testsuites": {
|
|
"type": "array",
|
|
"items": {
|
|
"$ref": "#/definitions/TestCase"
|
|
}
|
|
}
|
|
}
|
|
}
|
|
```
|
|
|
|
The report uses the format that conforms to the following Proto3 using the
|
|
[JSON encoding](https://developers.google.com/protocol-buffers/docs/proto3#json):
|
|
|
|
```proto
|
|
syntax = "proto3";
|
|
|
|
package googletest;
|
|
|
|
import "google/protobuf/timestamp.proto";
|
|
import "google/protobuf/duration.proto";
|
|
|
|
message UnitTest {
|
|
int32 tests = 1;
|
|
int32 failures = 2;
|
|
int32 disabled = 3;
|
|
int32 errors = 4;
|
|
google.protobuf.Timestamp timestamp = 5;
|
|
google.protobuf.Duration time = 6;
|
|
string name = 7;
|
|
repeated TestCase testsuites = 8;
|
|
}
|
|
|
|
message TestCase {
|
|
string name = 1;
|
|
int32 tests = 2;
|
|
int32 failures = 3;
|
|
int32 disabled = 4;
|
|
int32 errors = 5;
|
|
google.protobuf.Duration time = 6;
|
|
repeated TestInfo testsuite = 7;
|
|
}
|
|
|
|
message TestInfo {
|
|
string name = 1;
|
|
enum Status {
|
|
RUN = 0;
|
|
NOTRUN = 1;
|
|
}
|
|
Status status = 2;
|
|
google.protobuf.Duration time = 3;
|
|
string classname = 4;
|
|
message Failure {
|
|
string failures = 1;
|
|
string type = 2;
|
|
}
|
|
repeated Failure failures = 5;
|
|
}
|
|
```
|
|
|
|
For instance, the following program
|
|
|
|
```c++
|
|
TEST(MathTest, Addition) { ... }
|
|
TEST(MathTest, Subtraction) { ... }
|
|
TEST(LogicTest, NonContradiction) { ... }
|
|
```
|
|
|
|
could generate this report:
|
|
|
|
```json
|
|
{
|
|
"tests": 3,
|
|
"failures": 1,
|
|
"errors": 0,
|
|
"time": "0.035s",
|
|
"timestamp": "2011-10-31T18:52:42Z",
|
|
"name": "AllTests",
|
|
"testsuites": [
|
|
{
|
|
"name": "MathTest",
|
|
"tests": 2,
|
|
"failures": 1,
|
|
"errors": 0,
|
|
"time": "0.015s",
|
|
"testsuite": [
|
|
{
|
|
"name": "Addition",
|
|
"status": "RUN",
|
|
"time": "0.007s",
|
|
"classname": "",
|
|
"failures": [
|
|
{
|
|
"message": "Value of: add(1, 1)\n Actual: 3\nExpected: 2",
|
|
"type": ""
|
|
},
|
|
{
|
|
"message": "Value of: add(1, -1)\n Actual: 1\nExpected: 0",
|
|
"type": ""
|
|
}
|
|
]
|
|
},
|
|
{
|
|
"name": "Subtraction",
|
|
"status": "RUN",
|
|
"time": "0.005s",
|
|
"classname": ""
|
|
}
|
|
]
|
|
},
|
|
{
|
|
"name": "LogicTest",
|
|
"tests": 1,
|
|
"failures": 0,
|
|
"errors": 0,
|
|
"time": "0.005s",
|
|
"testsuite": [
|
|
{
|
|
"name": "NonContradiction",
|
|
"status": "RUN",
|
|
"time": "0.005s",
|
|
"classname": ""
|
|
}
|
|
]
|
|
}
|
|
]
|
|
}
|
|
```
|
|
|
|
{: .callout .important}
|
|
IMPORTANT: The exact format of the JSON document is subject to change.
|
|
|
|
### Controlling How Failures Are Reported
|
|
|
|
#### Detecting Test Premature Exit
|
|
|
|
Google Test implements the _premature-exit-file_ protocol for test runners to
|
|
catch any kind of unexpected exits of test programs. Upon start, Google Test
|
|
creates the file which will be automatically deleted after all work has been
|
|
finished. Then, the test runner can check if this file exists. In case the file
|
|
remains undeleted, the inspected test has exited prematurely.
|
|
|
|
This feature is enabled only if the `TEST_PREMATURE_EXIT_FILE` environment
|
|
variable has been set.
|
|
|
|
#### Turning Assertion Failures into Break-Points
|
|
|
|
When running test programs under a debugger, it's very convenient if the
|
|
debugger can catch an assertion failure and automatically drop into interactive
|
|
mode. googletest's *break-on-failure* mode supports this behavior.
|
|
|
|
To enable it, set the `GTEST_BREAK_ON_FAILURE` environment variable to a value
|
|
other than `0`. Alternatively, you can use the `--gtest_break_on_failure`
|
|
command line flag.
|
|
|
|
#### Disabling Catching Test-Thrown Exceptions
|
|
|
|
googletest can be used either with or without exceptions enabled. If a test
|
|
throws a C++ exception or (on Windows) a structured exception (SEH), by default
|
|
googletest catches it, reports it as a test failure, and continues with the next
|
|
test method. This maximizes the coverage of a test run. Also, on Windows an
|
|
uncaught exception will cause a pop-up window, so catching the exceptions allows
|
|
you to run the tests automatically.
|
|
|
|
When debugging the test failures, however, you may instead want the exceptions
|
|
to be handled by the debugger, such that you can examine the call stack when an
|
|
exception is thrown. To achieve that, set the `GTEST_CATCH_EXCEPTIONS`
|
|
environment variable to `0`, or use the `--gtest_catch_exceptions=0` flag when
|
|
running the tests.
|
|
|
|
### Sanitizer Integration
|
|
|
|
The
|
|
[Undefined Behavior Sanitizer](https://clang.llvm.org/docs/UndefinedBehaviorSanitizer.html),
|
|
[Address Sanitizer](https://github.com/google/sanitizers/wiki/AddressSanitizer),
|
|
and
|
|
[Thread Sanitizer](https://github.com/google/sanitizers/wiki/ThreadSanitizerCppManual)
|
|
all provide weak functions that you can override to trigger explicit failures
|
|
when they detect sanitizer errors, such as creating a reference from `nullptr`.
|
|
To override these functions, place definitions for them in a source file that
|
|
you compile as part of your main binary:
|
|
|
|
```
|
|
extern "C" {
|
|
void __ubsan_on_report() {
|
|
FAIL() << "Encountered an undefined behavior sanitizer error";
|
|
}
|
|
void __asan_on_error() {
|
|
FAIL() << "Encountered an address sanitizer error";
|
|
}
|
|
void __tsan_on_report() {
|
|
FAIL() << "Encountered a thread sanitizer error";
|
|
}
|
|
} // extern "C"
|
|
```
|
|
|
|
After compiling your project with one of the sanitizers enabled, if a particular
|
|
test triggers a sanitizer error, googletest will report that it failed.
|