Implements the MATCHER* macros.
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zhanyong.wan
@@ -47,6 +47,14 @@ $var n = 10 $$ The maximum arity we support.
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namespace testing {
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namespace internal {
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// Generates a non-fatal failure iff 'description' is not a valid
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// matcher description.
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inline void ValidateMatcherDescription(const char* description) {
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EXPECT_STREQ("", description)
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<< "The description string in a MATCHER*() macro must be \"\" "
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"at this moment. We will implement custom description string soon.";
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}
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// Implements ElementsAre() and ElementsAreArray().
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template <typename Container>
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class ElementsAreMatcherImpl : public MatcherInterface<Container> {
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@@ -300,4 +308,206 @@ ElementsAreArray(const T (&array)[N]) {
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} // namespace testing
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// The MATCHER* family of macros can be used in a namespace scope to
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// define custom matchers easily. The syntax:
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//
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// MATCHER(name, description_string) { statements; }
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//
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// will define a matcher with the given name that executes the
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// statements, which must return a bool to indicate if the match
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// succeeds. For now, the description_string must be "", but we'll
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// allow other values soon. Inside the statements, you can refer to
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// the value being matched by 'arg', and refer to its type by
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// 'arg_type'. For example:
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//
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// MATCHER(IsEven, "") { return (arg % 2) == 0; }
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//
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// allows you to write
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//
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// // Expects mock_foo.Bar(n) to be called where n is even.
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// EXPECT_CALL(mock_foo, Bar(IsEven()));
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//
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// or,
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//
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// // Verifies that the value of some_expression is even.
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// EXPECT_THAT(some_expression, IsEven());
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//
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// If the above assertion fails, it will print something like:
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//
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// Value of: some_expression
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// Expected: is even
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// Actual: 7
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//
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// where the description "is even" is automatically calculated from the
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// matcher name IsEven.
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//
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// Note that the type of the value being matched (arg_type) is
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// determined by the context in which you use the matcher and is
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// supplied to you by the compiler, so you don't need to worry about
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// declaring it (nor can you). This allows the matcher to be
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// polymorphic. For example, IsEven() can be used to match any type
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// where the value of "(arg % 2) == 0" can be implicitly converted to
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// a bool. In the "Bar(IsEven())" example above, if method Bar()
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// takes an int, 'arg_type' will be int; if it takes an unsigned long,
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// 'arg_type' will be unsigned long; and so on.
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//
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// Sometimes you'll want to parameterize the matcher. For that you
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// can use another macro:
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//
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// MATCHER_P(name, param_name, description_string) { statements; }
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//
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// For example:
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//
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// MATCHER_P(HasAbsoluteValue, value, "") { return abs(arg) == value; }
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//
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// will allow you to write:
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//
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// EXPECT_THAT(Blah("a"), HasAbsoluteValue(n));
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//
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// which may lead to this message (assuming n is 10):
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//
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// Value of: Blah("a")
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// Expected: has absolute value 10
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// Actual: -9
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//
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// Note that both the matcher description and its parameter are
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// printed, making the message human-friendly.
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//
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// In the matcher definition body, you can write 'foo_type' to
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// reference the type of a parameter named 'foo'. For example, in the
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// body of MATCHER_P(HasAbsoluteValue, value) above, you can write
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// 'value_type' to refer to the type of 'value'.
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//
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// We also provide MATCHER_P2, MATCHER_P3, ..., up to MATCHER_P$n to
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// support multi-parameter matchers.
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//
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// For the purpose of typing, you can view
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//
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// MATCHER_Pk(Foo, p1, ..., pk, description_string) { ... }
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//
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// as shorthand for
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//
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// template <typename p1_type, ..., typename pk_type>
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// FooMatcherPk<p1_type, ..., pk_type>
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// Foo(p1_type p1, ..., pk_type pk) { ... }
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//
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// When you write Foo(v1, ..., vk), the compiler infers the types of
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// the parameters v1, ..., and vk for you. If you are not happy with
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// the result of the type inference, you can specify the types by
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// explicitly instantiating the template, as in Foo<long, bool>(5,
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// false). As said earlier, you don't get to (or need to) specify
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// 'arg_type' as that's determined by the context in which the matcher
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// is used. You can assign the result of expression Foo(p1, ..., pk)
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// to a variable of type FooMatcherPk<p1_type, ..., pk_type>. This
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// can be useful when composing matchers.
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//
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// While you can instantiate a matcher template with reference types,
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// passing the parameters by pointer usually makes your code more
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// readable. If, however, you still want to pass a parameter by
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// reference, be aware that in the failure message generated by the
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// matcher you will see the value of the referenced object but not its
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// address.
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//
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// You can overload matchers with different numbers of parameters:
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//
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// MATCHER_P(Blah, a, description_string1) { ... }
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// MATCHER_P2(Blah, a, b, description_string2) { ... }
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//
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// While it's tempting to always use the MATCHER* macros when defining
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// a new matcher, you should also consider implementing
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// MatcherInterface or using MakePolymorphicMatcher() instead,
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// especially if you need to use the matcher a lot. While these
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// approaches require more work, they give you more control on the
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// types of the value being matched and the matcher parameters, which
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// in general leads to better compiler error messages that pay off in
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// the long run. They also allow overloading matchers based on
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// parameter types (as opposed to just based on the number of
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// parameters).
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//
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// CAVEAT:
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//
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// MATCHER*() can only be used in a namespace scope. The reason is
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// that C++ doesn't yet allow function-local types to be used to
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// instantiate templates. The up-coming C++0x standard will fix this.
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// Once that's done, we'll consider supporting using MATCHER*() inside
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// a function.
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//
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// MORE INFORMATION:
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//
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// To learn more about using these macros, please search for 'MATCHER'
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// on http://code.google.com/p/googlemock/wiki/CookBook.
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$range i 0..n
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$for i
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[[
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$var macro_name = [[$if i==0 [[MATCHER]] $elif i==1 [[MATCHER_P]]
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$else [[MATCHER_P$i]]]]
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$var class_name = [[name##Matcher[[$if i==0 [[]] $elif i==1 [[P]]
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$else [[P$i]]]]]]
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$range j 0..i-1
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$var template = [[$if i==0 [[]] $else [[
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template <$for j, [[typename p$j##_type]]>\
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]]]]
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$var ctor_param_list = [[$for j, [[p$j##_type gmock_p$j]]]]
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$var inits = [[$if i==0 [[]] $else [[ : $for j, [[p$j(gmock_p$j)]]]]]]
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$var params = [[$for j, [[p$j]]]]
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$var param_types = [[$if i==0 [[]] $else [[<$for j, [[p$j##_type]]>]]]]
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$var param_types_and_names = [[$for j, [[p$j##_type p$j]]]]
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$var param_field_decls = [[$for j
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[[
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p$j##_type p$j;\
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]]]]
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$var param_field_decls2 = [[$for j
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[[
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p$j##_type p$j;\
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]]]]
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#define $macro_name(name$for j [[, p$j]], description)\$template
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class $class_name {\
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public:\
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template <typename arg_type>\
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class gmock_Impl : public ::testing::MatcherInterface<arg_type> {\
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public:\
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[[$if i==1 [[explicit ]]]]gmock_Impl($ctor_param_list)$inits {}\
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virtual bool Matches(arg_type arg) const;\
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virtual void DescribeTo(::std::ostream* os) const {\
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*os << ::testing::internal::ConvertIdentifierNameToWords(#name);\
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[[$if i==1 [[ *os << " ";\
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::testing::internal::UniversalPrint(p0, os);\
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]] $elif i>=2 [[ *os << " (";\
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::testing::internal::UniversalPrint(p0, os);\
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$range k 1..i-1
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$for k [[
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*os << ", ";\
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::testing::internal::UniversalPrint(p$k, os);\
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]]
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*os << ")";\
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]]]]
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}\$param_field_decls
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};\
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template <typename arg_type>\
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operator ::testing::Matcher<arg_type>() const {\
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return ::testing::Matcher<arg_type>(new gmock_Impl<arg_type>($params));\
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}\
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$class_name($ctor_param_list)$inits {\
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::testing::internal::ValidateMatcherDescription(description);\
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}\$param_field_decls2
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};\$template
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inline $class_name$param_types name($param_types_and_names) {\
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return $class_name$param_types($params);\
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}\$template
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template <typename arg_type>\
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bool $class_name$param_types::\
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gmock_Impl<arg_type>::Matches(arg_type arg) const
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]]
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#endif // GMOCK_INCLUDE_GMOCK_GMOCK_GENERATED_MATCHERS_H_
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