gtest’s API
gtest里有三种使用方式，分别是 TEST, TEST_F, TESTP, 都是宏定义。
TEST的定义
TEST的定义如下，
// Defines a test.
//
// The first parameter is the name of the test case, and the second
// parameter is the name of the test within the test case.
//
// The convention is to end the test case name with "Test". For
// example, a test case for the Foo class can be named FooTest.
//
// Test code should appear between braces after an invocation of
// this macro. Example:
//
// TEST(FooTest, InitializesCorrectly) {
// Foo foo;
// EXPECT_TRUE(foo.StatusIsOK());
// }
// Note that we call GetTestTypeId() instead of GetTypeId<
// ::testing::Test>() here to get the type ID of testing::Test. This
// is to work around a suspected linker bug when using Google Test as
// a framework on Mac OS X. The bug causes GetTypeId<
// ::testing::Test>() to return different values depending on whether
// the call is from the Google Test framework itself or from user test
// code. GetTestTypeId() is guaranteed to always return the same
// value, as it always calls GetTypeId<>() from the Google Test
// framework.
#define GTEST_TEST(test_case_name, test_name)\
GTEST_TEST_(test_case_name, test_name, \
::testing::Test, ::testing::internal::GetTestTypeId())
// Define this macro to 1 to omit the definition of TEST(), which
// is a generic name and clashes with some other libraries.
#if !GTEST_DONT_DEFINE_TEST
# define TEST(test_case_name, test_name) GTEST_TEST(test_case_name, test_name)
#endif
上面的GTEST_TEST_宏定义如下:
// Expands to the name of the class that implements the given test.
#define GTEST_TEST_CLASS_NAME_(test_case_name, test_name) \
test_case_name##_##test_name##_Test
// Helper macro for defining tests.
#define GTEST_TEST_(test_case_name, test_name, parent_class, parent_id)\
class GTEST_TEST_CLASS_NAME_(test_case_name, test_name) : public parent_class {\
public:\
GTEST_TEST_CLASS_NAME_(test_case_name, test_name)() {}\
private:\
virtual void TestBody();\
static ::testing::TestInfo* const test_info_ GTEST_ATTRIBUTE_UNUSED_;\
GTEST_DISALLOW_COPY_AND_ASSIGN_(\
GTEST_TEST_CLASS_NAME_(test_case_name, test_name));\
};\
\
::testing::TestInfo* const GTEST_TEST_CLASS_NAME_(test_case_name, test_name)\
::test_info_ =\
::testing::internal::MakeAndRegisterTestInfo(\
#test_case_name, #test_name, NULL, NULL, \
(parent_id), \
parent_class::SetUpTestCase, \
parent_class::TearDownTestCase, \
new ::testing::internal::TestFactoryImpl<\
GTEST_TEST_CLASS_NAME_(test_case_name, test_name)>);\
void GTEST_TEST_CLASS_NAME_(test_case_name, test_name)::TestBody()
通过上面代码， 我们可以看到，
通过TEST，我们实际是定义了一个以test_case_name,test_name组成的class,
并继承自Test,然后TEST后面代码实际是这个class里TestBody的函数体。
TEST_F宏定义
// Defines a test that uses a test fixture.
//
// The first parameter is the name of the test fixture class, which
// also doubles as the test case name. The second parameter is the
// name of the test within the test case.
//
// A test fixture class must be declared earlier. The user should put
// his test code between braces after using this macro. Example:
//
// class FooTest : public testing::Test {
// protected:
// virtual void SetUp() { b_.AddElement(3); }
//
// Foo a_;
// Foo b_;
// };
//
// TEST_F(FooTest, InitializesCorrectly) {
// EXPECT_TRUE(a_.StatusIsOK());
// }
//
// TEST_F(FooTest, ReturnsElementCountCorrectly) {
// EXPECT_EQ(0, a_.size());
// EXPECT_EQ(1, b_.size());
// }
#define TEST_F(test_fixture, test_name)\
GTEST_TEST_(test_fixture, test_name, test_fixture, \
::testing::internal::GetTypeId<test_fixture>())
} // namespace testing
其实TEST_F与上面TEST类似，上面主要不同就是TEST直接继承Test，而TEST_F需要test_fixture先继承Test,
然后test_fixture,test_case组成的class再继承test_fixture，
也就是通过这种方式我们可以用过在test_fixture里override来定制化操作。
TEST_P定义
TEST_P的宏定义具体如下:
# define TEST_P(test_case_name, test_name) \
class GTEST_TEST_CLASS_NAME_(test_case_name, test_name) \
: public test_case_name { \
public: \
GTEST_TEST_CLASS_NAME_(test_case_name, test_name)() {} \
virtual void TestBody(); \
private: \
static int AddToRegistry() { \
::testing::UnitTest::GetInstance()->parameterized_test_registry(). \
GetTestCasePatternHolder<test_case_name>(\
#test_case_name, __FILE__, __LINE__)->AddTestPattern(\
#test_case_name, \
#test_name, \
new ::testing::internal::TestMetaFactory< \
GTEST_TEST_CLASS_NAME_(test_case_name, test_name)>()); \
return 0; \
} \
static int gtest_registering_dummy_ GTEST_ATTRIBUTE_UNUSED_; \
GTEST_DISALLOW_COPY_AND_ASSIGN_(\
GTEST_TEST_CLASS_NAME_(test_case_name, test_name)); \
}; \
int GTEST_TEST_CLASS_NAME_(test_case_name, \
test_name)::gtest_registering_dummy_ = \
GTEST_TEST_CLASS_NAME_(test_case_name, test_name)::AddToRegistry(); \
void GTEST_TEST_CLASS_NAME_(test_case_name, test_name)::TestBody()
与TEST_F类似， 定义的test_case_name首先需要定义为一个继承了Test和WithParamInterface的class，不过一般只需要继承TestWithParam即可
TestWithParam与Test，WithParamInterface关系如下代码所示:
// The pure interface class that all value-parameterized tests inherit from.
// A value-parameterized class must inherit from both ::testing::Test and
// ::testing::WithParamInterface. In most cases that just means inheriting
// from ::testing::TestWithParam, but more complicated test hierarchies
// may need to inherit from Test and WithParamInterface at different levels.
//
// This interface has support for accessing the test parameter value via
// the GetParam() method.
//
// Use it with one of the parameter generator defining functions, like Range(),
// Values(), ValuesIn(), Bool(), and Combine().
//
// class FooTest : public ::testing::TestWithParam<int> {
// protected:
// FooTest() {
// // Can use GetParam() here.
// }
// virtual ~FooTest() {
// // Can use GetParam() here.
// }
// virtual void SetUp() {
// // Can use GetParam() here.
// }
// virtual void TearDown {
// // Can use GetParam() here.
// }
// };
// TEST_P(FooTest, DoesBar) {
// // Can use GetParam() method here.
// Foo foo;
// ASSERT_TRUE(foo.DoesBar(GetParam()));
// }
// INSTANTIATE_TEST_CASE_P(OneToTenRange, FooTest, ::testing::Range(1, 10));
template <typename T>
class WithParamInterface
// Most value-parameterized classes can ignore the existence of
// WithParamInterface, and can just inherit from ::testing::TestWithParam.
template <typename T>
class TestWithParam : public Test, public WithParamInterface<T> {
};
上面的TestBody里可以使用GetParam()来使用后面INSTANTIATE_TEST_CASE_P(prefix, test_case_name, generator)里generator里传递进来的参数。通过INSTANTIATE_TEST_CASE_P(prefix, test_case_name, generator)来定义需要传递的参数
# define INSTANTIATE_TEST_CASE_P(prefix, test_case_name, generator) \
::testing::internal::ParamGenerator<test_case_name::ParamType> \
gtest_##prefix##test_case_name##_EvalGenerator_() { return generator; } \
int gtest_##prefix##test_case_name##_dummy_ = \
::testing::UnitTest::GetInstance()->parameterized_test_registry(). \
GetTestCasePatternHolder<test_case_name>(\
#test_case_name, __FILE__, __LINE__)->AddTestCaseInstantiation(\
#prefix, \
>est_##prefix##test_case_name##_EvalGenerator_, \
__FILE__, __LINE__)
}
产生参数可以用Values和Range，Values是使用指定的参数列表， 而Range则是在指定的范围内按指定的步长来产生参数， 其中Values代码如下:
// Values() allows generating tests from explicitly specified list of
// parameters.
//
// Synopsis:
// Values(T v1, T v2, ..., T vN)
// - returns a generator producing sequences with elements v1, v2, ..., vN.
// Currently, Values() supports from 1 to 50 parameters.
//
template <typename T1>
internal::ValueArray1<T1> Values(T1 v1) {
return internal::ValueArray1<T1>(v1);
}
gtest执行流程
使用上面的Test, TEST_F或TEST_P定义好test_case和test之后， 就需要在main函数里顺序执行InitGoogleTest来初始化gtest测试框架，然后调用RUN_ALL_TESTS来执行所有的测试。
// Initializes Google Test. This must be called before calling
// RUN_ALL_TESTS(). In particular, it parses a command line for the
// flags that Google Test recognizes. Whenever a Google Test flag is
// seen, it is removed from argv, and *argc is decremented.
//
// No value is returned. Instead, the Google Test flag variables are
// updated.
//
// Calling the function for the second time has no user-visible effect.
GTEST_API_ void InitGoogleTest(int* argc, char** argv);
// Use this function in main() to run all tests. It returns 0 if all
// tests are successful, or 1 otherwise.
//
// RUN_ALL_TESTS() should be invoked after the command line has been
// parsed by InitGoogleTest().
//
// This function was formerly a macro; thus, it is in the global
// namespace and has an all-caps name.
int RUN_ALL_TESTS() GTEST_MUST_USE_RESULT_;
inline int RUN_ALL_TESTS() {
return ::testing::UnitTest::GetInstance()->Run();
}
gtest基本类
上面我们使用的不管是TEST,TEST_F还是TEST_P最终都继承了Test类。在gtest里，Test是所有test都要继承的基类
// The abstract class that all tests inherit from.
//
// In Google Test, a unit test program contains one or many TestCases, and
// each TestCase contains one or many Tests.
//
// When you define a test using the TEST macro, you don't need to
// explicitly derive from Test - the TEST macro automatically does
// this for you.
//
// The only time you derive from Test is when defining a test fixture
// to be used a TEST_F. For example:
//
// class FooTest : public testing::Test {
// protected:
// void SetUp() override { ... }
// void TearDown() override { ... }
// ...
// };
//
// TEST_F(FooTest, Bar) { ... }
// TEST_F(FooTest, Baz) { ... }
//
// Test is not copyable.
class GTEST_API_ Test
gtest提供了一系列的EXPECT_*和ASSERT_*，EXPECT_*比较fail之后会继续执行后面的代码， 而ASSERT_*失败之后会停止执行。
其具体实现如下所示:
// Boolean assertions. Condition can be either a Boolean expression or an
// AssertionResult. For more information on how to use AssertionResult with
// these macros see comments on that class.
#define EXPECT_TRUE(condition) \
GTEST_TEST_BOOLEAN_(condition, #condition, false, true, \
GTEST_NONFATAL_FAILURE_)
#define EXPECT_FALSE(condition) \
GTEST_TEST_BOOLEAN_(!(condition), #condition, true, false, \
GTEST_NONFATAL_FAILURE_)
#define ASSERT_TRUE(condition) \
GTEST_TEST_BOOLEAN_(condition, #condition, false, true, \
GTEST_FATAL_FAILURE_)
#define ASSERT_FALSE(condition) \
GTEST_TEST_BOOLEAN_(!(condition), #condition, true, false, \
GTEST_FATAL_FAILURE_)
// Implements Boolean test assertions such as EXPECT_TRUE. expression can be
// either a boolean expression or an AssertionResult. text is a textual
// represenation of expression as it was passed into the EXPECT_TRUE.
#define GTEST_TEST_BOOLEAN_(expression, text, actual, expected, fail) \
GTEST_AMBIGUOUS_ELSE_BLOCKER_ \
if (const ::testing::AssertionResult gtest_ar_ = \
::testing::AssertionResult(expression)) \
; \
else \
fail(::testing::internal::GetBoolAssertionFailureMessage(\
gtest_ar_, text, #actual, #expected).c_str())
测试实例
简单使用TEST,TEST_F,TEST_P的测试代码:
#include "gtest.h"
/*
* TEST example
*/
TEST(test, EXPECT) {
EXPECT_TRUE(1);
}
/*
* TEST_F test example
*/
class testFixture : public testing::Test {};
TEST_F(testFixture, AssertEQ) {
ASSERT_EQ(5, 5);
}
TEST_F(testFixture, AssertTrue) {
ASSERT_TRUE(true);
ASSERT_TRUE(false) << "failure example";
}
/* ------------------------- */
/*
* TEST_P test example
*/
class testParameter : public testing::TestWithParam<int> {};
TEST_P(testParameter, TrueOrFalse) {
auto para = GetParam();
EXPECT_TRUE(para%2 == 0);
}
INSTANTIATE_TEST_CASE_P(
Values, testParameter, ::testing::Values(2,4)
);
INSTANTIATE_TEST_CASE_P(
Range, testParameter, ::testing::Range(6,8,2)
);
/* ------------------------- */
int main(int argc, char** argv) {
::testing::InitGoogleTest(&argc, argv);
return RUN_ALL_TESTS();
}
测试输出 ：
