googletest 笔记

谓词断言能比 EXPECT_TRUE 提供更详细的错误消息；
EXPECT_PRED1( pred , val1 ) \
EXPECT_PRED2( pred , val1 , val2 ) \
EXPECT_PRED3( pred , val1 , val2 , val3 ) \
EXPECT_PRED4( pred , val1 , val2 , val3 , val4 ) \
EXPECT_PRED5( pred , val1 , val2 , val3 , val4 , val5 )
ASSERT_PRED1( pred , val1 ) \
ASSERT_PRED2( pred , val1 , val2 ) \
ASSERT_PRED3( pred , val1 , val2 , val3 ) \
ASSERT_PRED4( pred , val1 , val2 , val3 , val4 ) \
ASSERT_PRED5( pred , val1 , val2 , val3 , val4 , val5 )
// Returns true if m and n have no common divisors
except 1.
bool MutuallyPrime(int m, int n) { ... }
...
const int a = 3;
const int b = 4;
const int c = 10;
...
EXPECT_PRED2(MutuallyPrime, a, b);  // Succeeds
EXPECT_PRED2(MutuallyPrime, b, c);  // Fails
能得到错误信息：
MutuallyPrime(b, c) is false, where
b is 4
c is 10

// 定义类型，继承自 testing::Test
class TestFixtureSmpl : public testing::Test {
protected:
 void SetUp() {} // 测试夹具测试前调用的函数 -- 做初
始化的工作
    void TearDown() {} // 测试夹具测试后调用的函数 --
做清理的工作
};
// 需要在 TEST_F 中书写测试用例
#define TEST_F(test_fixture,test_name)
// 如果需要复用测试夹具，只需要继承自 TestFixtureSmpl
class TestFixtureSmpl_v2 : public TestFixtureSmpl
{
};

有时候相同的接口，有多个实现，下面是复用测试代码流程；复用测试案例，策略模式 
using testing::Test;
using testing::Types;
// 先申明测试夹具
template <class T>
class TestFixtureSmpl : public testing::Test {
protected:
 void SetUp() {} // 测试夹具测试前调用的函数 -- 做初
始化的工作
    void TearDown() {} // 测试夹具测试后调用的函数 --
做清理的工作
};
// 枚举测试类型
typedef Types<Class1, Class2, class3, ...>
Implementations;
// #define
TYPED_TEST_SUITE(CaseName,Types,__VA_ARGS__...)
// 注意 casename 一定要与测试夹具的名字一致
TYPED_TEST_SUITE(TestFixtureSmpl,
Implementations);
// #define TYPED_TEST(CaseName,TestName)
// 开始测试， CaseName 要与 TYPED_TEST_SUITE 一致
TYPED_TEST(TestFixtureSmpl, TestName)
有时候你写了某个接口，期望其他人实现它，你可能想写一系列测试，确保其他人的实现满足你的测试；
// 首先声明测试类型参数化(_P 是 parameterized or
pattern)
// #define TYPED_TEST_SUITE_P(SuiteName)
TYPED_TEST_SUITE_P(TestFixtureSmpl);
// 书写测试, suiteName 与上面一致
// #define TYPED_TEST_P(SuiteName,TestName)
TYPED_TEST_P(TestFixtureSmpl,TestName)
// 枚举所有测试
// #define
REGISTER_TYPED_TEST_SUITE_P(SuiteName,__VA_ARGS__
...)
REGISTER_TYPED_TEST_SUITE_P(TestFixtureSmpl,
TestName1,TestName2,...)
// 上面定义的是抽象测试类型
// 其他人实现功能后，开始测试，假如实现了
OnTheFlyPrimeTable 和 PreCalculatedPrimeTable
typedef Types<OnTheFlyPrimeTable,
PreCalculatedPrimeTable>
    PrimeTableImplementations;
// #define
INSTANTIATE_TYPED_TEST_SUITE_P(Prefix,SuiteName,T
ypes,__VA_ARGS__...)
INSTANTIATE_TYPED_TEST_SUITE_P(
 instance_name,
 testcase,
 typelist...)

可以通过 googletest 的事件机制，在测试前后进行埋点处理；
// The interface for tracing execution of tests.
The methods are organized in
// the order the corresponding events are fired.
class TestEventListener {
public:
  virtual ~TestEventListener() {}
  // Fired before any test activity starts.
  virtual void OnTestProgramStart(const UnitTest& unit_test) = 0;
  // Fired before each iteration of tests starts. There may be more than
  // one iteration if GTEST_FLAG(repeat) is set. iteration is the iteration
  // index, starting from 0.
  virtual void OnTestIterationStart(const UnitTest& unit_test,int iteration) = 0;
// Fired before environment set-up for eachiteration of tests starts.
  virtual void OnEnvironmentsSetUpStart(const UnitTest& unit_test) = 0;
  // Fired after environment set-up for eachiteration of tests ends.
  virtual void OnEnvironmentsSetUpEnd(const UnitTest& unit_test) = 0;
  // Fired before the test suite starts.
  virtual void OnTestSuiteStart(const TestSuite& /*test_suite*/) {}
  // Legacy API is deprecated but still available
#ifndef GTEST_REMOVE_LEGACY_TEST_CASEAPI_
  virtual void OnTestCaseStart(const TestCase& /*test_case*/) {}
#endif  // GTEST_REMOVE_LEGACY_TEST_CASEAPI_
  // Fired before the test starts.
  virtual void OnTestStart(const TestInfo& test_info) = 0;
  // Fired after a failed assertion or a SUCCEED() invocation.
  // If you want to throw an exception from this function to skip to the next
  // TEST, it must be AssertionException defined above, or inherited from it.
  virtual void OnTestPartResult(const TestPartResult& test_part_result) = 0;
  // Fired after the test ends.
 virtual void OnTestEnd(const TestInfo& test_info) = 0;
  // Fired after the test suite ends.
  virtual void OnTestSuiteEnd(const TestSuite& /*test_suite*/) {}
  // Legacy API is deprecated but still available
#ifndef GTEST_REMOVE_LEGACY_TEST_CASEAPI_
  virtual void OnTestCaseEnd(const TestCase& /*test_case*/) {}
#endif  // GTEST_REMOVE_LEGACY_TEST_CASEAPI_
  // Fired before environment tear-down for each iteration of tests starts.
  virtual void OnEnvironmentsTearDownStart(const UnitTest& unit_test) = 0;
  // Fired after environment tear-down for each iteration of tests ends.
  virtual void OnEnvironmentsTearDownEnd(const UnitTest& unit_test) = 0;
  // Fired after each iteration of tests finishes.
  virtual void OnTestIterationEnd(const UnitTest& unit_test,int iteration) = 0;
  // Fired after all test activities have ended.
  virtual void OnTestProgramEnd(const UnitTest& unit_test) = 0;
};

// 重载操作符 new 和 delete，接着用类的静态成员来统计调
用 new 和 delete的次数
class CLeakMem {
public:
  // ...
  void* operator new(size_t allocation_size) {
    allocated_++;
    return malloc(allocation_size);
 }
  void operator delete(void* block, size_t /*
allocation_size */) {
    allocated_--;
    free(block);
 }
private:
  static int allocated_;
};
int CLeakMem::allocated_ = 0;

检测
class LeakChecker : public EmptyTestEventListener
{
private:
  // Called before a test starts.
  void OnTestStart(const TestInfo& /* test_info*/) override {
    initially_allocated_ = CLeakMem::allocated();
 }
  // Called after a test ends.
  void OnTestEnd(const TestInfo& /* test_info */) override {
    int difference = CLeakMem::allocated() - initially_allocated_;
    // You can generate a failure in any event handler except
    // OnTestPartResult. Just use an appropriate Google Test assertion to do
    // it.
    EXPECT_LE(difference, 0) << "Leaked " << difference << " unit(s) of class!";
  }
  int initially_allocated_;
};