Googlemock 暂停预期答案

【问题标题】：Googlemock Pause ExpectationsGooglemock 暂停预期
【发布时间】：2021-05-12 07:24:11
【问题描述】：

我有一个场景，我希望对模拟对象上的函数进行一些调用，然后对于某些代码路径，我需要确保不调用该函数，然后再调用它。有没有办法做到这一点？

EXPECT_CALL(mockObj, 1); 
foo(1);

// Expect this call at the first invocation of foo(2)
EXPECT_CALL(mockObj, 2); 
foo(2);

// These calls should not call my mockObj again, the above expectation is 
// intended for the first invocation of foo(2)
foo(2);
foo(2);

// And now, i expect it to be called
EXPECT_CALL(mockObj, 3); 
foo(3);

我可能会检查 EXPECT_CALL(mockObj, 2);只调用了预期的次数，但我还想确认它仅在第一次调用 foo(2) 时调用，而不是在随后调用 foo(2) 时调用。你能告诉我在 gmock 中实现这一点的任何方法吗？

【问题讨论】：

RetiresOnSaturation 可能会有所帮助。

标签： c++ googletest googlemock

【解决方案1】：

Gmock cookbook 建议使用虚拟检查点模拟函数

using ::testing::MockFunction;

TEST(FooTest, InvokesMyMockCorrectly) {
  MyMock mockObj;
  // Class MockFunction<F> has exactly one mock method.  It is named
  // Call() and has type F.
  MockFunction<void(string check_point_name)> check;
  {
    InSequence s;

    EXPECT_CALL(mockObj, 1);
    EXPECT_CALL(check, "1");
    EXPECT_CALL(mockObj, 2);
    EXPECT_CALL(check, "2");
    EXPECT_CALL(check, "3");
    EXPECT_CALL(mockObj, 3);
  }
  
  foo(1);
  check.Call("1");

  foo(2);
  check.Call("2");

  foo(2);
  foo(2);

  check.Call("3");
  foo(3);
}

或使用 Mock::VerifyAndClearExpectations() 重置模拟，然后设置新的期望。

否则，某些答案中建议的对模拟和 EXPECT_CALL 的交错调用是未定义的行为：

重要提示：gMock 要求在调用模拟函数之前设置期望值，否则行为未定义。特别是，您不能将 EXPECT_CALL() 和对模拟函数的调用交错。

来自gmock for dummies，另见Interleaving EXPECT_CALL()s and calls to the mock functions

【讨论】：

【解决方案2】：

我会把它分成几个测试用例：

TEST(Foo, CalledOnFirstInvoation) {
  EXPECT_CALL(mockObj, 1); 
  foo(1);
}

TEST(Foo, CalledAgainWhenUsingDifferenArgument) {
  EXPECT_CALL(mockObj, 2); 
  foo(1);
  foo(2);
}

TEST(Foo, NotCalledWhenUsingSameArgument) {
  EXPECT_CALL(mockObj, 2); 
  foo(1);
  foo(2);
  foo(2);
  foo(2);
}

TEST(Foo, CalledAgainWhenUsingYetAnotherArgument) {
  EXPECT_CALL(mockObj, 3); 
  foo(1);
  foo(2);
  foo(2);
  foo(3);
}

【讨论】：

【解决方案3】：

你想要这样的东西吗？

EXPECT_CALL(mockObj, 1).Times(0);
EXPECT_CALL(mockObj, 2).Times(0); // #2
EXPECT_CALL(mockObj, 3); // #3

{
  EXPECT_CALL(mockObj, 1); // #1
  foo(1); // Matches #1
}

{
  EXPECT_CALL(mockObj, 2); // #4
  // Expect this call at the first invocation of foo(2)
  foo(2); // Matches #4
}

// These calls should not call my mockObj again, the above expectation is 
// intended for the first invocation of foo(2)
foo(2); // Matches #2
foo(2); // Matches #2

// And now, i expect it to be called
foo(3); // Matches #3

【讨论】：

谢谢！在自己的范围内拥有期望，就像一种魅力。
请检查@IanMartin 的答案。交错 EXPECT_CALL() 和调用模拟函数是未定义的行为。