Custom Assertions

To create custom assertions between parameters passed to methods, you can use the CallTo(...).WillDoInstead() combo, and provide your own verification lambda:

Assuming the following class in production code:

class Person

{

public:

      int GetAverageChildAge(int child1, int child2) 

      { 

              return (child1 + child2) / 2;  

      }

 int CallPrivate(int var) 

      { 

              return SomePrivate(var);  

      }

private:

 int SomePrivate(int var){ return var; }

 int SomePrivate(string var){ return stoi(var); }

};

We'd like to create a custom assertion that GetAverageChildAge actually gets called with the parameters of the same parity, so let's create our verification lambda and use it:

TEST_F(Examples, CustomAssertion)

{

   // Arrange

   auto a = Isolator();  

   Person* personPtr = new Person();   

   a.CallTo(personPtr->GetAverageChildAge(A::Any(),A::Any()).WillDoInstead([](int param1, int param2) 

     { 

            // Assert

            int mod1 = param1 % 2;

            int mod2 = param2 % 2;

              ASSERT_EQ(mod1, mod2);

            return -1;

      });

   int child1 = 0;

   int child2 = 3;

   // Act

   // We should get an assert exception since the one arg is even and the other odd

   personPtr->GetAverageChildAge(child1, child2); 

}

For simpler custom assertions on parameters passed to methods, you can use the Conditional Checkers:

TEST_F(Examples, SimpleAssertion)

{

   // Arrange

   auto a = Isolator();  

   Person* personPtr = new Person();   

   a.CallTo(personPtr->GetAverageChildAge(A::Any(),A::Any()).WillBeIgnored();

   int child1 = 0;

   int child2 = 3;

   // Act

   personPtr->GetAverageChildAge(child1, child2); 

   // Assert

   a.CallTo(personPtr->GetAverageChildAge(A::Eq(0),A::Le(10)).VerifyWasCalled();

}

Note: In order to assert a specific overload was called with matching arguments, use the A::Matches<> API to specify the overload and the arguments predicate.

TEST_F(Examples, CustomAssertion)

{

   // Arrange

   auto a = Isolator();  

   Person* personPtr = new Person();   

   a.CallTo(personPtr->GetAverageChildAge(A::Any(),A::Any()).WillBeIgnored();

   int child1 = 0;

   int child2 = 3;

   // Act

   personPtr->GetAverageChildAge(child1, child2); 

   // Assert

   a.CallTo(personPtr->GetAverageChildAge(A::Eq(0),A::Matches([](int val){return  val==2 ;}))

   .VerifyWasCalled();

}

As in public methods, to assert a private overloaded method with matching arguments was called, use the A::Matches<> API:

TEST_F(Examples, CustomAssertion)

{

   // Arrange

   auto a = Isolator();  

   Person* personPtr = a.Fake.Instance<Person>(FakeOptions::CallOriginal);

   // Act

   personPtr->CallPrivate(10);

   // Assert

   a.CallToPrivate(A::Member(personPtr, SomePrivate),A::Matches([](int val){return  val==10;}))

   .VerifyWasCalled();

}