Faking members and local variables

When a class contains non-pointer object members created internally, you can use the Fake.All API to control the behavior of these objects. This approach allows you to fake specific behaviors of the object's methods without faking the entire class.

Here’s the Person class where the Address object is a direct member (not a pointer):

class Person

{

private:

   Address address;

public:

   Person() {} 

   char* GetCity() {return address.GetCity();}

}

To fake the behavior of the address object, follow these steps:

1. Use Fake.All<Address>() to create a fake handle for all future instances of the Address class.

2. Set the desired behavior using CallTo.

3. Create an instance of the Person class. The address member will automatically use the fake.

In our example we create a fake Address handle, and we can set behavior for all current Address object.

The test looks like this:

TEST_F(PersonTests, FakeAddress)

{

   // Arrange

   auto a = Isolator();  

   // Fake all Persons, we get a handle 

   Address* addressHandle = a.Fake.All<Address>();

   a.CallTo(fakeAddress->GetCity()).WillReturn("NYC");

   // Create a new person, the Address will be a fake

   Person person;

   // Act

   auto result = person.GetCity();  

   // Assert

   ASSERT_EQ("NYC", result);

}

Similarly, if your method under-test creates a local variable during its run, use Fake.All API to set its behavior:

int Person::DoSomething()

{

   SomeClass someClass;

   return someClass.DoSomethingElse();

}

And the test set up might look like this:

TEST_F(PersonTests, FakeAddress)

{

   // Arrange

   auto a = Isolator();  

   // Fake all Persons, but call the real method, we get a handle 

   auto someClassHandle = a.Fake.All<SomeClass>();

   a.CallTo(SomeClass->DoSomethingElse()).WillReturn(1);

   // Act

   auto result = person.DoSomething();  

   // Assert

   ASSERT_EQ(1, result);

}