Isolator++ can change the behavior of methods very easily, without changing the original implementation. When you change the behavior of an instance or a static method, you can do that in different fashions.
We have a Person class. It has a method called IsFromLA we’d like to test:
bool Person::IsLivingInLA()
{
Address* address = Address::GetAddress();
if (strcmp (address->GetCity(),"Los Angeles")==0)
{
return true;
}
else
return false;
}
Person is dependent on the Address class:
#define CLASS_API __declspec(dllexport)
class CLASS_API Address
{
private:
char* city;
public:
void SetCity(char* newCity) {city = newCity;}
char* GetCity() {return city;}
static Address* GetAddress()
{
throw ("Not implemented yet!");
}
}
As you can see the static GetAddress method throws an exception, and therefore prevents us from testing the IsLivingInLA method. Let’s write a test for the case the person lives in LA:
1 TEST_F(PersonTests, IsLivingInLA_AddressIsLA_ReturnsTrue)
2 {
3 Person person;
4 Address laAddress;
5 laAddress.SetCity( "Los Angeles");
6
7 FAKE_STATICS<Address>();
8 WHEN_CALLED(Address::GetAddress()).ReturnPtr(&laAddress);
9
10 ASSERT_TRUE(person.IsLivingInLA());
11 ISOLATOR_CLEANUP();
12 }
- Line 4-5: We create the replacement LA Address object first.
- Line 7: We then declare we’re faking the static methods of the Address type using FAKE_STATICS.
- Line 8: We’re declaring that when the GetAddress method gets called, it will return the LA Address instead of throwing the exception.
- Line 11: Cleanup all faking definitions, so they won’t leak into the next test.
Let’s look at the other case, where the person is not from LA:
1 TEST_F(PersonTests, IsLivingInLA_AddressIsNotFromLA_ReturnsFalse)
2 {
3 Person person;
4 Address nyAddress;
5 nyAddress.SetCity( "New York City");
6
7 FAKE_STATICS<Address>();
8 WHEN_CALLED(Address::GetAddress()).ReturnPtr(&nyAddress);
9
10 ASSERT_FALSE(person.IsLivingInLA());
11 ISOLATOR_CLEANUP();
12 }
In this case we create an Address object that is initialized differently, and we can test that for that scenario, we get back FALSE.
Stay tuned for more how-to’s. Which one would you like to see next?
