Is it possible to define (pure virtual) test cases in a base class using googletest

Question

is it possible to define a base test-fixture with (abstract) test cases and derive classes from them?

There are two szenarios I'd like to support (Taken from Roy Overshores "The art of Unit Testing"):

Template test class pattern Define abstract test cases in the base test-fixture and thus force derived classes to implement them.
Abstract test driver class pattern Implement tests in the base class that all derived class inherit automatically

I cannot figure out how this works with googletest. If I have a base class

#pragma once class BaseClass : public ::testing::Test { }; TEST_F(BaseClass, T1) { }

and two derived classes (in different files)

#include "stdafx.h" #include "BaseClass.h" class DerivedClass1 : public BaseClass { };

and

#include "stdafx.h" #include "BaseClass.h" class DerivedClass2 : public BaseClass { };

I get the compiler error

virtual void __thiscall BaseClass_T1_Test::TestBody(void)" (?TestBody@BaseClass_T1_Test@@EAEXXZ) already defined in DerivedClass1.obj

Is it somehow possible to define concrete and pure virtual tests in a test base class?

I believe you can use typed tests to implement something similar to what these patterns are used for (or at least, get you close to what you need). See code.google.com/p/googletest/wiki/AdvancedGuide#Typed_Tests — RA.
– RA., Commented Jul 23, 2015 at 15:45

simon · Accepted Answer · 2015-07-23 13:45:43Z

Try move TEST_F(BaseClass, T1){} out of the BaseClass.h into its own .cpp file. The BaseClass.h is included into 2 .cpp files of DerivedClass1 and DerivedClass2, and during compilation the TEST_F will be expanded to a bunch of executable functions that would be included into both of these .cpp files. And that is why the linker is unhappy and complain about the duplication of symbol TestBody@BaseClass_T1_Test@@EAEXXZ).

Yeah, then it compiles. But the test is not executed for each derived class but only once. Because it is contained in a derived class by itself. I fear I'll have to do an ugly workaround like defining pure virtual methods in the BaseClass that I call from tests of the DerivedClasses
You have to provide more detail example about your code, or it would be difficult to help. Perhaps raise another question in SO.

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