des4maisons des4maisons - 29 days ago 22
C++ Question

Google Test: Parameterized tests which use an existing test fixture class?

I have a test fixture class which is currently used by many tests.

#include <gtest/gtest.h>
class MyFixtureTest : public ::testing::Test {
void SetUp() { ... }
};


I would like to create a parameterized test which also uses all that MyFixtureTest has to offer, without needing to change all my existing tests.

How do I do that?

I have found similar discussions on the web, but have not fully understood their answers.

Answer

The problem is that for regular tests your fixture has to be derived from testing::Test and for parameterized tests, it has to be derived from testing::TestWithParam<>.

In order to accommodate that, you'll have to modify your fixture class in order to work with your parameter type

template <class T> class MyFixtureBase : public T {
  void SetUp() { ... };
  // Put the rest of your original MyFixtureTest here.
};

// This will work with your non-parameterized tests.
class MyFixtureTest : public MyFixtureBase<testing::Test> {};

// This will be the fixture for all your parameterized tests.
// Just substitute the actual type of your parameters for MyParameterType.
class MyParamFixtureTest : public MyFixtureBase<
    testing::TestWithParam<MyParameterType> > {};

This way you can keep all your existing tests intact while creating parameterized tests using

TEST_P(MyParamFixtureTest, MyTestName) { ... }
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