How to generate tests under GTest

One of the many features provided by GTest is the ability to generate test at runtime. One useful application of this is that you can execute data-driven testing by obtaining a list of test file names, then generating a test for each of them. It’s actually very simple to do this in GTest – they call these value-parameterized tests (see documentation). Here’s a snippet of code to demonstrate how little overhead is involved:

#include <gtest/gtest.h>

using namespace testing;

// placeholder - could be used for test setup/cleanup
class MyTest : public ::testing::TestWithParam<std::string>
{
};

TEST_P( MyTest, IntegrationTest )
{
    std::string test_file_name = GetParam();

    // open file and run the integration test
}

std::vector<std::string> test_file_names();

INSTANTIATE_TEST_CASE_P( MyLibraryName, MyTest, test::ValuesIn( test_file_names() ) );

On one hand, this approach isn’t really in the spirit of unit test – data-driven tests have a habit of quickly escalating to integration tests between libraries. However, such integration tests also have their place in a testing strategy, and this is a neat way to accomplish it with minimal overhead.