gtest - parametrized tests limit, compilation error

Question

When I instantiate more than 50 parametrized tests I get the following error:

main.cpp:31: error: expected class name
main.cpp:49: error: no matching function for call to 'Values'
gtest-param-test.h:1411: expanded from macro 'INSTANTIATE_TEST_CASE_P'
gtest-param-test.h:342: candidate function template not viable: requires single argument 'v1', but 51 arguments were provided
gtest-param-test.h:347: candidate function template not viable: requires 2 arguments, but 51 were provided
gtest-param-test.h:352: candidate function template not viable: requires 3 arguments, but 51 were provided
gtest-param-test.h:357: candidate function template not viable: requires 4 arguments, but 51 were provided
//and so on

Here is an example simplified code which I use:

template <typename param>
class MyFixtureWithParam: public ::testing::Test, public ::testing::WithParamInterface<param>
{
};

using MyPair = std::pair<std::string, std::string>;
using MyTests = MyFixtureWithParam<MyPair>;

TEST_P(MyTests, Params)
{
}

INSTANTIATE_TEST_CASE_P(Params, MyTests, ::testing::Values(std::make_pair("aaa", "bbb"),
                                                           std::make_pair("aaa", "bbb")));

More than 50 make_pair generate that error. How to fix that ?

Answer 1

I think the reason of this problem is a non-variadic template function in Gtest library

https://github.com/google/googletest/blob/main/googletest/include/gtest/gtest-param-test.h

max amount of values

If u wanna fix this problem ud rather use stl containers

auto GetData(){
   std::vector< std::tuple < std::string, std::string > > vec;
   for(int i = 0; i < 5; i++ ){
      vec.push_back(std::make_tuple("a", "b" ));
   }
   return ::testing::ValuesIn(vec);
}

using Mytype = std::vector< std::tuple < std::string, std::string > >;

TEST_P(YourClassName, YourTestName){
   std::string a,b;
   std::tie(a,b) = GetParam();
   
   ASSERT ...
}

INSTANTIATE_TEST_CASE_P(YourClassName, YourTestName, GetData());