Check if element equality for different container types in Google Test

March 28, 2023

I want to check if the elements in two containers of different types are the same. However, when I use the ContainerEq matcher of the GoogleTest library it gives me an error that it can not initialize the vector from the array:

TEST(TestExample, Example) {
    std::array<int, 4> ar = {1,2,3,4};
    std::vector<int> v(ar.begin(), ar.end());

    EXPECT_THAT(ar, ::testing::ContainerEq(v));
}

Error message:

error: invalid initialization of reference of type 'testing::internal::ContainerEqMatcher<std::vector<int> >::StlContainerReference' {aka 'const std::vector<int>&'} from expression of type 'const type' {aka 'const std::array<int, 4>'}

What options do I have to check for equality in different containers except for switching to EXPECT_TRUE and using std::equal?

>Solution :

You can compare elements of different containers using ::testing::ElementsAreArray(v):

TEST(TestExample, Example) {
    std::array<int, 4> ar = {1,2,3,4};
    std::vector<int> v(ar.begin(), ar.end());

    EXPECT_THAT(ar, ::testing::ElementsAreArray(v));
}