Mocking free function

Question

I am stuck in a problem and can\'t seem to find the solution.

I am using VS2005 SP1 for compiling the code.

I have a global function:

A* foo(         


        

Answer 1

There are 2 options:

If you insist on using gmock, there's an "extension" for global mocking from apriorit: https://github.com/apriorit/gmock-global

It's rather limited, though - or at least I couldn't figure out in 5 minutes how to have side effects on a mocked call.

If you're willing to switch from gmock, then hippomocks has a very neat way of doing what you want.

Here's an example for mocking fopen, fclose and fgets for testing a member function which reads from a file using cstdio (streams are very inefficient):

TEST_CASE("Multi entry") {
    std::vector files{"Hello.mp3", "World.mp3"};
    size_t entry_idx = 0;
    MockRepository mocks;
    mocks.OnCallFunc(fopen).Return(reinterpret_cast(1));
    mocks.OnCallFunc(fgets).Do(
        [&](char * buf, int n, FILE * f)->char *{ 
            if (entry_idx < files.size())
            {
                strcpy(buf, files[entry_idx++].c_str());
                return buf;
            }
            else
                return 0;
            }
        );
    mocks.OnCallFunc(fclose).Return(0);

    FileExplorer file_explorer;
    for (const auto &entry: files)
        REQUIRE_THAT(file_explorer.next_file_name(), Equals(entry.c_str()));
    REQUIRE_THAT(file_explorer.next_file_name(), Equals(""));
}

Where the function under test looks like this:

string FileExplorer::next_file_name() {
    char entry[255];
    if (fgets((char *)entry, 255, _sorted_entries_in_dir) == NULL)
        return string();
    _current_idx++;
    if (_current_idx == _line_offsets.size())
        _line_offsets.push_back(static_cast(char_traits::length(entry)) + _line_offsets.back());
    return string(entry);
} 

I'm using catch2 as the testing framework here, but I think hippomocks would work with Google's Testing framework as well (I recommend catch2, by the way, really easy to work with).