Modern C++ Programming with Test-Driven Development

8.12 A Brief Exploration in Seeking Faster Tests

Right now, we have exactly one slow test for the WAV Snippet Publisher codebase. We’ll strive to keep it that way. But if you need another file-based utility, you’d want to ensure you don’t add a second slow test. Once you allow them, slow tests add up quickly.

One possible solution is to separate out the portion of the functionality that deals only with the stream and test-drive it. For the ​size​ function, we could create an even smaller method.

TEST(StreamUtil_Size, AnswersNumberOfBytesWrittenToStream) {
   istringstream readFrom{"abcdefg"};

   CHECK_EQUAL(7, StreamUtil::size(readFrom));
}

std::streamsize size(std::istream& stream) {
 stream.seekg(0, ...