Modern C++ Programming with Test-Driven Development

Mondo Extracto

We need to figure out where within the open function to call size. Our call could go near the end of open, immediately before the code sends a message to the descriptor object. But since size re-opens a file, we need to ensure that the new WAV file gets closed first.

Unfortunately, the structure of open presents quite a challenge. Code all the way up to the call to the descriptor is riddled with file reads and writes. Writing a test able to execute the entire function remains fairly challenging. (We could pass a real, vetted WAV file to open, but that would net us a slow and dependent test.)

Instead, we refactor open with the goal of deriving some functions that we might stub or mock. After about a dozen minutes of generally safe ...