Comments on: Integrating Mocking With C++ Default Parameters

By: Jonathan O'Connor

Jonathan O'Connor — Tue, 28 Aug 2018 09:56:00 +0000

Very interesting idea. I have seen a C++ mocking framework that replaces the implementation of functions with Python code at runtime. It relies on the linker DWARF(?) data to get the addresses.

For more information look at the last talk here: https://www.meetup.com/cppdug/events/251408066/

By: Jeff Andrews

Jeff Andrews — Wed, 22 Aug 2018 00:52:00 +0000

In reply to Dirk Reum. My sentiments exactly

By: Dirk Reum

Dirk Reum — Tue, 21 Aug 2018 15:47:00 +0000

One option not yet mentioned: Remember you have another “seam” in your code, that is the linker. You can keep your code above exactly as is but link your tests against a dummy logging library that does nothing, while the production code would link against the real logger.

By: Abel Suranyi

Abel Suranyi — Tue, 21 Aug 2018 09:20:00 +0000

Hi,

It’s a good article. I have only one thing to add which can help to make the code more simple. In tests it is allowed to declare the function signature with different default parameters.

In this case it will be something similar:

int f(int x, int y, const LoggerSeam& logger = LoggerMock());

(I didn’t try it, so they possibly will collide during lookup if they are present in the same scope, but declared in different namespace level/scope it must work.)

By: Sergio Adán

Sergio Adán — Tue, 21 Aug 2018 08:01:00 +0000

You can provide logging facility by using a static class or function that must be initialized before using it. Then in production you initialize the real logging class but in testing mock class should be initialized.

You can see an example in the following link: https://wandbox.org/permlink/IeZ9wZU60lOi88kW

Now, as you can see f function does not need to know if it is in a real context or in a testing one and it wont be a responsibility of the caller to know what logging class should be use.

Of course the most appropriate solution depends on the nature of the project.

Regards