Unit testing of private methods

c++ unit-testing private-methods
Mumbles picture Mumbles · Sep 9, 2010 · Viewed 74.8k times · Source

I am in the process of writing some unit tests. In particular I want to test some private methods.

So far the I have come up with using.

#define private public

But I am not happy with this as it will destroy all encapsulation from the point of view of the unit test.

What methods do you use to unit-test private methods.

Answer

Anthony Williams picture Anthony Williams · Sep 9, 2010

Rather than the nasty #define hack you mention in the question, a cleaner mechanism is to make the test a friend of the class under test. This allows the test code (and just the test code) access to the privates, whilst protecting them from everything else.

However, it is preferable to test through the public interface. If your class X has a lot of code in the private member functions then it might be worth extracting a new class Y which is used by the implementation of class X. This new class Y can then be tested through its public interface, without exposing its use to the clients of class X.

Related questions

How to do unit testing on private members (and methods) of C++ classes

I am very new to unit testing and I am a little confused. I am trying to do unit testing (using the Boost unit testing framework) on a C++ class called VariableImpl. Here are the details. class Variable { public: void …

Read More
Comparison of C++ unit test frameworks

I know there are already a few questions regarding recommendations for C++ unit test frameworks, but all the answers did not help as they just recommend one of the frameworks but do not provide any information about a (feature) comparison. …

Read More
How do I make Visual Studio pause after executing a console application in debug mode?

I have a collection of Boost unit tests I want to run as a console application. When I'm working on the project and I run the tests I would like to be able to debug the tests, and I would …

Read More