The ForTesting Methods Pattern

The ForTesting pattern involves creating public helper methods on a class to provide access to test-only functionality, and giving them a specific type of name (XForTesting or XForTest) to provide a signal at the call site that they are not intended for regular use.

Use this pattern when:

You have a widely-used object that you need to expose a small amount of test functionality on.

Don't use this pattern when:

• You have lots of different ForTesting methods: consider the TestApi pattern instead.
• Only a small set of test cases need access: consider the friend the tests pattern instead, to avoid polluting the public API.

Alternatives / See also:

• Friend the tests
• TestApi
• ForTesting in the style guide

How to use this pattern:

class Foo {
 public:
  // ... regular public API ...

  void DoStuffForTesting();
};

The ForTesting suffix indicates to code reviewers that the method should not be called in production code. There is a very similar antipattern in which the suffix is missing:

class Foo {
 public:
  // ... regular public API ...

  // Do not call! Only for testing!
  void DoStuff();
};