Deprecate TestCase::createPartialMock()

[sebastianbergmann]

PHPUnit can automatically generate test stubs and mock objects (test doubles) based on interfaces and classes.

When it comes to doubling classes, there are limitations:

• final, private, and static methods cannot be doubled; they retain their original behavior except for static methods which will be replaced by a method throwing an exception
• Enumerations (enum) are final classes and therefore cannot be doubled
• readonly classes cannot be extended by classes that are not readonly and therefore cannot be doubled

Not only because of the limitations mentioned above, but also to improve your software design, PHPUnit's documentation recommends to favour the doubling of interfaces over the doubling of classes.

For quite a while, PHPUnit has offered the createStub() and createMock() methods for creating test stubs and mock objects with best practice defaults. Furthermore, alternatives such as createPartialMock() exist, but not all of them offer the same clear separation between test double and mock object. For instance, no method named createPartialStub() exists. Such an inconsistency can lead to confusion.

As its name suggests, the createPartialMock() method can be used to create a so-called partial mock object: a mock object where not all methods of the original class are replaced with an implementation that can be configured to return a specified value, for instance, or to expect an invocation.

Partial mocking is considered a code smell as it makes it not obvious to determine whether you are calling a method that has been doubled or whether you are calling an original method.

To promote better software design, improve the readability of test code, and to reduce complexity inside PHPUnit's test double functionality, TestCase::createPartialMock() will be deprecated and then removed:

• soft deprecation in PHPUnit 10.1 (add @deprecated annotation to the method declaration)
• deprecation in PHPUnit 11 (using the method will trigger a deprecation)
• removal in PHPUnit 12

[thetechdabbler]

@sebastianbergmann this is not yet soft deprecated. Is there any change of plans?

[sebastianbergmann]

createPartialMock() will not be deprecated in PHPUnit 11 and will not be removed in PHPUnit 12.

[rulatir]

How do I marry the superpowers of MockBuilder (specifying constructor args, disabling original constructor, etc.) with partial mocks? And not just anyhow, but in a way that - pinky promise - won't be deprecated next morning and removed after dinner?

[rela589n]

@sebastianbergmann , sorry, I didn't get the whole point,

createPartialMock() will not be deprecated in PHPUnit 11 and will not be removed in PHPUnit 12.

So is it deprecated/removed or not? Somewhat confusing to me