Writing unit tests can be hard and sometimes good design has to be sacrificed for the sole purpose of testability. Often testability corresponds to good design, but this is not always the case. For example final classes and methods cannot be used, private methods sometimes need to be protected or unnecessarily moved to a collaborator, static methods should be avoided completely and so on simply because of the limitations of existing frameworks.

PowerMock is a framework that extend other mock libraries such as EasyMock with more powerful capabilities. PowerMock uses a custom classloader and bytecode manipulation to enable mocking of static methods, constructors, final classes and methods, private methods, removal of static initializers and more. By using a custom classloader no changes need to be done to the IDE or continuous integration servers which simplifies adoption. Developers familiar with EasyMock will find PowerMock easy to use, since the entire expectation API is the same, both for static methods and constructors. PowerMock extends the EasyMock API with a small number of methods and annotations to enable the extra features. From version 1.1 PowerMock also has basic support for Mockito.

When writing unit tests it is often useful to bypass encapsulation and therefore PowerMock includes several features that simplifies reflection specifically useful for testing. This allows easy access to internal state, but also simplifies partial and private mocking.

News

• 2009-10-28: Johan blogs about the new Mockito support in PowerMock 1.3 at the Jayway team blog.
• 2009-10-28: PowerMock 1.3.1 has been released. This release fixes a few bugs that were encountered in the 1.3 release. See change log for details.
• 2009-10-06: PowerMock 1.3 has now been released with improved Mockito support and many other changes. Please refer to the release notes for more information. We're working to get the documentation up to date.
• 2009-06-15: Basic documentation for Mockito is now online (thanks to Jeff Szeto for providing this).
• 2009-06-12: Documented the test listener support.
• 2009-05-17: Johan blogs on how PowerMock is able to mock static methods in system classes at the Jayway team blog.

Documentation

• Getting started
• Motivation
• Javadoc
• Javadoc EasyMock API extension
• Javadoc Mockito API extension
• Javadoc Whitebox class

Usage

EasyMock extension

1. Mocking static methods
2. Mocking final methods or classes
3. Mocking private methods
4. Mock construction of new objects
5. Partial Mocking
6. Replay and verify all
7. Mock Policies
8. Mock static methods in system classes
9. Test listeners
10. More to come...

Mockito extension

1. Mockito 1.8 usage (requires PowerMock 1.3)
2. Mockito 1.7 usage (requires PowerMock 1.2.5)

Common

1. Bypass encapsulation
2. Suppress unwanted behavior
3. Test listeners
4. Mock Policies (examples are made with EasyMock extension API)

Tutorial

1. PowerMock tutorial

FAQ

• FAQ

For questions and support please join our Google Group.