There are currently a number of solutions for testing plugins - both in terms of unit testing and integration testing. This has resulted in a confusing situation where plugins can be tested in multiple different ways, and there are no clear instructions for a new plugin author in how to test their plugins.
The objective of this document is to assess all the current approaches, and their positives and negatives, and to provide a baseline for discussion about the various approaches. It will attempt to identify overlap and make proposals to reduce duplication and confusion. It will also attempt to document how to write integration tests for your plugin, depending on your objectives. It will not attempt to propose a single-replacement solution - as there are likely good reasons to have different types of testing, and a separation of different techniques into different plugins.
Definition: This is traditional unit testing - it takes no consideration for the fact that it is a Maven plugin, and tests the code itself.
maven-plugin-testing-harness: This library provides assistance for plugin testing by pre-constructing the Plexus components, providing stub objects for Maven functionality such as projects, and populating fields from an XML file that resembles the plugin configuration in the POM.
- standard JUnit testing: MOJOs written in Java can be tested using JUnit as standard Java objects (possibly using a mock framework to mock the Maven functionality such as projects). For non-Java MOJOs, a corresponding test framework may be used for that language but the same principles apply.
Definition: Integration testing for plugins is checking that a plugin works with the Maven framework libraries in a given situation, but does not do and end-to-end functional test of a Maven project.
Definition: Functional testing for plugins is running an entire Maven build that utilises a given plugin and verifies the output of the build process.