November 28, 2009

Unit and Integration Testing with Maven, Part 1

Test Types

In my last post, I talked about integration testing with Maven's Cargo plugin and JBoss Application Server. Now let's see how integration testing fits into an overall testing strategy with Maven.

When thinking about tests and testing strategies, there is one important thing to keep in mind: integration tests are not unit tests (even though JUnit may be used to write integration tests). For the sake of completeness, let's pin down the main characteristics of both:

Unit Tests:

  • are testing a small piece of code in isolation
  • are independant from other tests
  • are usually written by software developers
  • have to be very fast because they are run quite often

In contrast, Integration Tests:

  • individual software modules are combined and tested as a group
  • are usually much slower than unit tests because a context has to be established (Spring, database, web server etc.)
  • normally are run after unit testing
  • may be created by QA team using tools, but also by developers using JUnit test cases (which still does not turn them into unit tests)

Testing with Maven

As you know, Maven Build Lifecycle provides phases both for testing and integration testing. Related phases are:

...
generate-test-sources
generate-test-resources
process-test-resources
test-compile
process-test-classes
test
...
pre-integration-test
integration-test
post-integration-test
...

Unfortunately, Maven does not support separate source directories for both test types. This is really complicating things (as we'll see in a minute). There have been some discussions on how to fix that, but I don't think it made it into Maven 3 (not quite sure, though).

Hence, what we need to have is this:

  • Both unit and integration tests have to be compiled by javac.
  • Nevertheless, they should be clearly separated from each other by a path or file name pattern.
  • Unit tests have to be run in test lifecycle phase, and the build should stop if they do not succeed.
  • Integration tests should be run in integration-test phase, and at least the post-integration-test phase has to be run independantly of test result (to be able to shutdown a running container, close database connections etc.).

The next part of this small series will show how these requirements can be met with Maven and what has to be configured, so please stand by...

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