Monday, June 23, 2008

Static imports for Hamcrest and Theories

The Hamcrest and Theories features of JUnit 4.4 rely on a number of static imports.

Code completion for static imports is tricky. For example, if I want to use the both Matcher, I firstly have to remember that it is in the JUnitMatchers class, type in JUnitMatchers (or JUM), then ctrl-space to get code completion to fill in the import, then type in .both and remove the JUnitMatchers.

As mentioned in the JUnit 4.4 release notes, Eclipse provides a Favorites preference that automatically includes your favourite classes in code assist. For example, after setting up JUnitMatchers in your Favorites, you can type in both, ctrl-space, and Eclipse will import JUnitMatchers.both.

Adding the static types shown here to your Eclipse Favorites will make your JUnit 4.4 journey a lot smoother.

PS. The both Matcher allows you to create assertions such as:
assertThat(e.getMessage(), both(startsWith("Invalid environment")).and(containsString(environmentName));
as opposed to the more common:
assertThat(e.getMessage(), allOf(startsWith("Invalid environment"), containsString(environmentName)));
It's debatable which is cleaner. The top statement reads closer to the English language, but is longer, more complex to construct and can't have additional matchers added in the same way that allOf can.

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