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With Magnolia 4.5 we switched to JUnit 4. As it is fully backwards compatible, this does not enforce you to write your tests in the new v4-style (e.g. use @Test, @Before etc.).

Junit 4 style

  • all new test will be written in JUnit 4 style
  • existing tests have been converted SCRUM-317

Behavior Driven Development (BDD) Style

  • in order to increase readability, we use the bdd-like style: // GIVEN, // WHEN, // THEN
  • test-method names should describe what they're doing (-> proper sentence)
  • as in all our java code we use camelCaseStyle names for test and their methods
pure Mockito
    // GIVEN
    <all code required to set up the situation goes here or in dedicated setUp (@Before) methods>

    // WHEN
    < execute whatever method you actually want to test>

    // THEN
    <verify your expectations>

More on testing Magnolia with Mockito can be found here.

Granularity

If you're testing multiple scenarios (having multiple // WHEN - // THEN section is an indicator for that), put each of them into a dedicated test method:

  • if an early scenario fails, the others will still be executed: you'll always exactly know what is broken and what not
  • as you have explicit test methods, you can name them explicitly: helps a lot to understand - not only when one of them is failing
    • e.g. if you wanted to test a String-To-Integer-Parser
      • canParsePositiveInteger
      • canParseNegativeInteger
      • throwsParseExceptionOnInvalidChars

Matchers

An example will be more explicit than a verbose explanation:

        assertThat(filterNode, hasContent("clientCallbacks", "mgnl:content"));

        // you can even apply multiple conditions in one go:
        assertThat(filterNode, allOf(
                not(hasContent("clientCallback")),
                hasContent("clientCallbacks", "mgnl:content")
        ));

... and a sample output when the test fails:

java.lang.AssertionError: 
Expected: a child node named 'clientCallbacks' of type 'mgnl:content'
     but: config:/server/filters/dummySecurityFilter[mgnl:content] has a child node named 'clientCallbacks' but it is not of type 'mgnl:content'

Much more expressive that a series of calls to the content/jcr apis and regular assert methods right ?
This is done via Hamcrest matchers.

Make sure you have the following imports

import static info.magnolia.test.hamcrest.ContentMatchers.*;
import static info.magnolia.test.hamcrest.UtilMatchers.*;
import static org.hamcrest.MatcherAssert.assertThat;
import static org.hamcrest.CoreMatchers.*;
import static org.junit.Assert.*;

org.junit.Assert also has an assertThat() method, which works just as well, but Hamcrest's describe the problems much better, which is why the hamcrest imports need to be above junit's (which should be fine alphabetically).
See https://github.com/KentBeck/junit/issues/36 for an update on this.

Have a look at the existing matchers in Hamcrest, as well as ours in the info.magnolia.test.hamcrest package
... then use Google for more examples.

Tests expecting Exceptions

Various techniques are possible (see Greg's examples at git.magnolia-cms.com:user/gjoseph/kt/matchers.git (ExceptionMatchingTest), but we favor this most readable and controllable one:

/**
 * @see info.magnolia.test.hamcrest.ExecutionMatcherTest for more examples !
 */
@Test
public void executionMatchers() {
    assertThat(new Execution() {
        public void evaluate() throws Exception {
            divide(4, 0);
        }
    }, throwsAnException(instanceOf(ArithmeticException.class).withMessage(containsString("zero"))));
}
 
/**
 * Use Java8's lambdas for readability/conciseness.
 */
@Test
public void executionMatchersWithJava8() {
    assertThat(() -> divide(4, 0), throwsAnException(instanceOf(ArithmeticException.class).withMessage(containsString("zero"))));

}

Clean up global state

It's important that your test dont leave things behind and risk affecting other tests.

  • Always do Components.setProvider(null) if you set a ComponentProvider
  • Always call MgnlContext.setInstance(null) if you set a Context
  • Always reset any properties you set

Always add this in you test (it gets executed after every test method):

    @After
    public void tearDown() throws Exception {
        ComponentsTestUtil.clear();
        SystemProperty.clear();
        MgnlContext.setInstance(null);
        Components.setProvider(null);
    }

Temporarily disable Test

For the rare case that you have to temporarily disable tests, always use the @Ignore annotation - don't comment out whole test methods because

  • this will preserve the imports
  • will be considered when refactoring
  • it's easily possible to search for ignored tests and reanimate them (not obvious to find commented out tests)
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