Testing Best Practices Java

Intro:

• These are our best practices around unit testing
• They should be followed when writing tests, but exceptions can be made

Best Practices:

• A test should include //given, //when, //then comments, so it is easy to see what is tested

@Test
public void shouldCheckFoo() {
  // given
  <test setup>
  
  // when
  <trigger logic under test>
  
  // then
  <fetch result>  
  <assert result>
}

• Naming Conventions
  • Camel case
  • JUnit 4 tests are prefixed with "should", e.g. shouldCheckComponentAvailability()
• A test should not test multiple things, i.e. there can be only one when part
• The when part only triggers the code under test; Any lookup for results goes into the then part
• Query tests should assert the results, not only the count of results (exception: the query returns all results)
  • Relevant for all types of query tests (e.g., also for authorization query tests, etc.)
  • Count-based query tests are error-prone since they don't verify that the correct data is retrieved
  • The following AssertJ assertion verifies the right count as well as the correct data:

    assertThat(query.list())
        .extracting("taskId")
        .containsExactlyInAnyOrder("taskIdOne", "taskIdTwo");

• If you need to scroll down to see the whole test, consider to break it down
• A test should always have at least one assertion
• Use fluent AssertJ assertions
• If possible, use JUnit 4 conventions (e.g. test rule, ExpectedException rule)
• Write blackbox tests based on public API
  • Avoid writing tests that rely on internal API (e.g. for preparing a certain state)
  • Avoid testing internal API
• Preferred Annotation order:

@Ignore
@Test
@Deployment(resources = {"testProcess.bpmn"})

• For common test setup and tear down (e.g. services, deployments), use @Before and @After methods
• Use @RequiredHistoryLevel on method or class level, if a test requires a certain history level