junit4.md

JUnit 4 - Tips & Tricks

How to specify a "Runner"

With the @RunWith(MyRunner.class) annotation on the test class:

Common Runners :

• Spring : @RunWith(SpringJUnit4ClassRunner.class)
• Spring-Boot : @RunWith(SpringRunner.class) Spring Boot features - Testing
• Mockito : @RunWith(MockitoJUnitRunner.class) http://site.mockito.org/
• JMockit : @RunWith(JMockit.class) http://jmockit.github.io/
• PowerMock : @RunWith(PowerMockRunner.class) http://powermock.github.io/

How to sort methods

With the @FixMethodOrder annotation on the test class:

@RunWith(MonRunnerHabituel.class)
@FixMethodOrder(MethodSorters.NAME_ASCENDING)
public class SomeTest {
  @Test
  public void test_1_first() {
    System.out.println("first executed test");
  }
  @Test
  public void test_2_second() {
    System.out.println("second executed test");
  }
  @Test
  public void test_3_third() {
    System.out.println("third executed test");
  }
}

⚠️ Alphabetic order (NAME_ASCENDING)

How to specify a timeout

For example, for a test that performs a remote service call (to be avoided) or a local HTTP server mock, it is advisable to set a delay. So that JUnit can stop the test if it lasts too long.

Simply with @Test :

  @Test(timeout = 10_000)
  public void should_test() {
    callHttpService();
  }

ℹ️ Timeout in milliseconds.

⚠️ JUnit JavaDoc : Test methods with a timeout parameter are run in a thread other than the thread which runs the fixture's @Before and @After methods.

Deal with exceptions

First way (poor)

Simply with @Test :

  @Test(expected = TechnicalException.class)
  public void should_test() {
    callService();
  }

Second way (better)

With @Rule :

On the test class:

  @Rule
  public final ExpectedException expectedEx = ExpectedException.none();

In the test method:

  @Test
  public void should_test() {
    expectedEx.expect(TechnicalException.class);
    expectedEx.expectMessage("my expected message");

    callService();
  }

Validate an exception cause:

  @Test
  public void should_test() {
    expectedEx.expectCause(IsInstanceOf.instanceOf(IllegalArgumentException.class));
    expectedEx.expectMessage("my expected message");

    callService();
  }

How to ignore tests

First way (very poor)

Simply with @Ignore :

  @Test
  @Ignore
  public void should_test() {
    callService();
  }

Second way (poor)

With the Maven Surefire plugin:

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-surefire-plugin</artifactId>
  <configuration>
    <excludes>
      <exclude>**/IgnoredTest1*</exclude>
      <exclude>**/IgnoredTest2*</exclude>
    </excludes>
  </configuration>
</plugin>

Third way (better)

With @Categoryannotation.

First step Define an annotation like this one:

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface MyLocalTest {

}

Second step Configure the Maven Surefire plugin:

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-surefire-plugin</artifactId>
  <configuration>
    <groups></groups>
    <excludedGroups>com.myorg.category.MyLocalTest</excludedGroups>
  </configuration>
</plugin>

Third step Add the @Category annotation with your own annotation on the categorized tests:

  @Test
  @Category(MyLocalTest.class)
  public void should_be_ignored_by_maven() {
    callService();
  }