How to test extensions

Question

The JUnit 5 API has several extension points.

For instance:

• AfterEachCallback
• AfterAllCallback
• AfterTestExecutionCallback
• BeforeAllCallback
• BeforeEachCallback
• BeforeTestExecutionCallback
• ExecutionCondition
• ParameterResolver
• TestExecutionExceptionHandler
• TestInstancePostProcessor
• TestTemplateInvocationContextProvider

Almost all of these extensions are in the form ExtensionContext, which provides access to the test class , test method , test instance , the ability to publish a report recording , save the values and other features. Many of them work directly on class instances.

Most implementations are likely to use some combination of reflection usingReflectionSupport and usingAnnotationSupport , which are static methods, making it difficult to falsify them.

, , ExecutionCondition , BeforeEachCallback, AfterEachCallback - ?

, ExtensionContext, .

JUnit ExecutionEventRecorder, JupiterTestEngine ( @API(status=INTERNAL)) , .

- public JupiterTestEngine.

---

:

• An ExecutionCondition, . TestInfo @BeforeEach @AfterEach, . " ExtensionContext ".

  @Target(ElementType.METHOD)
  @Retention(RetentionPolicy.RUNTIME)
  @ExtendWith(SystemPropertyCondition.class)
  public @interface SystemProperty {
    String key();
    String value();
  }
  
  public class SystemPropertyCondition implements ExecutionCondition {
    @Override
    public ConditionEvaluationResult evaluateExecutionCondition(final ExtensionContext context) {
      return context.getTestMethod()
          .flatMap(element -> AnnotationSupport.findAnnotation(element, SystemProperty.class))
          .map(systemProperty -> {
            if (systemProperty.value().equals(System.getProperty(systemProperty.key()))) {
              return ConditionEvaluationResult.enabled("Property is available");
            } else {
              return ConditionEvaluationResult.disabled("Property not equal");
            }
          })
          .orElseGet(() -> ConditionEvaluationResult.enabled("No annotations"));
    }
  }
  

• An ExecutionCondition, . ? , ? , / ExtensionContext.Store, - (, BeforeEachCallback, , . , BeforeEachCallback ExecutionCondition, 1. " ", , ExtensionContext .

  @ExtendWith(RunOnDayCondition.class)
  public @interface RunOnDay {
    DayOfWeek[] value();
  }
  
  final class RunOnDayCondition implements ExecutionCondition {
  
    private static final ConditionEvaluationResult DEFAULT = disabled(
        RunOnDay.class + " is not present"
    );
  
    @Override
    public ConditionEvaluationResult evaluateExecutionCondition(final ExtensionContext context) {
      return context.getElement()
          .flatMap(annotatedElement -> findAnnotation(annotatedElement, RunOnDay.class))
          .map(RunOnDay::value)
          .map(RunOnDayCondition::evaluateIfRunningOnDay)
          .orElse(DEFAULT);
    }
  
    private static ConditionEvaluationResult evaluateIfRunningOnDay(final DayOfWeek[] days) {
      // TODO: How would you inject a test clock?
      final DayOfWeek currentDay = LocalDate.now().getDayOfWeek();
      final boolean runningInday = Stream.of(days).anyMatch(currentDay::equals);
  
      if (runningInday) {
        return enabled("Current day is " + currentDay + ", in the specified days of " + Arrays.toString(days));
      } else {
        return disabled("Current day is " + currentDay + ", not in the specified days of " + Arrays.toString(days));
      }
    }
  }
  

• , , , . ParameterResolver, BeforeEachCallback, AfterEachCallback ExtensionContext.Store. , .

?

, API "" mocks?

Answer 1

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