如何测试实现线程的代码

Question

我希望能够对以下内容进行 junit 测试：

private ExecutorService executor = Executors.newSingleThreadExecutor();
public void foo() {
  final EntityManagerFactory entityManagerFactory =
      entityManager.getEntityManagerFactory();
  executor.execute(new Runnable() {
    @Override
    public void run() {
      EntityManager entityManager =
          entityManagerFactory.createEntityManager();
      Session session = (Session) entityManager.getDelegate();
      try {
        SQLQuery query =
            session.createSQLQuery("SELECT * from foo_function()");
      } catch (HibernateException exception) {
        LOGGER.error("Exception: " + exception);
      }
    }
  });
}

我正在使用莫克托。我试图让它抛出异常，例如：

Mockito.doThrow(SQLException.class).when(mockSession).createSQLQuery(any(String.class));

它会在生成的线程中引发异常，但当我将其作为 Junit 测试运行时，它不会失败。

Answer 1

您需要

替换被测类中的 Executor 或 ExecutorService：

public class YourClass {
  private Executor executorService = Executor.newSingleThreadExecutor();
  public YourClass() {}
  /** package-visible for testing */
  YourClass(Executor executor) {
    /* ... */
  }
  public void foo() { /* ... */ }
}

。或者只是在你正在测试的方法中：

public class YourClass {
  public void foo() {
    foo(executorService);
  }
  /** package-visible for testing */
  void foo(Executor executor) {
    /* ... */
  }
}

之后，您可以使用手动或基于 Guava 的直接执行器，如这个 SO 问题及其答案：

@Test public void fooShouldHandlException() {
  // ...
  systemUnderTest.foo(new Executor() {
    @Override public void execute(Runnable r) { r.run(); }
  });
  // ...
}

或者将其替换为 Mockito 模拟，以在运行 Runnable 之前和之后进行测试：

@Test public void fooShouldHandlException() {
  Executor mockExecutor = Mockito.mock(Executor.class);
  ArgumentCaptor<Runnable> runnableCaptor =
      ArgumentCaptor.forClass(Runnable.class);
  systemUnderTest.foo(mockExecutor);
  // assert "before Runnable is run" state, if applicable
  verify(mockExecutor).execute(runnableCaptor.capture());
  runnableCaptor.getValue().run();
  // assert "after Runnable is run" state
}