How can I test asynchronous code in Java?

How can I test asynchronous code in Java?

You can use frameworks like JUnit along with CompletableFuture or libraries like Mockito to test asynchronous code.

Can you give me an example using JUnit?

Sure! You can use the CompletableFuture and assert its result in a JUnit test like this:

@Test
public void testAsyncMethod() throws Exception {
    CompletableFuture<String> future = asyncMethod();
    String result = future.get();
    assertEquals("Expected Result", result);
}

What if the asynchronous method throws an exception?

You can handle exceptions by using CompletableFuture.exceptionally() or by asserting that the exception is thrown in your test.

Can I use Mockito to mock asynchronous calls?

Yes, Mockito can be used to mock asynchronous calls. You can use when(...).thenReturn(...) to return a CompletableFuture.