How do I assert my exception message with JUnit Test annotation?

Question

I have written a few JUnit tests with @Test annotation. If my test method throws a checked exception and if I want to assert the message along with the exception, is there a way to do so with JUnit @Test annotation? AFAIK, JUnit 4.7 doesn't provide this feature but does any future versions provide it? I know in .NET you can assert the message and the exception class. Looking for similar feature in the Java world.

This is what I want:

@Test (expected = RuntimeException.class, message = "Employee ID is null") public void shouldThrowRuntimeExceptionWhenEmployeeIDisNull() {} 

Answer 1

You could use the @Rule annotation with ExpectedException, like this:

@Rule public ExpectedException expectedEx = ExpectedException.none();  @Test public void shouldThrowRuntimeExceptionWhenEmployeeIDisNull() throws Exception {     expectedEx.expect(RuntimeException.class);     expectedEx.expectMessage("Employee ID is null");      // do something that should throw the exception...     System.out.println("=======Starting Exception process=======");     throw new NullPointerException("Employee ID is null"); } 

Note that the example in the ExpectedException docs is (currently) wrong - there's no public constructor, so you have to use ExpectedException.none().

Answer 2

In JUnit 4.13 you can do:

import static org.junit.Assert.assertEquals; import static org.junit.Assert.assertThrows;  ...  @Test void exceptionTesting() {   IllegalArgumentException exception = assertThrows(     IllegalArgumentException.class,      () -> { throw new IllegalArgumentException("a message"); }   );    assertEquals("a message", exception.getMessage()); } 

This also works in JUnit 5 but with different imports:

import static org.junit.jupiter.api.Assertions.assertEquals; import static org.junit.jupiter.api.Assertions.assertThrows;  ...