JUnit 5: How to assert an exception is thrown?

You can use assertThrows(), which allows you to test multiple exceptions within the same test. With support for lambdas in Java 8, this is the canonical way to test for exceptions in JUnit.

Per the JUnit docs:

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

@Test
void exceptionTesting() {
    MyException thrown = assertThrows(
           MyException.class,
           () -> myObject.doThing(),
           "Expected doThing() to throw, but it didn't"
    );

    assertTrue(thrown.getMessage().contains("Stuff"));
}