Expect exception when using JUnit Theory

Question

In JUnit 4 you can declare expected exception using @Test(expected = SomeException.class) annotation. However, when testing is done using Theories, @Theory annotation does not have expected property.

What is the best way to declare expected exception when testing Theories?

Answer 1

I prefer using ExpectedException rule :

import org.junit.rules.ExpectedException;

<...>

@Rule
public ExpectedException thrown = ExpectedException.none();

@Theory
public void throwExceptionIfArgumentIsIllegal(Type type) throws Exception {
    assumeThat(type, equalTo(ILLEGAL));
    thrown.expect(IllegalArgumentException.class);
    //perform actions
}

Answer 2

Also you can use a normal assert . You can use it on older versions of JUnit (before 4.9).

@Test
public void exceptionShouldIncludeAClearMessage() throws InvalidYearException {
    try {
        taxCalculator.calculateIncomeTax(50000, 2100);
        fail("calculateIncomeTax() should have thrown an exception.");
    } catch (InvalidYearException expected) {
        assertEquals(expected.getMessage(),
                     "No tax calculations available yet for the year 2100");
    }
}