How do I test exceptions in a parameterized test?

Question

In JUnit4 you can write parameterized unit tests by providing parameters collection in one method, which will be passed to the constructor of the test and testing in another method. If I have a parameter for which I expect an exception to be thrown, how do I specify that?

Answer 1

this is how i use junit parameterized test with expected exceptions:

@RunWith(Parameterized.class)
public class CalcDivTest {

@Parameter(0)
public int num1;
@Parameter(1)
public int num2;

@Parameter(2)
public int expectedResult;

@Parameter(3)
public Class<? extends Exception> expectedException;
@Parameter(4)
public String expectedExceptionMsg;

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

@Parameters
public static Iterable<Object[]> data() {
    return Arrays.asList(new Object[][] {
        // calculation scenarios:
        { 120, 10, 12, null, null }, // simple div  
        { 120, 0, -1, ArithmeticException.class, "/ by zero" }, // div by zero          
    });

}

@Test
public void testDiv() throws CCalculationException {

    //setup expected exception
    if (expectedException != null) {
        thrown.expect(expectedException);
        thrown.expectMessage(expectedExceptionMsg);
    }

    assertEquals("calculation result is not as", expectedResult, div(num1, num2) );

}

private int div(int a, int b) {
    return a/b;
}
}