How do I test exceptions in a parameterized test?
In contrast to what other suggest, I would not introduce any kind of logic to tests - even simple ifs!
What you should have are two testing methods:
- first one takes valid parameters (and expects some output)
- second takes invalid parameters (and expects exceptions)
Not sure if JUnit with its constructor-based parametrized testing is able to do this. Probably you would have to create two test classes for this. Go with JUnit Params or TestNG which offer much more convenient solution.
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;
}
}