Java By Comparison

Parametrize Your Tests

class DistanceConversionTest {

    @Test
    void testConversionRoundTrip() {
        assertRoundTrip(1);
        assertRoundTrip(1_000);
        assertRoundTrip(9_999_999);
    }

    private void assertRoundTrip(int kilometers) {
        Distance expectedDistance = new Distance(
                DistanceUnit.KILOMETERS,
                kilometers
        );

        Distance actualDistance = expectedDistance
                .convertTo(DistanceUnit.MILES)
                .convertTo(DistanceUnit.KILOMETERS);

        Assertions.assertEquals(expectedDistance, actualDistance);
    }
}

Sometimes, you need to test a method or chain of methods in the same way, but with many different input parameters. That’s when you want to make sure that the method works for a large range of values. It’s easy to enumerate the parameters ...