Question

I’m testing a WeekConverter for Xalan use and wondering what is my test exactly doing. 😀

Having the following test method:

@Test(expected = IllegalArgumentException.class)
  public void testConvertTwoDigitYearWithWrongInput() {
  WeekConverter weekConverter = new WeekConverter(WeekConverter.Strategy.TWO_DIGIT_YEAR);

  //wrong or empty inputs
  assertEquals("0", weekConverter.convert(""));
  assertEquals("0", weekConverter.convert("abcdefgh"));
}

Will this test expect an exception for all asserts, or only for the first assert? If only the first, which would mean that I have to create a test method for each assert, although I’m expecting the same exception in both cases. Can someone confirm my example here, please?

I also have a test for null, which yields a NullPointerException. The soft validation is the following:

if (inputDate == null) {
  do something and throw NullPointerexception
} else if (inputDate.isEmpty()) {
  do something and throw IllegalArgumentException, since inputDate is not really null
} else if (inputDate.matches(regex)) {
  go futher and convert
} else {
  do something and throw IllegalArgumentException, since inputDate does not match regex
}

Therefore the one test method expecting IllegalArgumentException with two asserts. But it’s obvious that I need two different test methods, not only to respect functionality of JUnit , but also that I expect a throw from two different states.

Answer 1

You can break your method into multiple methods, but if you have many input samples it would be inconvenient.

You can use the following approach instead:

@Test
public void testConvertTwoDigitYearWithWrongInput() {
    WeekConverter weekConverter = new WeekConverter(WeekConverter.Strategy.TWO_DIGIT_YEAR); 

    assertFailsToConvert(weekConverter, ""); 
    assertFailsToConvert(weekConverter, "abcdefgh");
}

private void assertFailsToConvert(WeekConverter weekConverter, String input) {
    try {
        weekConverter.convert(input);
        fail("Should not convert [" + input + "]");
    } catch (IllegalArgumentException ex) {}
}