(j)Unit testing assertions and error messages?

Question

I am currently testing a method, let me call it testedMethod().

The body of the method looks like this

private testedMethod(List<Protocoll> protocolList) {
    //so something with the protocolList
    if (something) && (somethingElse) {
        Assert.isFalse(areTheProtocollsCorrect(p1, p2), "Error, the protocols are wrong");
    }

    if (somethingCompeletlyElse) && (somethingElse) {
        Assert.isFalse(areTheProtocollsExactlyTheSame(p1, p2), "Error, the protocols are the same");
    }
}

Additional code from the Assert.class:

isFalse:

public static void isFalse(boolean condition, String descr) {
    isTrue(!condition, descr);
}

isTrue:

public static void isTrue(boolean condition, String descr) {
    if (!condition) {
        fail(descr);
    }
}

fail:

public static void fail(String descr) {
    LOGGER.fatal("Assertion failed: " + descr);
    throw new AssertException(descr);
}

Testing what the method should do correctly is allready done. But I would like to test those assertions. This assertions are an important part of the code, and I would like to see if the method is throwing those errors when I provide wrong data to it. How can I do it using JUnit?

You have jUnit `Assert` in your code? Is it Spring `Assert`? If Spring, check for `IAE`s. — Dave Newton, Nov 12 '15 at 20:52
What does `Assert.isFalse()` do? If it's your own code you should include it in the question. — kryger, Nov 12 '15 at 20:53
@kryger @Dave Newton - I have added the methods from `Assert.class` — hc0re, Nov 12 '15 at 20:59
So check for the exception. I don't understand what the issue is, I guess. — Dave Newton, Nov 12 '15 at 20:59

score 1 · Accepted Answer · answered Nov 12 '15 at 21:12

In the first place, I you are currently using JUnit, you shouldn't code your own assert* or fail methods: They are already included in the Assert class.

Anyway, if you want to test your assertions, you have to code two kind of test cases: positive cases and negative (failing) cases:

@Test
public void positiveCase1()
{
    // Fill your input parameters with data that you know must work:
    List<Protocoll> protocolList=...
    testedMethod(protocolList);
}

@Test
public void positiveCase2()
{
    ...
}

@Test(expected=AssertException.class)
public void negativeCase1()
{
    // Fill your input parameters with data that you know must NOT work:
    List<Protocoll> protocolList=...
    testedMethod(protocolList);
}

@Test(expected=AssertException.class)
public void negativeCase2()
{
    ...
}

The expected parameter in the Test annotation makes JUnit check that an exception of that type was raised. Else, the test is marked as failed.

But I still insist in that it's better to use the JUnit standards.

Thanks for the answer, still, I am using the JUnit assertions. The other assertions in my code have completely other purpose and they are not used in JUnit tests :) — hc0re, Nov 12 '15 at 21:31

(j)Unit testing assertions and error messages?

1 Answers1