java.lang.UnsupportedOperationException shown when trying to Assert some values

Question

I am using the below code to assert text in my test script. But its giving UnsupportedOperationException error every time it hits this code.

public static void verifyEquals(Object actual, Object expected) {
        try {
            Assert.assertEquals(actual, expected);
        } catch(Throwable e) {
            addVerificationFailure(e);
        }
    }

    public static List<Throwable> getVerificationFailures() {
        List verificationFailures = verificationFailuresMap.get(Reporter.getCurrentTestResult());
        return verificationFailures == null ? new ArrayList() : verificationFailures;
    }

    private static void addVerificationFailure(Throwable e) {
        StackTraceElement[] error = e.getStackTrace();
        List<StackTraceElement> errors = Arrays.asList(error);
        verificationFailuresMap.put(Reporter.getCurrentTestResult(), errors);
        List verificationFailures = getVerificationFailures();
        verificationFailuresMap.put(Reporter.getCurrentTestResult(), verificationFailures);
        verificationFailures.add(e);
    }

Can anyone help me on this?

Answer 1

This is the problem:

List verificationFailures = getVerificationFailures();
verificationFailuresMap.put(Reporter.getCurrentTestResult(), verificationFailures);
verificationFailures.add(e);

You're calling List.add on the result of Arrays.asList . You can't do that, as the result of Arrays.asList is a view onto the array - you can't add or remove elements.

Additionally - erasure aside - that list is a List<StackTraceElement> - it's backed by a StackTraceElement[] . What does it even mean to add a Throwable to that?

It's simpler to see the problem if you remove the code which puts the list into the map and then fetches it back again before adding:

private static void addVerificationFailure(Throwable e) {
    StackTraceElement[] error = e.getStackTrace();
    List<StackTraceElement> errors = Arrays.asList(error);
    verificationFailuresMap.put(Reporter.getCurrentTestResult(), errors);
    errors.add(e);
}

This will now fail at compile time due to trying to add a Throwable to a List<StackTraceElement> . But even if you were trying to add a StackTraceElement it would still fail due to Arrays.asList not supporting add .

It's really unclear what you're trying to do, but you need to rethink it...