adding a found WTF

[evelyn-fyi]

When mocking an Id in Apex, such that:

    public static Id getMockId(SObjectType sObjType) {
        idsGenerated++;
        String keyPrefix = sObjType.getDescribe().getKeyPrefix();
        String idsGenStr = String.valueOf(idsGenerated);

        return Id.valueOf(keyPrefix + idsGenStr.leftPad(13-idsGenStr.length(), '0'));
    }

...the following Assert passes, although it should not:

Assert.areNotEqual(EmailMessages.getFormattedThreadingToken(mockId), EmailMessages.getFormattedThreadingToken(mockId), 'these should be the same, but they aren't');

One would expect this to remain constant. The documentation for getFormattedThreadingToken(recordId) states that the threading token should be the same for a given caseId so that all emails will be associated to that case, eg, "In this sample, we send an email with a threading token so that the email and any responses are associated with the related case."