I believe I have seen this happen before, where in the test I'm expecting a validation error but none occurs and I get a message when I run the test saying no Diagnostic message has been found. However, it doesn't seem to happen all of the time. For example, in test choice_errorNotSuppressed_validationErrorCheck, I have a validationErrors block where I expect the error DUMMYERROR. However, the test passes.

Test is in
daffodil-test/src/test/resources/edu/illinois/ncsa/daffodil/section02/validation_errors/Validation.tdml