* marc1706/ticket/11579:
[ticket/11579] Add method for validating emails for valid MX and mark as slow
[ticket/11579] Do not extend validate_data_helper
[ticket/11579] Add missing commas to validate_username_test
[ticket/11579] Rework calls to validate_data_helper
[ticket/11579] Move simple tests into seperate files
[ticket/11579] Use test case helper class and use assert prefix for method
[ticket/11579] Move tests into seperate files depending on needed fixture
[ticket/11579] Remove unnecessary globals from validate_password()
[ticket/11579] Add remaining unit tests for validate_data functions
[ticket/11579] Add basic set of unit tests for validate_data()