Enum representing the types of visibility that can be applied to the results of the hidden unit tests.

• HIDE_EVERYTHING - students will receive no information about hidden tests;
• SHOW_OK_NOK - students will be informed about if they pass all the tests or if there is at least one failure;
• SHOW_PROGRESS - students will know how many tests exist and how many they are passing (e.g. nr passed/nr total).