Right after you learn to include helpful messages in your test failures, you will immediately encounter the problem of failure messages which are incredibly long.
If only the test runner wasn't so one-dimensional!
Luckily, while procrastinating on fixing a failing unit test, I found out how to get it to display multiline output.
To achieve this, we need the fail( ) method which has an extra detail parameter, which will work with multiline strings. \n line endings are needed in the detail string, because \r ends up being displayed as # in the test runner.
If we combine this with the quit-no parameter, we can output multiple failures in a row to add as much diagnostic information about the failure as needed.
And if you still can't figure out the problem, just add
level = if_aunit_consants=>severity-low to your assertion.
The error is still there, but it is now tolerable.