Simplify test case creation

[boyska]

While working on #158 I found it hard to generate the *.expected files. So I looked at test.py and modified it:

• run_single_test has no forceargument anymore. I don't know if there was any case in which it was passed, indeed.
• the equivalent of it is the environment variable FORCE_TESTDATA_CREATION ; set it to 1 and you are now in "force mode"
• in force mode, only missing files are created. existing files are not overwritten

The workflow to create a test case is now much simpler:

• create 1.config insde data/mysuite/
• run env FORCE_TESTDATA_CREATION=1 python3 -m unittest. This will show you which files have been created, reporting them as errors.
• Now you can run python3 -m unittest and it should pass
• Of course, you need to check if you like the result
• You might also need to anonymize Message-IDs

Hope you like it!

[amiryal]

I was also working on a patch and didn’t understand how to generate a new .expected file without modifying if force: to if True: temporarily. In the case of creating a new .expected, your proposed changes make it straightforward. It becomes trickier when you need to update an existing file, in which case you would have to delete the old one before running with FORCE_TESTEDATA_CREATION=1. This is good enough, though, so LGTM.

[Ekleog]

This looks great to me too, thank you! I'll add a few lines to the readme after landing, so it's easier to know about this :)