Further refine license_diff() to determine license info added or license info removed

[steven-esser]

Instead of returning 'license change', we should have indications when the new side now has license info when the old side has none, and vice-versa.

[johnmhoran]

@MaJuRG What labels would you like to use? We could use license added and license removed, but these don't seem to convey the binary nature of what we want to indicate, i.e., that the new/old file has/had no license info.

[steven-esser]

We can probably just use license info added and license info removed for now.

[johnmhoran]

OK.

[johnmhoran]

@MaJuRG Note that, as expected, this new category will be triggered if, for example, one side of the Delta pair has license scores all of which are below the cutoff_score and the other side has at least one license score >= the cutoff_score.

[steven-esser]

@johnmhoran That sounds good. It should also work when one side is missing license info and the other has license info, regardless of score.

[johnmhoran]

I'm glad you mentioned that, @MaJuRG . That adds a slight wrinkle to the new structure of _license_diff() but I think I have in mind a straightforward way to handle it.

This test, for example, currently passes, and we'd also want it to pass if the old_file score were < the cutoff_score:

    def test_Delta_license_diff_new_no_license_info(self):
        new_file = models.File({'path': 'new/path.txt'})
        old_file = models.File({'path': 'old/path.txt', 'licenses': [{'key': 'mit', 'score': 50.0}]})

        result = deltacode.Delta(new_file, old_file, 'modified')

        assert result.category == 'license info removed'

[steven-esser]

yes

[steven-esser]

This is ready for a PR, feel free to open at your convenience.