Add API for tests to describe what they're checking
We've recently started adding comments in code before new tests, to explain what they do in prose.
In !177 (merged) I said the following
I don't know TAP very well, but it looks like it's possible to have a description for tests. Maybe therefore a
g_test_description (gchar *)
function would be nice so that test runners can display this information if they want to.
We should consider whether it's possible / desirable to add this.