co19 tests - add tests for enhanced enums

[devoncarew]

[devoncarew]

(I haven't looked to see whether we already have these tests)

[eernstg]

@sgrekhov, @iarkh, could you add a comment here when you consider these tests done?

[sgrekhov]

@devoncarew @eernstg, for now tests for Enhanced Enums are mainly completed. Spec was slightly changed and I need to check these changes and update the tests accordingly. I'll let you know when I'll finish with it. Don't thuink that it'll take much time