Refactor User#update_last_seen! and User#update_tracked_topics

[novemberkilo]

Improves the score of the User class by refactoring two of its most complex methods (per code climate).

Refactors User#update_last_seen! and User#update_tracked_topics

(This PR was written while wearing a Discourse t-shirt - thanks @SamSaffron 😄)

[discoursebot]

You've signed the CLA, novemberkilo. Thank you! This pull request is ready for review.

[eviltrout]

I've reviewed this PR and it looks good but one thing that scares me is the test coverage for update_last_seen! seems to be poor. How did you test that it works? In browser, looking at the database?

[novemberkilo]

I relied on not breaking any of the current test suite.

[SamSaffron]

thanks @novemberkilo

I agree with @eviltrout here, any way we can increase / improve test coverage here?

[novemberkilo]

@eviltrout @SamSaffron I've generally attempted 'code cleanup' PRs as refactoring exercises that use the current test spec as a marker for whether the refactored code is at least as valid as the code it is replacing. I'm afraid I don't know the business rules for User#update_last_seen! so am not in a position to add test coverage. I know it it tested indirectly through integration tests (because I broke some of them while refactoring, and used them as a way to fixing my code). I'm sorry but I feel there isn't much more I can do here unless I'm given some more direction.

[eviltrout]

Actually I looked again and the coverage is not that bad. Our autotester had a bug that didn't refresh the class properly and I thought it was much worse. I'm happy to accept this, thanks!