Add context cancellation to backup routines

[eticzon]

This should get the ball rolling on issue #110. Please review 😄

I did notice that the project doesn't have an overarching test strategy/implementation in place, hence the reason for the lack of test(s).

I wanted to get your opinion on how to add (or start) adding some test suites onto the project @nilslice. I was thinking of maybe using something like https://github.com/spf13/afero for mocking the uploads/ directory. WDYT?

[nilslice]

@eticzon - thank you! this looks great. I will give it a spin and get back to you with any changes.

Re: testing.. yes, we're desperately short on tests. I knew I would be working on the internal API and the interfaces a bit, and thus didn't want to slow down dev to keep tests up to date, but it's gotten a little out of hand ;)

Frankly, testing is easily the domain I have the least amount of experience in and would be hugely grateful to anyone who could step up to establish some starting point to get things going in the right direction for Ponzu's test strategy. I need to refactor quite a bit of the HTTP handler code to be testable, and I'm sure there is a lot elsewhere to fix up. The APIs are mostly ready to be frozen for an upcoming v1.0, so now is definitely a good time to start writing tests.

I looked at afero and it looks useful -- not only for the uploads but the CLI too. Commands new, add, build, and run in the CLI make use of certain directories on disk that could also benefit from testing with that package. If you'd like to use it, please go ahead! I am currently putting all** dependencies into vendor, flattening and checking them in (but removing their .git directory first to not submodule).

** except Bleve search, since it is a very large codebase.

[eticzon]

@nilslice cool! Thanks! Yup just @mention me if you need some changes done.

Re: tests, glad that you liked the afero idea. If it's OK with you, I'll write up a summary on a issue with a rough plan on getting started with testing. It'll take a while and by that time the handler code will be in an a more testable state like you said.

[nilslice]

Re: tests, glad that you liked the afero idea. If it's OK with you, I'll write up a summary on a issue with a rough plan on getting started with testing.

That would be great, thank you 👍

It'll take a while and by that time the handler code will be in an a more testable state like you said.

Perfect. Thanks again for the help.

[nilslice]

@eticzon - Tested on all 3 backup sources and manually killing the request triggered the cancellation. Thank you!

[eticzon]

👍 Glad I was able to help.