Make error when getting certificates more transparent for user

[datosh]

As discussed in #69 , user should be informed about nature of error during HTTP get. Since multierr was already used in this project I opted for this solution.

I also added 3 unit tests.
Let me know if I missed anything, since the code involved sleeps I made sure to keep it simple.

go test -count 100 ./verify/trust/ runs in 0.2s on my machine.

[deeglaze]

This is technically a "mock" and not a fake, since it doesn't offer the full functionality of the tested interface. It has set input/output behaviors. I think probably it'd be better to adapt the Getter implementation in testing/mocks.go to suit your needs rather than implement something similar where it can't be reused.

[datosh]

Thanks! I didn't notice the mocks in testing folder.
I have moved my mock over to testing. I opted to keep it as two seperate mocks, since combining it with the available testing.Getter to be both configurable in inputs and (mutliple) outputs seems like a lot of complexity for a mock. Let me know if you agree!
I also had to create trust_test package to break an import cycle back to verify/trust from fakekds.go.

[deeglaze]

This construction is error-prone due to the unchecked expectation that the arrays are the same length, and that Get will not be called more times than there are entries. There is an additional test condition I'm not sure you want to test, but that is that all the responses that you prepared got discharged–maybe you want to have a Done(t testing.TB) function that errors if that expectation isn't met.

I also am not keen on the Get semantics being call order dependent across different URLs.

Maybe we can have Responses map[string][]GetResponse

with type GetResponse struct {
Occurrences uint
Body []byte
Error error
}

Such that Occurrences is decremented each time it's retrieved, and then if decremented to 0, the array gets the 0th item sliced off.
This makes len(g.Responses[url]) == 0 always a testing internal error that you can return.

[datosh]

Thanks - these are great points. PTAL at the updated implementation.

Two more things:

This makes len(g.Responses[url]) == 0 always a testing internal error that you can return.

When you say return error, do you mean like the errors.New("404") you as with the existing Getter? I can also see making this even more strict and Fail the test in case there are no configured URLs or no more prepared responses.

Do you want me to merge the two Getter implementations at this point? I also see value in keeping the simple Getter as well, so that tests can use the simpler construction and prevent the verbosity of constructing the responses.

[deeglaze]

I think returning a 404 error is a helpful alternative, to avoid having to code every 404 response yourself. That would allow the two implementations to merge more seamlessly. You can change current &test.Getter{Responses: m} constructions to test.SimpleGetter(m) to construct the more involved type underneath. Occurrences could be set to uint max (^uint(0)) in this case.

[datosh]

Works for me! I updated the implementation.

[deeglaze]

The linter found a typo, but otherwise looks good.