Ensuring tests pass on gccgo

[John Meinel]

Please don't actually slow down the time it takes to land code to trunk by
actually running the tests 2x in a row (and IME gccgo test suite is
actually more than 1x the time for the golang test suite to run).
I suppose if you can put them in parallel, but I'd really like to see it
just be a CI test.

John
=:->



On Thu, May 22, 2014 at 5:43 AM, Ian Booth <ian.booth at canonical.com> wrote:

> Hi folks
>
> We are working to make all juju-core unit tests pass using gccgo. In case
> you
> didn't already know, there's a common issue which has caused a lot of the
> failures to date. Here's a quick heads up on how to deal with it.
>
> golang-go and gcc-go have different map implementations which results in
> ordering differences, affecting things like range etc (simplistically put,
> gcc-go's map ordering is random whereas currently golang-go is somewhat
> deterministic). Now of course, maps are unordered but what we sometimes do
> in
> the code is to use a map to hold some data (maybe to eliminate duplicates)
> and
> then expose that data via a slice or array. If we then do a c.Assert(v1,
> gc.DeepEquals, v2), it will fail on gcc-go, since the order of items in
> the 2
> slices is different, even though the values are the same.
>
> In such cases, we need to ensure that we use jc.SameContents rather than
> DeepEquals. By "such cases", that means where we truly only care about the
> contents of the data and not the order.
>
> Here's a brief example, a snippet of code taken from a constraints test.
>
> cons := constraints.MustParse(t.cons)
> unsupported, err := validator.Validate(cons)
> if t.err == "" {
>         c.Assert(err, gc.IsNil)
>         c.Assert(unsupported, jc.SameContents, t.unsupported)
> } else {
>         c.Assert(err, gc.ErrorMatches, t.err)
> }
>
> Above, "unsupported" is a []string of attribute names. We don't care what
> order
> they are returned in from Validate(), just that the correct values are all
> there. So instead of:
>
> c.Assert(unsupported, jc.DeepEquals, t.unsupported)
>
> we needed to change it to:
>
> c.Assert(unsupported, jc.SameContents, t.unsupported)
>
> The need to use SameContents depends on the internal implementation of the
> code
> under test. But as a general rule, if we use SameContents where we are
> saying
> that order of results is not relevant, then we can be sure tests will pass
> on
> gcc-go as well as golang-go.
>
> If unsure, please test on gcc-go using something like:
>
> go test --compiler=gccgo <blah>
>
> We will soon be gating trunk landings based on *both* golang-go and gcc-go
> having successful test runs and we'd like it if we didn't introduce more
> test
> failures to fix in the interim.
>
>
>
>
>
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