refactor: vastly simplify guinness2 by removing all context.

[juliemr]

Almost everything that guinness does to keep track of suites
and tests is now also handles by package test. So, instead
of keeping tons of complex logic around, simply defer
to package:test functions when possible.

BREAKING CHANGE:

iit and ddescribe NO LONGER modify which tests will run. Instead,
they will mark those blocks with the tag "solo". To run only
iit or ddescribe blocks, use the command line
pub run test --tags solo (the same command you would use before,
with the additional tags "solo").

See #1

[nex3]

It's probably a good idea to deprecate or remove this priority parameter, since test doesn't support it.

[juliemr]

Thanks for catching that! Done.

[nex3]

Based on my limited knowledge of Guiness, this looks good. A couple larger-scale things that occurred to me:

• It may be worth taking this opportunity to make the matchers more in line with package:matcher, although maybe that's not worth the effort.
• Once you've figured out how you want this to look, I'd suggest returning to the package name guinness. It's unlikely that people will want to use v1 and v2 at the same time, and it always sucks to have a 2 on the end of package names later down the line when version 1 is long gone.
• I generally like to write integration tests in Dart, invoking processes with dart:io or scheduled_test and verifying their output. That may be easier in the long-term than having to run them via a shell script.

[juliemr]

Thanks for taking a look!

Re: matchers - I think that it could make sense to use that as a backend at some point, but agree that this is probably not worth the effort, since the immediate goal is to make them just work with angular2.

I'll talk with victor about merging this back in to guinness without any numbers at the end.

And yeah, if I update the integration tests again I'll definitely move away from just shell scripts.