Add before_register hook to RSpec World

[bootstraponline]

Fix #2078

Use case:

• sauce_rspec/rspec.rb
• SauceRSpec config

Enables running an unmodified test suite on multiple Selenium browsers.

[myronmarston]

I think this should go on config instead of world. Config is where we let users configure callbacks.

Also, example group registration isn't really a concept we've exposed into our API up to now. It's purely an internal. I think that this feature would fit better with RSpec's terminology if it was something like on_example_group_definition, e.g.:

RSpec.configure do |c|
  c.on_example_group_definition do |example_group|
    # do something with the newly defined example group
  end
end

[bootstraponline]

Makes sense. I'll fix.

[bootstraponline]

I updated the PR to use on_example_group_definition instead of before_register. I also fixed the spec so it shows a supported use case. If there's a better way to accomplish the goal without this hook then that'd be great as well.

[myronmarston]

@bootstraponline I think what you have here is reasonable as far as a way to hook in to example group creation in RSpec. But to generate additional examples that are essentially clones of existing ones w/ some modifications, we should provide you with some new APIs. Here's what I'm thinking...

• ExampleGroup needs new public APIs like ExampleGroup.add_example and ExampleGroup.remove_example
• Example needs a new public API like duplicate_with(metadata_overrides).

Then for your case I think you could do something like this:

RSpec.configure do |config|
  config. on_example_group_definition do |group|
    group.examples.each do |example|
      group.remove_example example

      [{:browserName => :firefox}, {:browserName => :chrome}].each do |cap|
        group.add_example example.duplicate_with(:cap => cap)
      end
    end
  end
end

Thoughts?

[bootstraponline]

That looks awesome!

[myronmarston]

That looks awesome!

Want to open up PRs adding those APIs? (and/or add them to this one)?

[bootstraponline]

Want to open up PRs adding those APIs? (and/or add them to this one)?

I think they're better as independent PRs. I'll work on submitting a new PR for ExampleGroup and another for Example.

add_example/remove_example should be easy. duplicate_with is a bit more tricky since rspec will delete tests if they share the same id so I'll have to change it to something else (maybe add a hash of the metadata?).

[myronmarston]

duplicate_with is a bit more tricky since rspec will delete tests if they share the same id so I'll have to change it to something else (maybe add a hash of the metadata?).

I'd recommend not doing anything with the ids. In fact, don't even use dup or clone -- instead, just instantiate a new instance of Example and RSpec will take care of the rest. Essentially you'd do something similar to what RSpec does here:

rspec-core/lib/rspec/core/example_group.rb

Lines 139 to 145 in b8f0270

	desc, *args = *all_args
	options = Metadata.build_hash_from(args)
	options.update(:skip => RSpec::Core::Pending::NOT_YET_IMPLEMENTED) unless block
	options.update(extra_options)
	example = RSpec::Core::Example.new(self, desc, options, block)

In fact, it might be as simple as:

Example.new(example.example_group_class, example.description, example.metadata, example.example_block)

[bootstraponline]

Ok, I'll try it.

[bootstraponline]

I squashed to one commit and Travis is passing. appveyor had an internal server error unrelated to the PR.

[bootstraponline]

I submitted #2095 for add/remove example. Working on duplicate_with next.

[JonRowe]

LGTM