I'm generally not a fan of before hooks and ivars.  ivars spring into existence when referenced, which means you'll get a `NoMethodError` for `nil` if the ivar is renamed or typod.  (Or, in the pathological case, you could get a false positive for an expectation like `expect(@some_mispelled_ivar).to be_nil`, where it's only nil because you misspelled it, not because the `@foo = Foo.foo` line in `before` returned `nil` like you expected).

Instead I would tend to favor `let` for this:

``` ruby
let(:group) { ExampleGroup.describe { pending { fail } } }

it 'generates a pending example' do
  group.run
  expect(group.examples.first).to be_pending
end

# ...
```

Any reason you chose the `before`/ivar route?