Here you have defined `RSpec::Mocks::SuperClass` and `RSpec::Mocks::SubClass`.  Other specs need super and sub class fixtures as well, and we've avoided conflicts by making them anonymous (or using `stub_const` if they really need a name for the duration of the example).

Thoughts on doing this instead?

``` ruby
super_class = Class.new do
  def foo; 'bar'; end
end
sub_class = Class.new(super_class)
```