> It's not specific to minitest; it's a change in how constants are
> resolved. I'm not sure of the exact formulation but what's happening
> is that in a class_eval'd code block (which I think is what describe
> does), 1.8 is looking for a constant scoped to the outer level, while
> 1.9 is looking for one that is scope to the class that's being
> class_evaled.

Interesting.  I expected it would be something like this.  Kinda makes
specs hard to use under 1.8 IMO.  You're left with nesting describes
within a module, or using the full constant name.

  module A
    module B
    end

    describe "Nest in Module" do
      it "should show nesting works" do
        B.must_equal A::B
      end
    end
  end

  describe "Full Constant Name" do
    it "should show full names works" do
      A::B.must_equal A::B
    end
  end