rspec/rspec-core — pull request #1636 by nicklink483 (2014-07-15 23:06:06+00:00)
Title: describe parameters can now be classes without error

Adding to_s on my_description allows my_description to be a class.

Before, the following code would create an error:

describe "An instance of", Dog do
it "sleeps all day" do
expect(@dog).to be_asleep?
end
end

This is because it passed Dog to my_description and an could not be added to the string before it.