Question

Given this class:

class First
  def to_s ; "Hello World" ; end
end

and this spec:

require 'first'

describe First do
  describe "#to_s" do
    it { should == "Hello World" }
  end
end

I get:

Failures:

  1) First#to_s 
     Failure/Error: it { should == "Hello World" }
       expected: "Hello World"
            got: Hello World (using ==)
       Diff:
       @@ -1,2 +1,2 @@
       -"Hello World"
       +Hello World
     # ./spec/first_spec.rb:5:in `block (3 levels) in <top (required)>'

But I would expect this to pass. My questions are:

• How would a passing spec look like?
• Why is this spec not passing, specifically?

Answer 1

Your outer describe block:

describe First do

sets the subject of the inner examples to be an instance of First. That is, all of the its you’re describing will be a First object. The text #to_s example doesn’t instruct rspec to call to_s on the object.

Since First.new is not equal to "Hello World" the spec fails.

However, since rspec does call to_s on the object to output it in the failure description, “Hello World” does appear there. You could try the following to ensure that the string conversion is being tested:

its(:to_s) { should == "Hello World" }