Feature: Contract tests with spies

  Whenever you spy on method invocations, it creates a contract specifying that some method can be called with a particular set of arguments. It can be automatically verified by Bogus, whether the method was actually called with those arguments.

  Background:
    Given a file named "library.rb" with:
    """ruby
    class Library
      def checkout(book)
      end
    end
    """

    Given a file named "student.rb" with:
    """ruby
    class Student
      def read(book, library = Library.new)
        library.checkout(book)
        # ...
      end
    end
    """

    And a spec file named "student_spec.rb" with:
    """ruby
    require_relative 'student'
    require_relative 'library'

    describe Student do
      fake(:library)

      it "reads books from library" do
        student = Student.new

        student.read("Moby Dick", library)

        expect(library).to have_received.checkout("Moby Dick")
      end
    end
    """

  Scenario: Stubbing methods that exist on real object
    Then spec file with following content should pass:
    """ruby
    require_relative 'library'

    describe Library do
      verify_contract(:library)

      it "checks out books" do
        library = Library.new

        library.checkout("Moby Dick")

        # ...
      end
    end
    """

  Scenario: Verifing that stubbed methods are tested
    Then spec file with following content should fail:
    """ruby
    require_relative 'library'

    describe Library do
      verify_contract(:library)
    end
    """

  Scenario: Verifying that methods are tested with right arguments
    Then spec file with following content should fail:
    """ruby
    require_relative 'library'

    describe Library do
      verify_contract(:library)

      it "checks out books" do
        library = Library.new

        library.checkout("Moby Dick 2: The ulitmate")

        # ...
      end
    end
    """