Added RSpec matchers to test delegations.

spec/support/matchers/delegate_matchers.rb

@@ -0,0 +1,40 @@
+# RSpec matcher to spec delegations.
+#
+# Usage:
+#
+#     describe Post do
+#       it { should delegate(:name).to(:author).with_prefix } # post.author_name
+#       it { should delegate(:month).to(:created_at) }
+#       it { should delegate(:year).to(:created_at) }
+#     end
+
+RSpec::Matchers.define :delegate do |method|
+  match do |delegator|
+    @method = @prefix ? :"#{@to}_#{method}" : method
+    @delegator = delegator
+    begin
+      @delegator.send(@to)
+    rescue NoMethodError
+      raise "#{@delegator} does not respond to #{@to}!"
+    end
+    @delegator.stub(@to).and_return double('receiver')
+    @delegator.send(@to).stub(method).and_return :called
+    @delegator.send(@method) == :called
+  end
+
+  description do
+    "delegate :#{@method} to its #{@to}#{@prefix ? ' with prefix' : ''}"
+  end
+
+  failure_message_for_should do |text|
+    "expected #{@delegator} to delegate :#{@method} to its #{@to}#{@prefix ? ' with prefix' : ''}"
+  end
+
+  failure_message_for_should_not do |text|
+    "expected #{@delegator} not to delegate :#{@method} to its #{@to}#{@prefix ? ' with prefix' : ''}"
+  end
+
+  chain(:to) { |receiver| @to = receiver }
+  chain(:with_prefix) { @prefix = true }
+
+end