Add feature for any_instance.should_receive use case

features/message_expectations/any_instance.feature

@@ -0,0 +1,19 @@
+Feature: expect a message on any instance of a class
+
+  Use `any_instance.should_receive` to set an expectation that one (and only
+  one) instance of a class receives a message before the example is completed.
+
+  Scenario: expect a message on any instance of a class
+    Given a file named "example_spec.rb" with:
+      """
+      describe "any_instance.should_receive" do
+        it "verifies that one instance of the class receives the message" do
+          Object.any_instance.should_receive(:foo).and_return(:return_value)
+
+          o = Object.new
+          o.foo.should eq(:return_value)
+        end
+      end
+      """
+    When I run `rspec example_spec.rb`
+    Then the output should contain "0 failures"