Initial specs for retry filter - they test if it works at all, basically

Change Retry filter to have attribute :configuration and first pass at setting up a listener

Reorganize spec file

Finish adding tests for re-running flaky test cases - all but one pass

Fix spec that said to test what happens when a test case passes but actually didn't make sure it did pass

lib/cucumber/filters/retry.rb

@@ -0,0 +1,19 @@
+require 'cucumber/core/filter'
+require 'cucumber/running_test_case'
+require 'cucumber/events/bus'
+require 'cucumber/events/after_test_case'
+
+module Cucumber
+  module Filters
+    class Retry < Core::Filter.new(:configuration)
+
+      def test_case(test_case)
+        super 
+
+        configuration.on_event(:after_test_case) do |event|
+          test_case.describe_to(receiver) if event.result.failed?
+        end
+      end
+    end
+  end
+end

spec/cucumber/filters/retry_spec.rb

@@ -0,0 +1,73 @@
+require 'cucumber'
+require 'cucumber/filters/retry'
+require 'cucumber/core/gherkin/writer'
+require 'cucumber/configuration'
+require 'cucumber/core/test/case'
+require 'cucumber/core'
+require 'cucumber/events'
+
+describe Cucumber::Filters::Retry do 
+  include Cucumber::Core::Gherkin::Writer
+  include Cucumber::Core
+  include Cucumber::Events
+
+  let(:configuration) { Cucumber::Configuration.new(:retry => 2) }
+  let(:test_case) { Cucumber::Core::Test::Case.new([double('test steps')], double('source').as_null_object) }
+  let(:receiver) { double('receiver').as_null_object }
+  let(:filter) { Cucumber::Filters::Retry.new(configuration, receiver) }
+  let(:fail) { Cucumber::Events::AfterTestCase.new(test_case, double('result', :failed? => true, :ok? => false)) }
+  let(:pass) { Cucumber::Events::AfterTestCase.new(test_case, double('result', :failed? => false, :ok? => true)) }
+
+  it { is_expected.to respond_to(:test_case) }
+  it { is_expected.to respond_to(:with_receiver) }
+  it { is_expected.to respond_to(:done) }
+
+  context "general" do 
+    before(:each) do 
+      filter.with_receiver(receiver)
+    end
+
+    it "registers the :after_test_case event" do 
+      expect(configuration).to receive(:on_event).with(:after_test_case)
+      filter.test_case(test_case)
+    end
+  end
+
+  context "passing test case" do
+    it "describes the test case once" do 
+      expect(test_case).to receive(:describe_to).with(receiver)
+      filter.test_case(test_case)
+      configuration.notify(pass)
+    end
+  end
+
+  context "failing test case" do 
+    it "describes the test case the specified number of times" do 
+      expect(test_case).to receive(:describe_to).with(receiver).exactly(3).times
+      filter.test_case(test_case)
+      configuration.notify(fail)
+    end
+  end
+
+  context "flaky test cases" do 
+
+    context "a little flaky" do 
+      it "describes the test case twice" do 
+        expect(test_case).to receive(:describe_to).with(receiver).exactly(2).times
+        filter.test_case(test_case)
+        configuration.notify(fail)
+        configuration.notify(pass)
+      end
+    end
+
+    context "really flaky" do 
+      it "describes the test case 3 times" do
+        expect(test_case).to receive(:describe_to).with(receiver).exactly(3).times
+        filter.test_case(test_case)
+        configuration.notify(fail)
+        configuration.notify(fail)
+        configuration.notify(pass)
+      end
+    end
+  end
+end