Add tests for Callables.bisect

This was previously untested, so I've added coverage to match the other
options that generate callable runners. I anticipate extracting this to
directly test the callables, but haven't yet decided how best to achieve this.

Author: urbanautomaton

lib/rspec/core/option_parser.rb

@@ -69,7 +69,7 @@ def parser(options)
 
         parser.on('--bisect[=verbose]', 'Repeatedly runs the suite in order to isolate the failures to the ',
                   '  smallest reproducible case.') do |argument|
-          options[:bisect] = argument
+          options[:bisect] = argument || true
           options[:runner] = Callables.bisect
         end
 

spec/rspec/core/option_parser_spec.rb

@@ -1,4 +1,5 @@
 require 'rspec/core/drb'
+require 'rspec/core/bisect/coordinator'
 require 'rspec/core/project_initializer'
 
 module RSpec::Core
@@ -391,8 +392,86 @@ def generate_help_text
       end
     end
 
-    describe '--bisect' do
+    describe "--bisect" do
+      it "sets the `:bisect` option" do
+        options = Parser.parse(%w[ --bisect ])
 
+        expect(options[:bisect]).to be_truthy
+      end
+
+      it "sets a the `:runner` option with a callable" do
+        options = Parser.parse(%w[ --bisect ])
+
+        expect(options[:runner]).to respond_to(:call)
+      end
+
+      context "when the verbose option is specified" do
+        it "records this in the options" do
+          options = Parser.parse(%w[ --bisect=verbose ])
+
+          expect(options[:bisect]).to eq("verbose")
+        end
+      end
+
+      context 'when the runner is called' do
+        let(:args) { double(:args) }
+        let(:err) { double(:stderr) }
+        let(:out) { double(:stdout) }
+        let(:success) { true }
+        let(:configuration_options) { double(:options, :args => args) }
+
+        before do
+          allow(RSpec::Core::Bisect::Coordinator).to receive(:bisect_with).and_return(success)
+        end
+
+        it "starts the bisection coordinator" do
+          options = Parser.parse(%w[ --bisect ])
+          allow(configuration_options).to receive(:options).and_return(options)
+          options[:runner].call(configuration_options, err, out)
+
+          expect(RSpec::Core::Bisect::Coordinator).to have_received(:bisect_with).with(
+            args,
+            RSpec.configuration,
+            Formatters::BisectProgressFormatter
+          )
+        end
+
+        context "when the bisection is successful" do
+          it "returns 0" do
+            options = Parser.parse(%w[ --bisect ])
+            allow(configuration_options).to receive(:options).and_return(options)
+            exit_code = options[:runner].call(configuration_options, err, out)
+
+            expect(exit_code).to eq(0)
+          end
+        end
+
+        context "when the bisection is unsuccessful" do
+          let(:success) { false }
+
+          it "returns 1" do
+            options = Parser.parse(%w[ --bisect ])
+            allow(configuration_options).to receive(:options).and_return(options)
+            exit_code = options[:runner].call(configuration_options, err, out)
+
+            expect(exit_code).to eq(1)
+          end
+        end
+
+        context "and the verbose option is specified" do
+          it "starts the bisection coordinator with the debug formatter" do
+            options = Parser.parse(%w[ --bisect=verbose ])
+            allow(configuration_options).to receive(:options).and_return(options)
+            options[:runner].call(configuration_options, err, out)
+
+            expect(RSpec::Core::Bisect::Coordinator).to have_received(:bisect_with).with(
+              args,
+              RSpec.configuration,
+              Formatters::BisectDebugFormatter
+            )
+          end
+        end
+      end
     end
 
     describe '--profile' do