Change to improved rspec example selection

lib/mutant/integration/rspec.rb

@@ -43,6 +43,8 @@ def initialize(*)
       # @return [self]
       def setup
         @runner.setup($stderr, $stdout)
+        example_group_map
+        reset_examples
         self
       end
       memoize :setup
@@ -53,8 +55,7 @@ def setup
       #
       # @return [Result::Test]
       def call(tests)
-        examples = tests.map(&all_tests_index)
-        filter_examples(&examples.public_method(:include?))
+        setup_examples(tests.map(&all_tests_index))
         start = timer.now
         passed = @runner.run_specs(@rspec_world.ordered_example_groups).equal?(EXIT_SUCCESS)
         Result::Test.new(
@@ -73,6 +74,16 @@ def all_tests
 
     private
 
+      def reset_examples
+        @rspec_world.filtered_examples.each_value(&:clear)
+      end
+
+      def setup_examples(examples)
+        examples.each do |example|
+          @rspec_world.filtered_examples.fetch(example_group_map.fetch(example)) << example
+        end
+      end
+
       def all_tests_index
         all_examples.each_with_index.with_object({}) do |(example, example_index), index|
           index[parse_example(example, example_index)] = example
@@ -95,6 +106,15 @@ def parse_example(example, index)
         )
       end
 
+      def example_group_map
+        @rspec_world.example_groups.flat_map(&:descendants).each_with_object({}) do |example_group, map|
+          example_group.examples.each do |example|
+            map[example] = example_group
+          end
+        end
+      end
+      memoize :example_group_map
+
       def parse_metadata(metadata)
         if metadata.key?(:mutant_expression)
           expression = metadata.fetch(:mutant_expression)
@@ -119,12 +139,6 @@ def all_examples
         end
       end
 
-      def filter_examples(&predicate)
-        @rspec_world.filtered_examples.each_value do |examples|
-          examples.keep_if(&predicate)
-        end
-      end
-
     end # Rspec
   end # Integration
 end # Mutant

spec/unit/mutant/integration/rspec_spec.rb

@@ -77,42 +77,44 @@
     )
   end
 
-  let(:examples) do
-    [
-      example_a,
-      example_b,
-      example_c,
-      example_d,
-      example_e,
-      example_f
-    ]
+  let(:leaf_example_group) do
+    class_double(
+      RSpec::Core::ExampleGroup,
+      'leaf example group',
+      examples: [example_a, example_b, example_c, example_d, example_e, example_f]
+    )
+  end
+
+  let(:root_example_group) do
+    class_double(
+      RSpec::Core::ExampleGroup,
+      'root example group',
+      examples: []
+    )
   end
 
   let(:example_groups) do
-    [
-      double(
-        'root example group',
-        descendants: [
-          double('example group', examples: examples)
-        ]
-      )
-    ]
+    [root_example_group]
   end
 
   let(:filtered_examples) do
     {
-      double('Key') => examples.dup
+      root_example_group => root_example_group.examples.dup,
+      leaf_example_group => leaf_example_group.examples.dup
     }
   end
 
   let(:rspec_world) do
-    double(
-      'rspec-world',
-      example_groups:    example_groups,
-      filtered_examples: filtered_examples
+    instance_double(
+      RSpec::Core::World,
+      example_groups:         example_groups,
+      filtered_examples:      filtered_examples,
+      ordered_example_groups: ordered_example_groups
     )
   end
 
+  let(:ordered_example_groups) { double('ordered_example_groups') }
+
   let(:all_tests) do
     [
       Mutant::Test.new(
@@ -139,6 +141,10 @@
   end
 
   before do
+    allow(root_example_group).to receive_messages(
+      descendants: [root_example_group, leaf_example_group]
+    )
+
     expect(RSpec::Core::ConfigurationOptions).to receive(:new)
       .with(%w[spec --fail-fast])
       .and_return(rspec_options)
@@ -172,20 +178,40 @@
   end
 
   describe '#call' do
-    subject { object.call(tests) }
+    subject { object.setup; object.call(tests) }
 
     let(:tests) { [all_tests.fetch(0)] }
 
     before do
-      expect(rspec_world).to receive(:ordered_example_groups) do
-        filtered_examples.values.flatten
+      expect(rspec_runner).to receive(:setup) do |error, stdout|
+        expect(error).to be($stderr)
+        expect(stdout).to be($stdout)
+      end
+      allow(rspec_runner).to receive_messages(run_specs: exit_status)
+    end
+
+    shared_examples '#call' do
+      it 'calls rspec runner with ordeded examples' do
+        subject
+
+        expect(rspec_runner).to have_received(:run_specs).with(ordered_example_groups)
+      end
+
+      it 'modifies filtered examples to selection' do
+        subject
+
+        expect(filtered_examples).to eql(
+          root_example_group => [],
+          leaf_example_group => [example_a]
+        )
       end
-      expect(rspec_runner).to receive(:run_specs).with([example_a]).and_return(exit_status)
     end
 
     context 'on unsuccessful exit' do
       let(:exit_status) { 1 }
 
+      include_examples '#call'
+
       it 'should return failed result' do
         expect(subject).to eql(
           Mutant::Result::Test.new(
@@ -199,6 +225,8 @@
     context 'on successful exit' do
       let(:exit_status) { 0 }
 
+      include_examples '#call'
+
       it 'should return passed result' do
         expect(subject).to eql(
           Mutant::Result::Test.new(