Write number of examples to file

With the --count-examples-only switch, write the number of examples
to file in a no_of_examples directory. Also include the tag when
--tag is used.

qa/qa/ee/scenario/test/geo.rb

@@ -41,6 +41,9 @@ module QA
               end
             end
 
+            # Save the scenario class name
+            QA::Runtime::Scenario.define(:klass, self.class.name)
+
             Specs::Runner.perform do |specs|
               specs.tty = true
               specs.tags = self.class.focus

qa/qa/scenario/template.rb

@@ -32,6 +32,9 @@ module QA
         #   Given *gitlab_address* = 'http://gitlab-abc123.test/' #=> http://about.gitlab-abc123.test/
         Runtime::Scenario.define(:about_address, URI(-> { gitlab_address.host = "about.#{gitlab_address.host}"; gitlab_address }.call).to_s) # rubocop:disable Style/Semicolon
 
+        # Save the scenario class name
+        Runtime::Scenario.define(:klass, self.class.name)
+
         ##
         # Setup knapsack and download latest report
         #

qa/qa/specs/runner.rb

@@ -7,6 +7,7 @@ module QA
   module Specs
     class Runner < Scenario::Template
       attr_accessor :tty, :tags, :options
+      RegexMismatchError = Class.new(StandardError)
 
       DEFAULT_TEST_PATH_ARGS = ['--', File.expand_path('./features', __dir__)].freeze
       DEFAULT_STD_ARGS = [$stderr, $stdout].freeze
@@ -72,16 +73,48 @@ module QA
         elsif Runtime::Scenario.attributes[:count_examples_only]
           args.unshift('--dry-run')
           out = StringIO.new
+
           RSpec::Core::Runner.run(args.flatten, $stderr, out).tap do |status|
             abort if status.nonzero?
           end
-          $stdout.puts out.string.match(/(\d+) examples,/)[1]
+
+          begin
+            total_examples = out.string.match(/(\d+) examples?,/)[1]
+          rescue StandardError
+            raise RegexMismatchError, 'Rspec output did not match regex'
+          end
+
+          filename = build_filename
+
+          File.open(filename, 'w') { |f| f.write(total_examples) } if total_examples.to_i > 0
+
+          $stdout.puts "Total examples in #{Runtime::Scenario.klass}: #{total_examples}#{total_examples.to_i > 0 ? ". Saved to file: #{filename}" : ''}"
         else
           RSpec::Core::Runner.run(args.flatten, *DEFAULT_STD_ARGS).tap do |status|
             abort if status.nonzero?
           end
         end
       end
+
+      private
+
+      def build_filename
+        filename = Runtime::Scenario.klass.split('::').last(3).join('_').downcase
+
+        tags = []
+        options.reduce do |before, after|
+          tags << after if %w[--tag -t].include?(before)
+          after
+        end
+        tags = tags.compact.join('_')
+
+        filename.concat("_#{tags}") unless tags.empty?
+
+        filename.concat('.txt')
+
+        FileUtils.mkdir_p('no_of_examples')
+        File.join('no_of_examples', filename)
+      end
     end
   end
 end

qa/spec/specs/runner_spec.rb

@@ -14,6 +14,7 @@ RSpec.describe QA::Specs::Runner do
       allow(QA::Runtime::Browser).to receive(:configure!)
 
       QA::Runtime::Scenario.define(:gitlab_address, "http://gitlab.test")
+      QA::Runtime::Scenario.define(:klass, "QA::Scenario::Test::Instance::All")
     end
 
     it_behaves_like 'excludes orchestrated, transient, and geo'
@@ -43,6 +44,43 @@ RSpec.describe QA::Specs::Runner do
         subject.perform
       end
 
+      it 'writes to file when examples are more than zero' do
+        allow(RSpec::Core::Runner).to receive(:run).and_return(0)
+
+        expect(File).to receive(:open).with('no_of_examples/test_instance_all.txt', 'w') { '22' }
+
+        subject.perform
+      end
+
+      it 'does not write to file when zero examples' do
+        out.string = '0 examples,'
+        allow(RSpec::Core::Runner).to receive(:run).and_return(0)
+
+        expect(File).not_to receive(:open)
+
+        subject.perform
+      end
+
+      it 'raises error when Rspec output does not match regex' do
+        out.string = '0'
+        allow(RSpec::Core::Runner).to receive(:run).and_return(0)
+
+        expect { subject.perform }
+          .to raise_error(QA::Specs::Runner::RegexMismatchError, 'Rspec output did not match regex')
+      end
+
+      context 'when --tag is specified as an option' do
+        subject { described_class.new.tap { |runner| runner.options = %w[--tag actioncable] } }
+
+        it 'includes the option value in the file name' do
+          expect_rspec_runner_arguments(['--dry-run', '--tag', '~geo', '--tag', 'actioncable', *described_class::DEFAULT_TEST_PATH_ARGS], [$stderr, anything])
+
+          expect(File).to receive(:open).with('no_of_examples/test_instance_all_actioncable.txt', 'w') { '22' }
+
+          subject.perform
+        end
+      end
+
       after do
         QA::Runtime::Scenario.attributes.delete(:count_examples_only)
       end