Create LastRunPersister.

Author: myronmarston

lib/rspec/core.rb

@@ -4,6 +4,7 @@
 
 require "rspec/support"
 RSpec::Support.require_rspec_support "caller_filter"
+RSpec::Support.require_rspec_support "directory_maker"
 
 RSpec::Support.define_optimized_require_for_rspec(:core) { |f| require_relative f }
 
@@ -34,6 +35,7 @@
   example
   shared_example_group
   example_group
+  last_run_persister
 ].each { |name| RSpec::Support.require_rspec_core name }
 
 # Namespace for all core RSpec code.

lib/rspec/core/formatters.rb

@@ -1,4 +1,3 @@
-RSpec::Support.require_rspec_support "directory_maker"
 # ## Built-in Formatters
 #
 # * progress (default) - Prints dots for passing examples, `F` for failures, `*`

lib/rspec/core/last_run_persister.rb

@@ -0,0 +1,37 @@
+module RSpec
+  module Core
+    # Persists data about the last run of your spec suite so that it
+    # can be re-used on the next run. For now, it only stores a list
+    # of what failed in order to support the `--rerun-faliures` flag.
+    # @private
+    class LastRunPersister
+      def self.for_current_project
+        new(File.join(Dir.home, ".rspec_last_run", RubyProject.root))
+      end
+
+      attr_reader :directory
+
+      def initialize(directory)
+        @directory = directory
+      end
+
+      def persist_failures(failure_ids)
+        File.open(failures_file_name, "w") do |f|
+          f.write(failure_ids.join("\n"))
+        end
+      end
+
+      def failures_from_last_run
+        File.read(failures_file_name).split("\n")
+      end
+
+    private
+
+      def failures_file_name
+        @failures_file_name ||= File.join(directory, "failures.txt").tap do |f|
+          RSpec::Support::DirectoryMaker.mkdir_p(File.dirname(f))
+        end
+      end
+    end
+  end
+end

lib/rspec/core/project_initializer.rb

@@ -1,5 +1,3 @@
-RSpec::Support.require_rspec_support "directory_maker"
-
 module RSpec
   module Core
     # @private

spec/rspec/core/last_run_persister_spec.rb

@@ -0,0 +1,52 @@
+module RSpec::Core
+  RSpec.describe LastRunPersister do
+    def persist_failures(dir, failures)
+      LastRunPersister.new(dir).persist_failures(failures)
+    end
+
+    def persisted_from(dir)
+      LastRunPersister.new(dir).failures_from_last_run
+    end
+
+    it 'persists the failures from the last run' do
+      persist_failures("./tmp", %w[ failure1 failure17 ])
+      expect(persisted_from("./tmp")).to eq(%w[ failure1 failure17 ])
+    end
+
+    it 'stomps the failures written the prior time' do
+      persist_failures("./tmp", %w[ failure1 failure17 ])
+      persist_failures("./tmp", %w[ failure2 failure18 ])
+
+      expect(persisted_from("./tmp")).to eq(%w[ failure2 failure18 ])
+    end
+
+    it 'separates its storage based on the given directory name' do
+      FileUtils.mkdir_p("./tmp/project1")
+      FileUtils.mkdir_p("./tmp/project2")
+
+      persist_failures("./tmp/project1", %w[ failure1 ])
+      persist_failures("./tmp/project2", %w[ failure2 ])
+
+      expect(persisted_from("./tmp/project1")).to eq(%w[ failure1 ])
+      expect(persisted_from("./tmp/project2")).to eq(%w[ failure2 ])
+    end
+
+    it 'makes any intermediary directories that do not yet exist so that it can write there' do
+      FileUtils.rm_rf("./tmp/start")
+      persist_failures("./tmp/start/of/long/path", %w[ f1 ])
+      expect(persisted_from("./tmp/start/of/long/path")).to eq(%w[ f1 ])
+    end
+
+    describe ".for_current_project.directory", :isolated_home do
+      let(:dir_for_current_project) { LastRunPersister.for_current_project.directory }
+
+      it 'starts with #{home}/.rspec_last_run so it is scoped to the user' do
+        expect(dir_for_current_project).to start_with(File.join(Dir.home, ".rspec_last_run"))
+      end
+
+      it 'includes the current project path so that it is scoped to the project' do
+        expect(dir_for_current_project).to end_with(RubyProject.root)
+      end
+    end
+  end
+end