remove usage of set from rspec-core and replace with an internal lookupset which uses a hash

Author: JonRowe

lib/rspec/core.rb

@@ -11,6 +11,7 @@
   version
   warnings
 
+  lookup_set
   flat_map
   filter_manager
   dsl

lib/rspec/core/configuration.rb

@@ -306,7 +306,7 @@ def initialize
 
         @mock_framework = nil
         @files_or_directories_to_run = []
-        @loaded_spec_files = Set.new
+        @loaded_spec_files = LookupSet.new
         @color = false
         @pattern = '**{,/*/**}/*_spec.rb'
         @exclude_pattern = ''

lib/rspec/core/configuration_options.rb

@@ -1,6 +1,5 @@
 require 'erb'
 require 'shellwords'
-require 'set'
 
 module RSpec
   module Core
@@ -53,12 +52,12 @@ def organize_options
         end
       end
 
-      UNFORCED_OPTIONS = [
+      UNFORCED_OPTIONS = LookupSet.new([
         :requires, :profile, :drb, :libs, :files_or_directories_to_run,
         :full_description, :full_backtrace, :tty
-      ].to_set
+      ])
 
-      UNPROCESSABLE_OPTIONS = [:formatters].to_set
+      UNPROCESSABLE_OPTIONS = LookupSet.new([:formatters])
 
       def force?(key)
         !UNFORCED_OPTIONS.include?(key)

lib/rspec/core/formatters.rb

@@ -196,8 +196,8 @@ def built_in_formatter(key)
     end
 
     def notifications_for(formatter_class)
-      formatter_class.ancestors.inject(Set.new) do |notifications, klass|
-        notifications + Loader.formatters.fetch(klass) { Set.new }
+      formatter_class.ancestors.inject(::RSpec::Core::LookupSet.new) do |notifications, klass|
+        notifications.merge Loader.formatters.fetch(klass) { ::RSpec::Core::LookupSet.new }
       end
     end
 

lib/rspec/core/formatters/deprecation_formatter.rb

@@ -1,5 +1,4 @@
 RSpec::Support.require_rspec_core "formatters/helpers"
-require 'set'
 
 module RSpec
   module Core
@@ -13,7 +12,7 @@ class DeprecationFormatter
         def initialize(deprecation_stream, summary_stream)
           @deprecation_stream = deprecation_stream
           @summary_stream = summary_stream
-          @seen_deprecations = Set.new
+          @seen_deprecations = LookupSet.new
           @count = 0
         end
         alias :output :deprecation_stream

lib/rspec/core/lookup_set.rb

@@ -0,0 +1,41 @@
+module RSpec
+  module Core
+    # @private
+    #
+    # We use this to replace `::Set` so we can have the advantage of
+    # constant time key lookups for unique arrays but without the
+    # potential to pollute a developers environment with an extra
+    # piece of the stdlib. This helps to prevent false positive
+    # builds.
+    #
+    class LookupSet
+      include Enumerable
+
+      def initialize(array=[])
+        @values = {}
+        merge(array)
+      end
+
+      def <<(key)
+        @values[key] = true
+        self
+      end
+
+      def each(&block)
+        @values.keys.each(&block)
+        self
+      end
+
+      def include?(key)
+        @values.key?(key)
+      end
+
+      def merge(values)
+        values.each do |key|
+          @values[key] = true
+        end
+        self
+      end
+    end
+  end
+end

lib/rspec/core/metadata_filter.rb

@@ -147,8 +147,8 @@ class QueryOptimized < UpdateOptimized
 
         def initialize(applies_predicate)
           super
-          @applicable_keys   = Set.new
-          @proc_keys         = Set.new
+          @applicable_keys   = LookupSet.new
+          @proc_keys         = LookupSet.new
           @memoized_lookups  = Hash.new do |hash, applicable_metadata|
             hash[applicable_metadata] = find_items_for(applicable_metadata)
           end

lib/rspec/core/reporter.rb

@@ -1,10 +1,9 @@
-require 'set'
 module RSpec::Core
   # A reporter will send notifications to listeners, usually formatters for the
   # spec suite run.
   class Reporter
     # @private
-    RSPEC_NOTIFICATIONS = Set.new(
+    RSPEC_NOTIFICATIONS = LookupSet.new(
       [
         :close, :deprecation, :deprecation_summary, :dump_failures, :dump_pending,
         :dump_profile, :dump_summary, :example_failed, :example_group_finished,
@@ -14,7 +13,7 @@ class Reporter
 
     def initialize(configuration)
       @configuration = configuration
-      @listeners = Hash.new { |h, k| h[k] = Set.new }
+      @listeners = Hash.new { |h, k| h[k] = LookupSet.new }
       @examples = []
       @failed_examples = []
       @pending_examples = []

spec/rspec/core/formatters/base_text_formatter_spec.rb

@@ -52,7 +52,7 @@
     end
 
     def output_from_running(example_group)
-      allow(RSpec.configuration).to receive(:loaded_spec_files) { [File.expand_path(__FILE__)].to_set }
+      allow(RSpec.configuration).to receive(:loaded_spec_files) { RSpec::Core::LookupSet.new([File.expand_path(__FILE__)]) }
       example_group.run(reporter)
       examples = example_group.examples
       send_notification :dump_summary, summary_notification(1, examples, examples, [], 0)

spec/rspec/core/lookup_set_spec.rb

@@ -0,0 +1,23 @@
+RSpec.describe 'RSpec::Core::LookupSet' do
+
+  let(:set) { RSpec::Core::LookupSet.new([1, 2, 3]) }
+
+  it 'takes an array of values' do
+    expect(set).to include(1, 2, 3)
+  end
+
+  it 'can be appended to' do
+    set << 4
+    expect(set).to include 4
+  end
+
+  it 'can have more values merged in' do
+    set.merge([4, 5]).merge([6])
+    expect(set).to include(4, 5, 6)
+  end
+
+  it 'is enumerable' do
+    expect(set).to be_an Enumerable
+    expect { |p| set.each(&p) }.to yield_successive_args(1, 2, 3)
+  end
+end

spec/rspec/core_spec.rb

@@ -4,7 +4,6 @@
   fake_libs = File.expand_path('../../support/fake_libs', __FILE__)
   allowed_loaded_features = [
     /optparse\.rb/,   # Used by OptionParser.
-    /set\.rb/,        # used in a few places but being removed in #1870.
     /rbconfig\.rb/,   # loaded by rspec-support for OS detection.
     /shellwords\.rb/, # used by ConfigurationOptions and RakeTask.
     /stringio/,       # Used by BaseFormatter.