Merge pull request #775 from mbj/add/clock-monotonic

Add Mutant::Timer

Changelog.md

@@ -1,3 +1,7 @@
+# v0.8.20 2018-11-25
+
+* Replace internal timers with monotonic ones.
+
 # v0.8.19 2018-11-06
 
 * Drop support for Ruby < 2.5

lib/mutant.rb

@@ -177,6 +177,7 @@ require 'mutant/expression/method'
 require 'mutant/expression/methods'
 require 'mutant/expression/namespace'
 require 'mutant/test'
+require 'mutant/timer'
 require 'mutant/integration'
 require 'mutant/selector'
 require 'mutant/selector/expression'

lib/mutant/env.rb

@@ -42,7 +42,7 @@ module Mutant
     #
     # rubocop:disable MethodLength
     def run_mutation_tests(mutation)
-      start = Time.now
+      start = Timer.now
       tests = selector.call(mutation.subject)
 
       config.isolation.call do
@@ -53,7 +53,7 @@ module Mutant
       Result::Test.new(
         output:  error.message,
         passed:  false,
-        runtime: Time.now - start,
+        runtime: Timer.now - start,
         tests:   tests
       )
     end

lib/mutant/integration/minitest.rb

@@ -82,7 +82,7 @@ module Mutant
       def call(tests)
         test_cases = tests.map(&all_tests_index.method(:fetch))
         output     = StringIO.new
-        start      = Time.now
+        start      = Timer.now
 
         reporter = ::Minitest::SummaryReporter.new(output)
 
@@ -98,7 +98,7 @@ module Mutant
           passed:  reporter.passed?,
           tests:   tests,
           output:  output.read,
-          runtime: Time.now - start
+          runtime: Timer.now - start
         )
       end
 

lib/mutant/integration/rspec.rb

@@ -61,13 +61,13 @@ module Mutant
       def call(tests)
         examples = tests.map(&all_tests_index.method(:fetch))
         filter_examples(&examples.method(:include?))
-        start = Time.now
+        start = Timer.now
         passed = @runner.run_specs(@world.ordered_example_groups).equal?(EXIT_SUCCESS)
         @output.rewind
         Result::Test.new(
           output:  @output.read,
           passed:  passed,
-          runtime: Time.now - start,
+          runtime: Timer.now - start,
           tests:   tests
         )
       end

lib/mutant/runner/sink.rb

@@ -10,7 +10,7 @@ module Mutant
       # @return [undefined]
       def initialize(*)
         super
-        @start           = Time.now
+        @start           = Timer.now
         @subject_results = {}
       end
 
@@ -20,7 +20,7 @@ module Mutant
       def status
         Result::Env.new(
           env:             env,
-          runtime:         Time.now - @start,
+          runtime:         Timer.now - @start,
           subject_results: @subject_results.values
         )
       end

lib/mutant/timer.rb

@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+module Mutant
+  module Timer
+    # Monotonic elapsed time of block execution
+    #
+    # @return [Float]
+    def self.elapsed
+      start = now
+      yield
+      now - start
+    end
+
+    # The now monotonic time
+    #
+    # @return [Float]
+    def self.now
+      Process.clock_gettime(Process::CLOCK_MONOTONIC)
+    end
+  end # Timer
+end # Mutant

spec/support/corpus.rb

@@ -79,7 +79,7 @@ module MutantSpec
       #   otherwise
       def verify_mutation_generation
         checkout
-        start = Time.now
+        start = Mutant::Timer.now
 
         options = {
           finish:       method(:finish),
@@ -90,7 +90,7 @@ module MutantSpec
         total = Parallel.map(effective_ruby_paths, options, &method(:count_mutations_and_check_errors))
           .inject(DEFAULT_MUTATION_COUNT, :+)
 
-        took = Time.now - start
+        took = Mutant::Timer.now - start
         puts MUTATION_GENERATION_MESSAGE % [total, took, total / took]
         self
       end

spec/unit/mutant/clock_monotonic_spec.rb

@@ -0,0 +1,52 @@
+# frozen_string_literal: true
+
+RSpec.describe Mutant::Timer do
+  let(:events) { [] }
+
+  let(:times) { [1.0, 2.0] }
+
+  before do
+    allow(Process).to receive(:clock_gettime) do |argument|
+      expect(argument).to be(Process::CLOCK_MONOTONIC)
+
+      events << :clock_gettime
+
+      times.fetch(events.count(:clock_gettime).pred)
+    end
+  end
+
+  describe '.elapsed' do
+    def apply
+      described_class.elapsed { events << :yield }
+    end
+
+    it 'executes events in expected sequence' do
+      expect { apply }
+        .to change(events, :to_a)
+        .from([])
+        .to(%i[clock_gettime yield clock_gettime])
+    end
+
+    it 'returns elapsed time' do
+      expect(apply).to be(1.0)
+    end
+  end
+
+  describe '.now' do
+    def apply
+      described_class.now
+    end
+
+    it 'returns current monotonic time' do
+      expect(apply).to be(1.0)
+      expect(apply).to be(2.0)
+    end
+
+    it 'calls expected system API' do
+      expect { apply }
+        .to change(events, :to_a)
+        .from([])
+        .to(%i[clock_gettime])
+    end
+  end
+end

spec/unit/mutant/env_spec.rb

@@ -57,7 +57,7 @@ RSpec.describe Mutant::Env do
         .with(mutation_subject)
         .and_return(tests)
 
-      allow(Time).to receive_messages(now: Time.at(0))
+      allow(Mutant::Timer).to receive(:now).and_return(2.0, 3.0)
     end
 
     context 'when isolation does not raise error' do
@@ -91,7 +91,7 @@ RSpec.describe Mutant::Env do
         Mutant::Result::Test.new(
           output:  'test-error',
           passed:  false,
-          runtime: 0.0,
+          runtime: 1.0,
           tests:   tests
         )
       end

spec/unit/mutant/integration/rspec_spec.rb

@@ -126,7 +126,7 @@ RSpec.describe Mutant::Integration::Rspec do
       .and_return(rspec_runner)
 
     expect(RSpec).to receive_messages(world: world)
-    allow(Time).to receive_messages(now: Time.now)
+    allow(Mutant::Timer).to receive_messages(now: Mutant::Timer.now)
   end
 
   describe '#all_tests' do

spec/unit/mutant/reporter/cli_spec.rb

@@ -41,7 +41,7 @@ RSpec.describe Mutant::Reporter::CLI do
   end
 
   before do
-    allow(Time).to receive(:now).and_return(Time.now)
+    allow(Mutant::Timer).to receive_messages(now: Mutant::Timer.now)
   end
 
   describe '.build' do

spec/unit/mutant/runner/sink_spec.rb

@@ -19,7 +19,7 @@ describe Mutant::Runner::Sink do
   let(:object) { described_class.new(env) }
 
   before do
-    allow(Time).to receive(:now).and_return(Time.now)
+    allow(Mutant::Timer).to receive_messages(now: Mutant::Timer.now)
   end
 
   describe '#result' do