From 86d636ec0a2923fa28493b497e77321bff0a33c0 Mon Sep 17 00:00:00 2001
From: Cezary Baginski <cezary@chronomantic.net>
Date: Fri, 18 Mar 2016 18:20:30 +0100
Subject: [PATCH] guarantee sleep for :grace_period [fix #114]

---
 Gemfile                                       |  2 +
 lib/guard/livereload.rb                       |  3 +-
 lib/guard/livereload/guaranteed_sleep.rb      | 14 ++++
 .../guard/livereload/guaranteed_sleep_spec.rb | 64 +++++++++++++++++++
 spec/lib/guard/livereload_spec.rb             | 12 +++-
 5 files changed, 92 insertions(+), 3 deletions(-)
 create mode 100644 lib/guard/livereload/guaranteed_sleep.rb
 create mode 100644 spec/lib/guard/livereload/guaranteed_sleep_spec.rb

diff --git a/Gemfile b/Gemfile
index 2216fd1..0600883 100644
--- a/Gemfile
+++ b/Gemfile
@@ -7,10 +7,12 @@ group :development do
   gem "guard-rspec", require: false
   gem "guard-rubocop", require: false
   gem "hound-tools", '~> 0.0.4', require: false
+  gem 'timecop'
 end
 
 group :test do
   gem "coveralls", require: false
   gem "rake", require: false
   gem 'rspec', '~> 3.1'
+  gem 'timecop'
 end
diff --git a/lib/guard/livereload.rb b/lib/guard/livereload.rb
index 1ca1153..bcd1aa5 100644
--- a/lib/guard/livereload.rb
+++ b/lib/guard/livereload.rb
@@ -5,6 +5,7 @@ class LiveReload < Plugin
     require 'guard/livereload/websocket'
     require 'guard/livereload/reactor'
     require 'guard/livereload/snippet'
+    require 'guard/livereload/guaranteed_sleep'
 
     attr_accessor :reactor, :options
 
@@ -37,7 +38,7 @@ def stop
     end
 
     def run_on_modifications(paths)
-      sleep options[:grace_period]
+      GuaranteedSleep.new.sleep(options[:grace_period])
       reactor.reload_browser(paths)
     end
   end
diff --git a/lib/guard/livereload/guaranteed_sleep.rb b/lib/guard/livereload/guaranteed_sleep.rb
new file mode 100644
index 0000000..29e0f2a
--- /dev/null
+++ b/lib/guard/livereload/guaranteed_sleep.rb
@@ -0,0 +1,14 @@
+require 'guard/compat/plugin'
+
+module Guard
+  class LiveReload < Plugin
+    class GuaranteedSleep
+      def sleep(seconds)
+        deadline = Time.now + seconds
+        while (remaining = deadline - Time.now) > 0
+          Kernel.sleep(remaining)
+        end
+      end
+    end
+  end
+end
diff --git a/spec/lib/guard/livereload/guaranteed_sleep_spec.rb b/spec/lib/guard/livereload/guaranteed_sleep_spec.rb
new file mode 100644
index 0000000..b344851
--- /dev/null
+++ b/spec/lib/guard/livereload/guaranteed_sleep_spec.rb
@@ -0,0 +1,64 @@
+require 'guard/compat/test/helper'
+
+require 'timecop'
+
+RSpec.describe Guard::LiveReload::GuaranteedSleep do
+  let(:start_time) { Time.local(2006, 3, 18, 2, 0) }
+
+  let(:implementation) { Kernel }
+
+  around do |example|
+    Timecop.freeze(start_time) do
+      example.run
+    end
+  end
+
+  describe '.sleep' do
+    before do
+      @interruptions = interruptions
+      allow(implementation).to receive(:sleep) do |time|
+        t = (@interruptions > 0 ? (time.to_f / 2) : time)
+        @interruptions -= 1
+        Timecop.travel(Time.now + t)
+        t
+      end
+    end
+
+    context 'with 0' do
+      let(:interruptions) { 0 }
+
+      it 'never sleeps' do
+        subject.sleep(0)
+        expect(implementation).to_not receive(:sleep)
+        expect(Time.now).to be_within(0.05).of(start_time)
+      end
+    end
+
+    context 'when never interrupted' do
+      let(:interruptions) { 0 }
+
+      it 'waits before reloading the browser' do
+        subject.sleep(5)
+        expect(Time.now).to be_within(0.1).of(start_time + 5)
+      end
+    end
+
+    context 'when interrupted once' do
+      let(:interruptions) { 1 }
+
+      it 'waits before reloading the browser' do
+        subject.sleep(5)
+        expect(Time.now).to be_within(0.1).of(start_time + 5)
+      end
+    end
+
+    context 'when interrupted many times' do
+      let(:interruptions) { 3 }
+
+      it 'waits before reloading the browser' do
+        subject.sleep(5)
+        expect(Time.now).to be_within(0.1).of(start_time + 5)
+      end
+    end
+  end
+end
diff --git a/spec/lib/guard/livereload_spec.rb b/spec/lib/guard/livereload_spec.rb
index 4a09ad0..aa2f96d 100644
--- a/spec/lib/guard/livereload_spec.rb
+++ b/spec/lib/guard/livereload_spec.rb
@@ -153,14 +153,22 @@
   end
 
   describe '#run_on_modifications' do
+    let(:sleeper) { instance_double(Guard::LiveReload::GuaranteedSleep) }
+
+    before do
+      allow(reactor).to receive(:reload_browser)
+      allow(Guard::LiveReload::GuaranteedSleep).to receive(:new).and_return(sleeper)
+      allow(sleeper).to receive(:sleep)
+    end
+
     it 'reloads browser' do
       expect(reactor).to receive(:reload_browser).with(['foo'])
       plugin.run_on_modifications(['foo'])
     end
 
-    it 'can wait 0.5 seconds before reloading the browser' do
+    it 'waits given time before reloading the browser' do
       expect(reactor).to receive(:reload_browser).with(['foo'])
-      expect(plugin).to receive(:sleep).with(0.5)
+      allow(sleeper).to receive(:sleep).with(0.5)
       plugin.options[:grace_period] = 0.5
       plugin.run_on_modifications(['foo'])
     end