wrap Time.now for testability

lib/limiter.rb

@@ -1,5 +1,6 @@
 # frozen_string_literal: true
 
+require 'limiter/clock'
 require 'limiter/mixin'
 require 'limiter/rate_queue'
 require 'limiter/version'

lib/limiter/clock.rb

@@ -0,0 +1,30 @@
+# frozen_string_literal: true
+
+require 'singleton'
+
+module Limiter
+  class Clock
+    include Singleton
+
+    extend SingleForwardable
+    def_single_delegators :instance, :skip, :time
+
+    def initialize
+      @offset = 0
+    end
+
+    def skip(interval)
+      @offset += interval
+    end
+
+    def time
+      now + @offset
+    end
+
+    private
+
+    def now
+      Time.now
+    end
+  end
+end

lib/limiter/rate_queue.rb

@@ -21,7 +21,7 @@ def shift
 
         sleep_until(time + @interval)
 
-        @ring[@head] = Time.now
+        @ring[@head] = Clock.time
         @head = (@head + 1) % @size
       end
 
@@ -31,7 +31,7 @@ def shift
     private
 
     def sleep_until(time)
-      interval = time - Time.now
+      interval = time - Clock.time
       return unless interval.positive?
       sleep(interval)
     end

test/limiter/clock_test.rb

@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+require 'test_helper'
+
+module Limiter
+  class ClockTest < Minitest::Test
+    def setup
+      super
+      @start_time = Clock.time
+    end
+
+    def test_clock_is_advancing
+      assert Clock.time > @start_time
+    end
+
+    def test_skips_interval
+      Clock.skip(300)
+      assert Clock.time >= (@start_time + 300)
+    end
+  end
+end

test/test_helper.rb

@@ -10,7 +10,7 @@ module Limiter
   module FakeSleep
     def setup
       super
-      RateQueue.send(:define_method, :sleep) { |i| Timecop.travel(Time.now + i) }
+      RateQueue.send(:define_method, :sleep) { |i| Clock.skip(i) }
     end
 
     def teardown
@@ -21,11 +21,11 @@ def teardown
 
   module AssertElapsed
     def assert_elapsed(interval)
-      started_at = Time.now.to_f
+      started_at = Clock.time
 
       yield
 
-      completed_at = Time.now.to_f
+      completed_at = Clock.time
 
       assert_in_delta started_at + interval, completed_at, 1.1
     end