remove Ping#current_time and revert back o Time.now.

cover method revert by adding time cop.

app/models/ping.rb

@@ -12,15 +12,11 @@ def unknown?
   end
 
   def seconds_ago
-    current_time.to_i - last_seen.to_i
+    Time.now.to_i - last_seen.to_i
   end
 
   def state
     return "unknown" if unknown?
     status
   end
-
-  def current_time
-    Time.now
-  end
 end

test/test_helper.rb

@@ -1,6 +1,7 @@
 ENV["RAILS_ENV"] = "test"
 require File.expand_path('../../config/environment', __FILE__)
 require 'rails/test_help'
+require 'timecop'
 
 class ActiveSupport::TestCase
   # Setup all fixtures in test/fixtures/*.(yml|csv) for all tests in alphabetical order.

test/unit/ping_test.rb

@@ -49,14 +49,16 @@ class PingTest < ActiveSupport::TestCase
   end
 
   test "seconds_ago" do 
-    present = Time.now
-    time_change = 100
-    past = present - time_change
-
+    time = Time.now
+    time_change = 10
     ping = Ping.new
-    ping.expects(:current_time).returns(present)
-    ping.expects(:last_seen).returns(past)
 
-    assert_equal(ping.seconds_ago, time_change, "true")
+    Timecop.freeze(time) do 
+      ping.last_seen = Time.now
+    end
+
+    Timecop.travel(time + time_change) do 
+      assert_equal(ping.seconds_ago, time_change, "true")
+    end
   end
 end