Add `#travel` and `#travel_to` to AS::TestCase

Add `ActiveSupport::Testing::TimeHelpers#travel` and `#travel_to`. These
methods change current time to the given time or time difference by
stubbing `Time.now` and `Date.today` to return the time or date after
the difference calculation, or the time or date that got passed into the
method respectively. These methods also accept a block, which will
return current time back to its original state at the end of the block.

Example for `#travel`:

    Time.now # => 2013-11-09 15:34:49 -05:00
    travel 1.day
    Time.now # => 2013-11-10 15:34:49 -05:00
    Date.today # => Sun, 10 Nov 2013

Example for `#travel_to`:

    Time.now # => 2013-11-09 15:34:49 -05:00
    travel_to Time.new(2004, 11, 24, 01, 04, 44)
    Time.now # => 2004-11-24 01:04:44 -05:00
    Date.today # => Wed, 24 Nov 2004

Both of these methods also accept a block, which will return the current
time back to its original state at the end of the block:

    Time.now # => 2013-11-09 15:34:49 -05:00

    travel 1.day do
      User.create.created_at # => Sun, 10 Nov 2013 15:34:49 EST -05:00
    end

    travel_to Time.new(2004, 11, 24, 01, 04, 44) do
      User.create.created_at # => Wed, 24 Nov 2004 01:04:44 EST -05:00
    end

    Time.now # => 2013-11-09 15:34:49 -05:00

This module is included in `ActiveSupport::TestCase` automatically.

1 files changed, 48 insertions, 2 deletions

diff --git a/activesupport/test/test_test.rb b/activesupport/test/test_test.rb
index 0c8cc1f883..5ed2da7e8b 100644
--- a/activesupport/test/test_test.rb
+++ b/activesupport/test/test_test.rb
@@ -1,4 +1,6 @@
 require 'abstract_unit'
+require 'active_support/core_ext/date'
+require 'active_support/core_ext/numeric/time'
 
 class AssertDifferenceTest < ActiveSupport::TestCase
   def setup
@@ -122,7 +124,6 @@ class SetupAndTeardownTest < ActiveSupport::TestCase
     end
 end
 
-
 class SubclassSetupAndTeardownTest < SetupAndTeardownTest
   setup :bar
   teardown :bar
@@ -143,7 +144,6 @@ class SubclassSetupAndTeardownTest < SetupAndTeardownTest
     end
 end
 
-
 class TestCaseTaggedLoggingTest < ActiveSupport::TestCase
   def before_setup
     require 'stringio'
@@ -156,3 +156,49 @@ class TestCaseTaggedLoggingTest < ActiveSupport::TestCase
     assert_match "#{self.class}: #{name}\n", @out.string
   end
 end
+
+class TimeHelperTest < ActiveSupport::TestCase
+  setup do
+    Time.stubs now: Time.now
+  end
+
+  def test_time_helper_travel
+    expected_time = Time.now + 1.day
+    travel 1.day
+
+    assert_equal expected_time, Time.now
+    assert_equal expected_time.to_date, Date.today
+  end
+
+  def test_time_helper_travel_with_block
+    expected_time = Time.now + 1.day
+
+    travel 1.day do
+      assert_equal expected_time, Time.now
+      assert_equal expected_time.to_date, Date.today
+    end
+
+    assert_not_equal expected_time, Time.now
+    assert_not_equal expected_time.to_date, Date.today
+  end
+
+  def test_time_helper_travel_to
+    expected_time = Time.new(2004, 11, 24, 01, 04, 44)
+    travel_to expected_time
+
+    assert_equal expected_time, Time.now
+    assert_equal Date.new(2004, 11, 24), Date.today
+  end
+
+  def test_time_helper_travel_to_with_block
+    expected_time = Time.new(2004, 11, 24, 01, 04, 44)
+
+    travel_to expected_time do
+      assert_equal expected_time, Time.now
+      assert_equal Date.new(2004, 11, 24), Date.today
+    end
+
+    assert_not_equal expected_time, Time.now
+    assert_not_equal Date.new(2004, 11, 24), Date.today
+  end
+end