time helpers honor the application time zone when passed a date

Rails applications are expected to be always aware of the application
time zone.

To be consistent with that contract, we have to assume that a bare
date passed to time helpers is a date in the application time zone,
not in the system time zone. The system time zone is irrelevant, we
should totally ignore it.

For example,

    travel_to user.birth_date + 40.years

should make that user be 40th years old regardless of the system
time zone. Without this patch that may not be true.

1 files changed, 19 insertions, 4 deletions

diff --git a/activesupport/lib/active_support/testing/time_helpers.rb b/activesupport/lib/active_support/testing/time_helpers.rb
index 9e0a3d6345..b36f3cf94c 100644
--- a/activesupport/lib/active_support/testing/time_helpers.rb
+++ b/activesupport/lib/active_support/testing/time_helpers.rb
@@ -61,14 +61,23 @@ module ActiveSupport
         travel_to Time.now + duration, &block
       end
 
-      # Changes current time to the given time by stubbing +Time.now+ and +Date.today+ to return the
-      # time or date passed into this method.
+      # Changes current time to the given time by stubbing +Time.now+ and
+      # +Date.today+ to return the time or date passed into this method.
       #
       #   Time.current # => Sat, 09 Nov 2013 15:34:49 EST -05:00
       #   travel_to Time.new(2004, 11, 24, 01, 04, 44)
       #   Time.current # => Wed, 24 Nov 2004 01:04:44 EST -05:00
       #   Date.current # => Wed, 24 Nov 2004
       #
+      # Dates are taken as their timestamp at the beginning of the day in the
+      # application time zone. <tt>Time.current</tt> returns said timestamp,
+      # and <tt>Time.now</tt> its equivalent in the system time zone. Similarly,
+      # <tt>Date.current</tt> returns a date equal to the argument, and
+      # <tt>Date.today</tt> the date according to <tt>Time.now</tt>, which may
+      # be different. (Note that you rarely want to deal with <tt>Time.now</tt>,
+      # or <tt>Date.today</tt>, in order to honor the application time zone
+      # please always use <tt>Time.current</tt> and <tt>Date.current</tt>.)
+      #
       # This method also accepts a block, which will return the current time back to its original
       # state at the end of the block:
       #
@@ -78,8 +87,14 @@ module ActiveSupport
       #   end
       #   Time.current # => Sat, 09 Nov 2013 15:34:49 EST -05:00
       def travel_to(date_or_time, &block)
-        simple_stubs.stub_object(Time, :now, date_or_time.to_time)
-        simple_stubs.stub_object(Date, :today, date_or_time.to_date)
+        if date_or_time.is_a?(Date) && !date_or_time.is_a?(DateTime)
+          now = date_or_time.midnight.to_time
+        else
+          now = date_or_time.to_time
+        end
+
+        simple_stubs.stub_object(Time, :now, now)
+        simple_stubs.stub_object(Date, :today, now.to_date)
 
         if block_given?
           block.call