Adjust for daylight savings in String#to_time

The changes in b79adc4323 had a bug where if the time in the String
was in standard time but the current time was in daylight savings then
the calculated adjustment was off by an hour.

This commit fixes this and adds extra tests for the following:

* time in string is standard time, current time is standard time
* time in string is standard time, current time is daylight savings
* time in string is daylight savings, current time is standard time
* time in string is daylight savings, current time is daylight savings

Fixes #10306.

2 files changed, 124 insertions, 10 deletions

diff --git a/activesupport/lib/active_support/core_ext/string/conversions.rb b/activesupport/lib/active_support/core_ext/string/conversions.rb
index 428fa1f826..d2a2db32bb 100644
--- a/activesupport/lib/active_support/core_ext/string/conversions.rb
+++ b/activesupport/lib/active_support/core_ext/string/conversions.rb
@@ -20,19 +20,17 @@ class String
     return if parts.empty?
 
     now = Time.now
-    offset = parts[:offset]
-    utc_offset = form == :utc ? 0 : now.utc_offset
-    adjustment = offset ? offset - utc_offset : 0
-
-    Time.send(
-      form,
+    time = Time.new(
       parts.fetch(:year, now.year),
       parts.fetch(:mon, now.month),
       parts.fetch(:mday, now.day),
       parts.fetch(:hour, 0),
       parts.fetch(:min, 0),
-      parts.fetch(:sec, 0) + parts.fetch(:sec_fraction, 0)
-    ) - adjustment
+      parts.fetch(:sec, 0) + parts.fetch(:sec_fraction, 0),
+      parts.fetch(:offset, form == :utc ? 0 : nil)
+    )
+
+    form == :utc ? time.utc : time.getlocal
   end
 
   # Converts a string to a Date value.
diff --git a/activesupport/test/core_ext/string_ext_test.rb b/activesupport/test/core_ext/string_ext_test.rb
index 62c5741ffb..8f0ebc13ea 100644
--- a/activesupport/test/core_ext/string_ext_test.rb
+++ b/activesupport/test/core_ext/string_ext_test.rb
@@ -300,9 +300,9 @@ class StringConversionsTest < ActiveSupport::TestCase
       assert_equal Time.local(2005, 2, 27, 23, 50, 19, 275038), "2005-02-27T23:50:19.275038".to_time
       assert_equal Time.utc(2039, 2, 27, 23, 50), "2039-02-27 23:50".to_time(:utc)
       assert_equal Time.local(2039, 2, 27, 23, 50), "2039-02-27 23:50".to_time
-      assert_equal Time.local(2011, 2, 27, 18, 50), "2011-02-27 13:50 -0100".to_time
+      assert_equal Time.local(2011, 2, 27, 17, 50), "2011-02-27 13:50 -0100".to_time
       assert_equal Time.utc(2011, 2, 27, 23, 50), "2011-02-27 22:50 -0100".to_time(:utc)
-      assert_equal Time.local(2005, 2, 27, 23, 50), "2005-02-27 14:50 -0500".to_time
+      assert_equal Time.local(2005, 2, 27, 22, 50), "2005-02-27 14:50 -0500".to_time
       assert_nil "".to_time
     end
   end
@@ -326,6 +326,122 @@ class StringConversionsTest < ActiveSupport::TestCase
     end
   end
 
+  def test_standard_time_string_to_time_when_current_time_is_standard_time
+    with_env_tz "US/Eastern" do
+      Time.stubs(:now).returns(Time.local(2012, 1, 1))
+      assert_equal Time.local(2012, 1, 1, 10, 0), "2012-01-01 10:00".to_time
+      assert_equal Time.utc(2012, 1, 1, 10, 0), "2012-01-01 10:00".to_time(:utc)
+      assert_equal Time.local(2012, 1, 1, 13, 0), "2012-01-01 10:00 -0800".to_time
+      assert_equal Time.utc(2012, 1, 1, 18, 0), "2012-01-01 10:00 -0800".to_time(:utc)
+      assert_equal Time.local(2012, 1, 1, 10, 0), "2012-01-01 10:00 -0500".to_time
+      assert_equal Time.utc(2012, 1, 1, 15, 0), "2012-01-01 10:00 -0500".to_time(:utc)
+      assert_equal Time.local(2012, 1, 1, 5, 0), "2012-01-01 10:00 UTC".to_time
+      assert_equal Time.utc(2012, 1, 1, 10, 0), "2012-01-01 10:00 UTC".to_time(:utc)
+      assert_equal Time.local(2012, 1, 1, 13, 0), "2012-01-01 10:00 PST".to_time
+      assert_equal Time.utc(2012, 1, 1, 18, 0), "2012-01-01 10:00 PST".to_time(:utc)
+      assert_equal Time.local(2012, 1, 1, 10, 0), "2012-01-01 10:00 EST".to_time
+      assert_equal Time.utc(2012, 1, 1, 15, 0), "2012-01-01 10:00 EST".to_time(:utc)
+    end
+  end
+
+  def test_standard_time_string_to_time_when_current_time_is_daylight_savings
+    with_env_tz "US/Eastern" do
+      Time.stubs(:now).returns(Time.local(2012, 7, 1))
+      assert_equal Time.local(2012, 1, 1, 10, 0), "2012-01-01 10:00".to_time
+      assert_equal Time.utc(2012, 1, 1, 10, 0), "2012-01-01 10:00".to_time(:utc)
+      assert_equal Time.local(2012, 1, 1, 13, 0), "2012-01-01 10:00 -0800".to_time
+      assert_equal Time.utc(2012, 1, 1, 18, 0), "2012-01-01 10:00 -0800".to_time(:utc)
+      assert_equal Time.local(2012, 1, 1, 10, 0), "2012-01-01 10:00 -0500".to_time
+      assert_equal Time.utc(2012, 1, 1, 15, 0), "2012-01-01 10:00 -0500".to_time(:utc)
+      assert_equal Time.local(2012, 1, 1, 5, 0), "2012-01-01 10:00 UTC".to_time
+      assert_equal Time.utc(2012, 1, 1, 10, 0), "2012-01-01 10:00 UTC".to_time(:utc)
+      assert_equal Time.local(2012, 1, 1, 13, 0), "2012-01-01 10:00 PST".to_time
+      assert_equal Time.utc(2012, 1, 1, 18, 0), "2012-01-01 10:00 PST".to_time(:utc)
+      assert_equal Time.local(2012, 1, 1, 10, 0), "2012-01-01 10:00 EST".to_time
+      assert_equal Time.utc(2012, 1, 1, 15, 0), "2012-01-01 10:00 EST".to_time(:utc)
+    end
+  end
+
+  def test_daylight_savings_string_to_time_when_current_time_is_standard_time
+    with_env_tz "US/Eastern" do
+      Time.stubs(:now).returns(Time.local(2012, 1, 1))
+      assert_equal Time.local(2012, 7, 1, 10, 0), "2012-07-01 10:00".to_time
+      assert_equal Time.utc(2012, 7, 1, 10, 0), "2012-07-01 10:00".to_time(:utc)
+      assert_equal Time.local(2012, 7, 1, 13, 0), "2012-07-01 10:00 -0700".to_time
+      assert_equal Time.utc(2012, 7, 1, 17, 0), "2012-07-01 10:00 -0700".to_time(:utc)
+      assert_equal Time.local(2012, 7, 1, 10, 0), "2012-07-01 10:00 -0400".to_time
+      assert_equal Time.utc(2012, 7, 1, 14, 0), "2012-07-01 10:00 -0400".to_time(:utc)
+      assert_equal Time.local(2012, 7, 1, 6, 0), "2012-07-01 10:00 UTC".to_time
+      assert_equal Time.utc(2012, 7, 1, 10, 0), "2012-07-01 10:00 UTC".to_time(:utc)
+      assert_equal Time.local(2012, 7, 1, 13, 0), "2012-07-01 10:00 PDT".to_time
+      assert_equal Time.utc(2012, 7, 1, 17, 0), "2012-07-01 10:00 PDT".to_time(:utc)
+      assert_equal Time.local(2012, 7, 1, 10, 0), "2012-07-01 10:00 EDT".to_time
+      assert_equal Time.utc(2012, 7, 1, 14, 0), "2012-07-01 10:00 EDT".to_time(:utc)
+    end
+  end
+
+  def test_daylight_savings_string_to_time_when_current_time_is_daylight_savings
+    with_env_tz "US/Eastern" do
+      Time.stubs(:now).returns(Time.local(2012, 7, 1))
+      assert_equal Time.local(2012, 7, 1, 10, 0), "2012-07-01 10:00".to_time
+      assert_equal Time.utc(2012, 7, 1, 10, 0), "2012-07-01 10:00".to_time(:utc)
+      assert_equal Time.local(2012, 7, 1, 13, 0), "2012-07-01 10:00 -0700".to_time
+      assert_equal Time.utc(2012, 7, 1, 17, 0), "2012-07-01 10:00 -0700".to_time(:utc)
+      assert_equal Time.local(2012, 7, 1, 10, 0), "2012-07-01 10:00 -0400".to_time
+      assert_equal Time.utc(2012, 7, 1, 14, 0), "2012-07-01 10:00 -0400".to_time(:utc)
+      assert_equal Time.local(2012, 7, 1, 6, 0), "2012-07-01 10:00 UTC".to_time
+      assert_equal Time.utc(2012, 7, 1, 10, 0), "2012-07-01 10:00 UTC".to_time(:utc)
+      assert_equal Time.local(2012, 7, 1, 13, 0), "2012-07-01 10:00 PDT".to_time
+      assert_equal Time.utc(2012, 7, 1, 17, 0), "2012-07-01 10:00 PDT".to_time(:utc)
+      assert_equal Time.local(2012, 7, 1, 10, 0), "2012-07-01 10:00 EDT".to_time
+      assert_equal Time.utc(2012, 7, 1, 14, 0), "2012-07-01 10:00 EDT".to_time(:utc)
+    end
+  end
+
+  def test_partial_string_to_time_when_current_time_is_standard_time
+    with_env_tz "US/Eastern" do
+      Time.stubs(:now).returns(Time.local(2012, 1, 1))
+      assert_equal Time.local(2012, 1, 1, 10, 0), "10:00".to_time
+      assert_equal Time.utc(2012, 1, 1, 10, 0),  "10:00".to_time(:utc)
+      assert_equal Time.local(2012, 1, 1, 6, 0), "10:00 -0100".to_time
+      assert_equal Time.utc(2012, 1, 1, 11, 0), "10:00 -0100".to_time(:utc)
+      assert_equal Time.local(2012, 1, 1, 10, 0), "10:00 -0500".to_time
+      assert_equal Time.utc(2012, 1, 1, 15, 0), "10:00 -0500".to_time(:utc)
+      assert_equal Time.local(2012, 1, 1, 5, 0), "10:00 UTC".to_time
+      assert_equal Time.utc(2012, 1, 1, 10, 0), "10:00 UTC".to_time(:utc)
+      assert_equal Time.local(2012, 1, 1, 13, 0), "10:00 PST".to_time
+      assert_equal Time.utc(2012, 1, 1, 18, 0), "10:00 PST".to_time(:utc)
+      assert_equal Time.local(2012, 1, 1, 12, 0), "10:00 PDT".to_time
+      assert_equal Time.utc(2012, 1, 1, 17, 0), "10:00 PDT".to_time(:utc)
+      assert_equal Time.local(2012, 1, 1, 10, 0), "10:00 EST".to_time
+      assert_equal Time.utc(2012, 1, 1, 15, 0), "10:00 EST".to_time(:utc)
+      assert_equal Time.local(2012, 1, 1, 9, 0), "10:00 EDT".to_time
+      assert_equal Time.utc(2012, 1, 1, 14, 0), "10:00 EDT".to_time(:utc)
+    end
+  end
+
+  def test_partial_string_to_time_when_current_time_is_daylight_savings
+    with_env_tz "US/Eastern" do
+      Time.stubs(:now).returns(Time.local(2012, 7, 1))
+      assert_equal Time.local(2012, 7, 1, 10, 0), "10:00".to_time
+      assert_equal Time.utc(2012, 7, 1, 10, 0), "10:00".to_time(:utc)
+      assert_equal Time.local(2012, 7, 1, 7, 0), "10:00 -0100".to_time
+      assert_equal Time.utc(2012, 7, 1, 11, 0), "10:00 -0100".to_time(:utc)
+      assert_equal Time.local(2012, 7, 1, 11, 0), "10:00 -0500".to_time
+      assert_equal Time.utc(2012, 7, 1, 15, 0), "10:00 -0500".to_time(:utc)
+      assert_equal Time.local(2012, 7, 1, 6, 0), "10:00 UTC".to_time
+      assert_equal Time.utc(2012, 7, 1, 10, 0), "10:00 UTC".to_time(:utc)
+      assert_equal Time.local(2012, 7, 1, 14, 0), "10:00 PST".to_time
+      assert_equal Time.utc(2012, 7, 1, 18, 0), "10:00 PST".to_time(:utc)
+      assert_equal Time.local(2012, 7, 1, 13, 0), "10:00 PDT".to_time
+      assert_equal Time.utc(2012, 7, 1, 17, 0), "10:00 PDT".to_time(:utc)
+      assert_equal Time.local(2012, 7, 1, 11, 0), "10:00 EST".to_time
+      assert_equal Time.utc(2012, 7, 1, 15, 0), "10:00 EST".to_time(:utc)
+      assert_equal Time.local(2012, 7, 1, 10, 0), "10:00 EDT".to_time
+      assert_equal Time.utc(2012, 7, 1, 14, 0), "10:00 EDT".to_time(:utc)
+    end
+  end
+
   def test_string_to_datetime
     assert_equal DateTime.civil(2039, 2, 27, 23, 50), "2039-02-27 23:50".to_datetime
     assert_equal 0, "2039-02-27 23:50".to_datetime.offset # use UTC offset