From 4c53f58a0fc89dd8bf0ea9abd40b7a198dd13b99 Mon Sep 17 00:00:00 2001
From: George Claghorn <george.claghorn@gmail.com>
Date: Tue, 6 Jan 2015 05:30:04 -0500
Subject: [PATCH] Add #prev_day and #next_day as counterparts to #yesterday and
 #tomorrow for Date, Time, and DateTime

---
 activesupport/CHANGELOG.md                    |  5 +++++
 .../core_ext/date_and_time/calculations.rb    | 22 ++++++++++++++-----
 .../test/core_ext/date_and_time_behavior.rb   | 10 +++++++++
 3 files changed, 31 insertions(+), 6 deletions(-)

diff --git a/activesupport/CHANGELOG.md b/activesupport/CHANGELOG.md
index f301cbbd87..2756f7e0e2 100644
--- a/activesupport/CHANGELOG.md
+++ b/activesupport/CHANGELOG.md
@@ -1,3 +1,8 @@
+*   Add `#prev_day` and `#next_day` counterparts to `#yesterday` and
+    `#tomorrow` for `Date`, `Time`, and `DateTime`.
+
+    *George Claghorn*
+
 *   Add `same_time` option to `#next_week` and `#prev_week` for `Date`, `Time`,
     and `DateTime`.
 
diff --git a/activesupport/lib/active_support/core_ext/date_and_time/calculations.rb b/activesupport/lib/active_support/core_ext/date_and_time/calculations.rb
index 5f16794926..e4bfd9f7c5 100644
--- a/activesupport/lib/active_support/core_ext/date_and_time/calculations.rb
+++ b/activesupport/lib/active_support/core_ext/date_and_time/calculations.rb
@@ -13,12 +13,22 @@ module Calculations
 
     # Returns a new date/time representing yesterday.
     def yesterday
-      advance(:days => -1)
+      advance(days: -1)
+    end
+
+    # Returns a new date/time representing the previous day.
+    def prev_day
+      advance(days: -1)
     end
 
     # Returns a new date/time representing tomorrow.
     def tomorrow
-      advance(:days => 1)
+      advance(days: 1)
+    end
+
+    # Returns a new date/time representing the next day.
+    def next_day
+      advance(days: 1)
     end
 
     # Returns true if the date/time is today.
@@ -125,10 +135,10 @@ def next_week(given_day_in_next_week = Date.beginning_of_week, same_time: false)
 
     # Returns a new date/time representing the next weekday.
     def next_weekday
-      if tomorrow.on_weekend?
+      if next_day.on_weekend?
         next_week(:monday, same_time: true)
       else
-        tomorrow
+        next_day
       end
     end
 
@@ -159,10 +169,10 @@ def prev_week(start_day = Date.beginning_of_week, same_time: false)
 
     # Returns a new date/time representing the previous weekday.
     def prev_weekday
-      if yesterday.on_weekend?
+      if prev_day.on_weekend?
         copy_time_to(beginning_of_week(:friday))
       else
-        yesterday
+        prev_day
       end
     end
     alias_method :last_weekday, :prev_weekday
diff --git a/activesupport/test/core_ext/date_and_time_behavior.rb b/activesupport/test/core_ext/date_and_time_behavior.rb
index 6b6e1a2a4c..784547bdf8 100644
--- a/activesupport/test/core_ext/date_and_time_behavior.rb
+++ b/activesupport/test/core_ext/date_and_time_behavior.rb
@@ -6,11 +6,21 @@ def test_yesterday
     assert_equal date_time_init(2005,2,28,10,10,10), date_time_init(2005,3,2,10,10,10).yesterday.yesterday
   end
 
+  def test_prev_day
+    assert_equal date_time_init(2005,2,21,10,10,10), date_time_init(2005,2,22,10,10,10).prev_day
+    assert_equal date_time_init(2005,2,28,10,10,10), date_time_init(2005,3,2,10,10,10).prev_day.prev_day
+  end
+
   def test_tomorrow
     assert_equal date_time_init(2005,2,23,10,10,10), date_time_init(2005,2,22,10,10,10).tomorrow
     assert_equal date_time_init(2005,3,2,10,10,10),  date_time_init(2005,2,28,10,10,10).tomorrow.tomorrow
   end
 
+  def test_next_day
+    assert_equal date_time_init(2005,2,23,10,10,10), date_time_init(2005,2,22,10,10,10).next_day
+    assert_equal date_time_init(2005,3,2,10,10,10),  date_time_init(2005,2,28,10,10,10).next_day.next_day
+  end
+
   def test_days_ago
     assert_equal date_time_init(2005,6,4,10,10,10),  date_time_init(2005,6,5,10,10,10).days_ago(1)
     assert_equal date_time_init(2005,5,31,10,10,10),   date_time_init(2005,6,5,10,10,10).days_ago(5)
-- 
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