Add Duration#before and #after as aliases for #ago and #since

It's common in test cases at my job to have code like this:

    let(:today) { customer_start_date + 2.weeks }
    let(:earlier_date) { today - 5.days }

With this change, we can instead write

    let(:today) { 2.weeks.after(customer_start_date) }
    let(:earlier_date) { 5.days.before(today) }

Closes #27721

3 files changed, 31 insertions, 0 deletions

diff --git a/activesupport/CHANGELOG.md b/activesupport/CHANGELOG.md
index 2f08d8bc82..0614cdaabd 100644
--- a/activesupport/CHANGELOG.md
+++ b/activesupport/CHANGELOG.md
@@ -1,3 +1,19 @@
+*   Add `ActiveSupport::Duration#before` and `#after` as aliases for `#until` and `#since`
+
+    These read more like English and require less mental gymnastics to read and write.
+
+    Before:
+
+        2.weeks.since(customer_start_date)
+        5.days.until(today)
+
+    After:
+
+        2.weeks.after(customer_start_date)
+        5.days.before(today)
+
+    *Nick Johnstone*
+
 *   Soft-deprecated the top-level `HashWithIndifferentAccess` constant.
     `ActiveSupport::HashWithIndifferentAccess` should be used instead.
 
diff --git a/activesupport/lib/active_support/duration.rb b/activesupport/lib/active_support/duration.rb
index 003f6203ef..70cf78519d 100644
--- a/activesupport/lib/active_support/duration.rb
+++ b/activesupport/lib/active_support/duration.rb
@@ -180,6 +180,7 @@ module ActiveSupport
       sum(1, time)
     end
     alias :from_now :since
+    alias :after :since
 
     # Calculates a new Time or Date that is as far in the past
     # as this Duration represents.
@@ -187,6 +188,7 @@ module ActiveSupport
       sum(-1, time)
     end
     alias :until :ago
+    alias :before :ago
 
     def inspect #:nodoc:
       parts.
diff --git a/activesupport/test/core_ext/duration_test.rb b/activesupport/test/core_ext/duration_test.rb
index 6a275d1d5b..6facb04f1f 100644
--- a/activesupport/test/core_ext/duration_test.rb
+++ b/activesupport/test/core_ext/duration_test.rb
@@ -179,6 +179,19 @@ class DurationTest < ActiveSupport::TestCase
     Time.zone = nil
   end
 
+  def test_before_and_afer
+    t = Time.local(2000)
+    assert_equal t + 1, 1.second.after(t)
+    assert_equal t - 1, 1.second.before(t)
+  end
+
+  def test_before_and_after_without_argument
+    Time.stub(:now, Time.local(2000)) do
+      assert_equal Time.now - 1.second, 1.second.before
+      assert_equal Time.now + 1.second, 1.second.after
+    end
+  end
+
   def test_adding_hours_across_dst_boundary
     with_env_tz "CET" do
       assert_equal Time.local(2009, 3, 29, 0, 0, 0) + 24.hours, Time.local(2009, 3, 30, 1, 0, 0)