Merge pull request #35063 from rosa/current-before-reset-callback

Support before_reset callback in CurrentAttributes

3 files changed, 41 insertions, 9 deletions

diff --git a/activesupport/CHANGELOG.md b/activesupport/CHANGELOG.md
index 1e726ceb54..2da774ca66 100644
--- a/activesupport/CHANGELOG.md
+++ b/activesupport/CHANGELOG.md
@@ -1,4 +1,8 @@
-*   Remove the `` Kernel#` `` override that suppresses ENOENT and accidentally returns nil on Unix systems
+*   Add `before_reset` callback to `CurrentAttributes` and define `after_reset` as an alias of `resets` for symmetry.
+
+    *Rosa Gutierrez*
+
+*   Remove the `` Kernel#` `` override that suppresses ENOENT and accidentally returns nil on Unix systems.
 
     *Akinori Musha*
 
@@ -8,7 +12,6 @@
 
     *Stefan Schüßler*
 
-
 ## Rails 6.0.0.beta1 (January 18, 2019) ##
 
 *   Remove deprecated `Module#reachable?` method.
diff --git a/activesupport/lib/active_support/current_attributes.rb b/activesupport/lib/active_support/current_attributes.rb
index 3145ff87a1..67ebe102d7 100644
--- a/activesupport/lib/active_support/current_attributes.rb
+++ b/activesupport/lib/active_support/current_attributes.rb
@@ -119,10 +119,16 @@ module ActiveSupport
         end
       end
 
+      # Calls this block before #reset is called on the instance. Used for resetting external collaborators that depend on current values.
+      def before_reset(&block)
+        set_callback :reset, :before, &block
+      end
+
       # Calls this block after #reset is called on the instance. Used for resetting external collaborators, like Time.zone.
       def resets(&block)
         set_callback :reset, :after, &block
       end
+      alias_method :after_reset, :resets
 
       delegate :set, :reset, to: :instance
 
diff --git a/activesupport/test/current_attributes_test.rb b/activesupport/test/current_attributes_test.rb
index 1669f08f68..adbdc646bc 100644
--- a/activesupport/test/current_attributes_test.rb
+++ b/activesupport/test/current_attributes_test.rb
@@ -3,13 +3,18 @@
 require "abstract_unit"
 
 class CurrentAttributesTest < ActiveSupport::TestCase
-  Person = Struct.new(:name, :time_zone)
+  Person = Struct.new(:id, :name, :time_zone)
 
   class Current < ActiveSupport::CurrentAttributes
     attribute :world, :account, :person, :request
     delegate :time_zone, to: :person
 
-    resets { Time.zone = "UTC" }
+    before_reset { Session.previous = person.try(:id) }
+
+    resets do
+      Time.zone = "UTC"
+      Session.current = nil
+    end
 
     def account=(account)
       super
@@ -19,6 +24,7 @@ class CurrentAttributesTest < ActiveSupport::TestCase
     def person=(person)
       super
       Time.zone = person.try(:time_zone)
+      Session.current = person.try(:id)
     end
 
     def request
@@ -30,9 +36,14 @@ class CurrentAttributesTest < ActiveSupport::TestCase
     end
   end
 
+  class Session < ActiveSupport::CurrentAttributes
+    attribute :current, :previous
+  end
+
   setup do
     @original_time_zone = Time.zone
     Current.reset
+    Session.reset
   end
 
   teardown do
@@ -56,16 +67,28 @@ class CurrentAttributesTest < ActiveSupport::TestCase
   end
 
   test "set auxiliary class via overwritten method" do
-    Current.person = Person.new("David", "Central Time (US & Canada)")
+    Current.person = Person.new(42, "David", "Central Time (US & Canada)")
     assert_equal "Central Time (US & Canada)", Time.zone.name
+    assert_equal 42, Session.current
   end
 
-  test "resets auxiliary class via callback" do
-    Current.person = Person.new("David", "Central Time (US & Canada)")
+  test "resets auxiliary classes via callback" do
+    Current.person = Person.new(42, "David", "Central Time (US & Canada)")
     assert_equal "Central Time (US & Canada)", Time.zone.name
 
     Current.reset
     assert_equal "UTC", Time.zone.name
+    assert_nil Session.current
+  end
+
+  test "set auxiliary class based on current attributes via before callback" do
+    Current.person = Person.new(42, "David", "Central Time (US & Canada)")
+    assert_nil Session.previous
+    assert_equal 42, Session.current
+
+    Current.reset
+    assert_equal 42, Session.previous
+    assert_nil Session.current
   end
 
   test "set attribute only via scope" do
@@ -92,13 +115,13 @@ class CurrentAttributesTest < ActiveSupport::TestCase
   end
 
   test "delegation" do
-    Current.person = Person.new("David", "Central Time (US & Canada)")
+    Current.person = Person.new(42, "David", "Central Time (US & Canada)")
     assert_equal "Central Time (US & Canada)", Current.time_zone
     assert_equal "Central Time (US & Canada)", Current.instance.time_zone
   end
 
   test "all methods forward to the instance" do
-    Current.person = Person.new("David", "Central Time (US & Canada)")
+    Current.person = Person.new(42, "David", "Central Time (US & Canada)")
     assert_equal "David, in Central Time (US & Canada)", Current.intro
     assert_equal "David, in Central Time (US & Canada)", Current.instance.intro
   end