Ensure Contextual validations fire on associations

If a custom validation context is used, the validations on dependent
association records should fire regardless of whether those record have
`changed_for_autosave?` or not as the use of a custom validation context
increases the chance that validations for the context will be different
to those from when the record was first saved.

6ea80b6 changed the autosave behaviour for single associations such that
validations would only fire on an associated record if the record was
`changed_for_autosave?`. This brought the behaviour inline with that for
collection associations, but introduce a regression in that validations
would no longer fire on dependent associations, even when using a custom
validation context.

This change updates the behaviour for both single and collection
associations.

This commit also updates another related regression test that became a
potential false-positive when 6ea80b6 was merged. The original test was
written to protect against non-custom validations firing on associations
(see #14106). At the time validations on autosaving singular
associations would always fire, even when the association was not dirty,
whereas after 6ea80b6 the validations only fire if the association is
dirty. This update to the test makes the association record dirty to
ensure the validations will fire so that the code responsible for
excluding non-custom contexts is correctly exercised.

activerecord/lib/active_record/autosave_association.rb

@@ -270,7 +270,7 @@ def changed_for_autosave?
       # or saved. If +autosave+ is +false+ only new records will be returned,
       # unless the parent is/was a new record itself.
       def associated_records_to_validate_or_save(association, new_record, autosave)
-        if new_record
+        if new_record || custom_validation_context?
           association && association.target
         elsif autosave
           association.target.find_all(&:changed_for_autosave?)
@@ -302,7 +302,7 @@ def nested_records_changed_for_autosave?
       def validate_single_association(reflection)
         association = association_instance_get(reflection.name)
         record      = association && association.reader
-        association_valid?(reflection, record) if record && record.changed_for_autosave?
+        association_valid?(reflection, record) if record && (record.changed_for_autosave? || custom_validation_context?)
       end
 
       # Validate the associated records if <tt>:validate</tt> or
@@ -322,7 +322,7 @@ def validate_collection_association(reflection)
       def association_valid?(reflection, record, index = nil)
         return true if record.destroyed? || (reflection.options[:autosave] && record.marked_for_destruction?)
 
-        context = validation_context unless [:create, :update].include?(validation_context)
+        context = validation_context if custom_validation_context?
 
         unless valid = record.valid?(context)
           if reflection.options[:autosave]
@@ -492,6 +492,10 @@ def save_belongs_to_association(reflection)
         end
       end
 
+      def custom_validation_context?
+        validation_context && [:create, :update].exclude?(validation_context)
+      end
+
       def _ensure_no_duplicate_errors
         errors.uniq!
       end

activerecord/test/cases/autosave_association_test.rb

@@ -35,7 +35,7 @@
 require "models/reply"
 
 class TestAutosaveAssociationsInGeneral < ActiveRecord::TestCase
-  def test_autosave_validation
+  def test_autosave_does_not_pass_through_non_custom_validation_contexts
     person = Class.new(ActiveRecord::Base) {
       self.table_name = "people"
       validate :should_be_cool, on: :create
@@ -55,8 +55,11 @@ def self.name; "Reference"; end
     }
 
     u = person.create!(first_name: "cool")
-    u.update!(first_name: "nah") # still valid because validation only applies on 'create'
-    assert_predicate reference.create!(person: u), :persisted?
+    u.first_name = "nah"
+
+    assert_predicate u, :valid?
+    r = reference.new(person: u)
+    assert_predicate r, :valid?
   end
 
   def test_should_not_add_the_same_callbacks_multiple_times_for_has_one
@@ -1736,6 +1739,14 @@ def setup
     assert_equal(author_count_before_save, Author.count)
     assert_equal(book_count_before_save, Book.count)
   end
+
+  def test_validations_still_fire_on_unchanged_association_with_custom_validation_context
+    pirate = FamousPirate.create!(catchphrase: "Avast Ye!")
+    pirate.famous_ships.create!
+
+    assert pirate.valid?
+    assert_not pirate.valid?(:conference)
+  end
 end
 
 class TestAutosaveAssociationValidationsOnAHasOneAssociation < ActiveRecord::TestCase
@@ -1780,6 +1791,13 @@ def setup
     @pirate.non_validated_parrot = Parrot.new(name: "")
     assert_predicate @pirate, :valid?
   end
+
+  def test_validations_still_fire_on_unchanged_association_with_custom_validation_context
+    firm_with_low_credit = Firm.create!(name: "Something", account: Account.new(credit_limit: 50))
+
+    assert firm_with_low_credit.valid?
+    assert_not firm_with_low_credit.valid?(:bank_loan)
+  end
 end
 
 class TestAutosaveAssociationValidationsOnAHABTMAssociation < ActiveRecord::TestCase

activerecord/test/models/account.rb

@@ -21,12 +21,17 @@ def self.destroyed_account_ids
   end
 
   validate :check_empty_credit_limit
+  validate :ensure_good_credit, on: :bank_loan
 
   private
     def check_empty_credit_limit
       errors.add("credit_limit", :blank) if credit_limit.blank?
     end
 
+    def ensure_good_credit
+      errors.add(:credit_limit, "too low") unless credit_limit > 10_000
+    end
+
     def private_method
       "Sir, yes sir!"
     end

activerecord/test/models/pirate.rb

@@ -95,7 +95,7 @@ class DestructivePirate < Pirate
 
 class FamousPirate < ActiveRecord::Base
   self.table_name = "pirates"
-  has_many :famous_ships
+  has_many :famous_ships, inverse_of: :famous_pirate, foreign_key: :pirate_id
   validates_presence_of :catchphrase, on: :conference
 end
 

activerecord/test/models/ship.rb

@@ -37,6 +37,6 @@ class Prisoner < ActiveRecord::Base
 
 class FamousShip < ActiveRecord::Base
   self.table_name = "ships"
-  belongs_to :famous_pirate
+  belongs_to :famous_pirate, foreign_key: :pirate_id
   validates_presence_of :name, on: :conference
 end