Fix strict loading on validations

We don't want strict loading to throw an error on validations since
those need to load the record in order to validate it.

This change check the owners's `validation_context`. If it's `nil` then
we know we're not currently validating an object in create/update. If
it's set then we're validating and want to skip raising for strict
loading.

Fixes: #40767

activerecord/lib/active_record/associations/association.rb

@@ -211,11 +211,11 @@ module ActiveRecord
 
       private
         def find_target
-          if owner.strict_loading?
+          if owner.strict_loading? && owner.validation_context.nil?
             Base.strict_loading_violation!(owner: owner.class, association: klass)
           end
 
-          if reflection.strict_loading?
+          if reflection.strict_loading? && owner.validation_context.nil?
             Base.strict_loading_violation!(owner: owner.class, association: reflection.name)
           end
 

activerecord/test/cases/strict_loading_test.rb

@@ -86,6 +86,27 @@ class StrictLoadingTest < ActiveRecord::TestCase
     end
   end
 
+  def test_strict_loading_is_ignored_in_validation_context
+    with_strict_loading_by_default(Developer) do
+      developer = Developer.first
+      assert_predicate developer, :strict_loading?
+
+      assert_nothing_raised do
+        AuditLogRequired.create! developer_id: developer.id, message: "i am a message"
+      end
+    end
+  end
+
+  def test_strict_loading_with_reflection_is_ignored_in_validation_context
+    with_strict_loading_by_default(Developer) do
+      developer = Developer.first
+      assert_predicate developer, :strict_loading?
+
+      developer.required_audit_logs.build(message: "I am message")
+      developer.save!
+    end
+  end
+
   def test_preload_audit_logs_are_strict_loading_because_parent_is_strict_loading
     developer = Developer.first
 

activerecord/test/models/developer.rb

@@ -72,6 +72,7 @@ class Developer < ActiveRecord::Base
                           class_name: "SpecialProject"
 
   has_many :audit_logs
+  has_many :required_audit_logs, class_name: "AuditLogRequired"
   has_many :strict_loading_audit_logs, -> { strict_loading }, class_name: "AuditLog"
   has_many :strict_loading_opt_audit_logs, strict_loading: true, class_name: "AuditLog"
   has_many :contracts
@@ -125,6 +126,11 @@ class AuditLog < ActiveRecord::Base
   belongs_to :unvalidated_developer, class_name: "Developer"
 end
 
+class AuditLogRequired < ActiveRecord::Base
+  self.table_name = "audit_logs"
+  belongs_to :developer, required: true
+end
+
 class DeveloperWithBeforeDestroyRaise < ActiveRecord::Base
   self.table_name = "developers"
   has_and_belongs_to_many :projects, join_table: "developers_projects", foreign_key: "developer_id"