Provide a better error message on :required association

Fixes #18696.

2 files changed, 23 insertions, 3 deletions

diff --git a/activerecord/lib/active_record/associations/builder/singular_association.rb b/activerecord/lib/active_record/associations/builder/singular_association.rb
index 1369212837..f6274c027e 100644
--- a/activerecord/lib/active_record/associations/builder/singular_association.rb
+++ b/activerecord/lib/active_record/associations/builder/singular_association.rb
@@ -31,7 +31,7 @@ module ActiveRecord::Associations::Builder
     def self.define_validations(model, reflection)
       super
       if reflection.options[:required]
-        model.validates_presence_of reflection.name
+        model.validates_presence_of reflection.name, message: :required
       end
     end
   end
diff --git a/activerecord/test/cases/associations/required_test.rb b/activerecord/test/cases/associations/required_test.rb
index a6123ac432..8b765a2e0c 100644
--- a/activerecord/test/cases/associations/required_test.rb
+++ b/activerecord/test/cases/associations/required_test.rb
@@ -40,7 +40,7 @@ class RequiredAssociationsTest < ActiveRecord::TestCase
 
     record = model.new
     assert_not record.save
-    assert_equal ["Parent can't be blank"], record.errors.full_messages
+    assert_equal ["Parent must exist"], record.errors.full_messages
 
     record.parent = Parent.new
     assert record.save
@@ -64,12 +64,32 @@ class RequiredAssociationsTest < ActiveRecord::TestCase
 
     record = model.new
     assert_not record.save
-    assert_equal ["Child can't be blank"], record.errors.full_messages
+    assert_equal ["Child must exist"], record.errors.full_messages
 
     record.child = Child.new
     assert record.save
   end
 
+  test "required has_one associations have a correct error message" do
+    model = subclass_of(Parent) do
+      has_one :child, required: true, inverse_of: false,
+      class_name: "RequiredAssociationsTest::Child"
+    end
+
+    record = model.create
+    assert_equal ["Child must exist"], record.errors.full_messages
+  end
+
+  test "required belongs_to associations have a correct error message" do
+    model = subclass_of(Child) do
+      belongs_to :parent, required: true, inverse_of: false,
+      class_name: "RequiredAssociationsTest::Parent"
+    end
+
+    record = model.create
+    assert_equal ["Parent must exist"], record.errors.full_messages
+  end
+
   private
 
   def subclass_of(klass, &block)