[Validator] Handle edge case for has_one_attached (#193)

lib/active_storage_validations/shared/asv_attachable.rb

@@ -24,21 +24,28 @@ def validate_changed_files_from_metadata(record, attribute, metadata_keys)
 
     # Retrieve an array-like of attachables and blobs. Unlike its name suggests,
     # getting attachables from attachment_changes is not getting the changed
-    # attachables but all attachables from the has_many_attached relation.
+    # attachables but all attachables from the `has_many_attached` relation.
+    # For the `has_one_attached` relation, it only yields the new attachable,
+    # but if we are validating previously attached file, we need to use the blob
     # See #attach at: https://github.com/rails/rails/blob/main/activestorage/lib/active_storage/attached/many.rb
     #
     # Some file could be passed several times, we just need to perform the
     # analysis once on the file, therefore the use of #uniq.
     def attachables_and_blobs(record, attribute)
-      changes = record.attachment_changes[attribute.to_s]
+      changes = if record.public_send(attribute).is_a?(ActiveStorage::Attached::One)
+        record.attachment_changes[attribute.to_s].presence || record.public_send(attribute)
+      else
+        record.attachment_changes[attribute.to_s]
+      end
+
       return to_enum(:attachables_and_blobs, record, attribute) if changes.blank? || !block_given?
 
       if changes.is_a?(ActiveStorage::Attached::Changes::CreateMany)
         changes.attachables.uniq.zip(changes.blobs.uniq).each do |attachable, blob|
           yield attachable, blob
         end
       else
-        yield changes.attachable, changes.blob
+        yield changes.is_a?(ActiveStorage::Attached::Changes::CreateOne) ? changes.attachable : changes.blob, changes.blob
       end
     end
 

test/validators/shared_examples/works_fine_with_attachables.rb

@@ -284,6 +284,23 @@ def fixture_file_upload(filename, mime_type = nil, binary = false)
         end
       end
 
+      describe "when an invalid file has been attached on a `has_one_attached` relation without validation" do
+        before do
+          subject.using_attachable.attach(attachable_not_passing_validations)
+          subject.save(validate: false)
+        end
+
+        let(:attachable_not_passing_validations) do
+          tar_file_with_image_content_type
+        end
+
+        describe "when we try to validate the record afterwards" do
+          it "is invalid" do
+            assert_equal false, subject.valid?
+          end
+        end
+      end
+
       describe "when using `file_fixture_upload` (or its alias `fixture_file_upload`)" do
         let(:attachable) { fixture_file_upload('image_150x150.png', 'image/png') }