Implement Instance Moderation Notes (#31529)

spec/models/instance_moderation_note_spec.rb

@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe InstanceModerationNote do
+  describe 'chronological' do
+    it 'returns the instance notes sorted by oldest first' do
+      instance = Instance.find_or_initialize_by(domain: TagManager.instance.normalize_domain('mastodon.example'))
+
+      note1 = Fabricate(:instance_moderation_note, domain: instance.domain)
+      note2 = Fabricate(:instance_moderation_note, domain: instance.domain)
+
+      expect(instance.moderation_notes.chronological).to eq [note1, note2]
+    end
+  end
+
+  describe 'validations' do
+    it 'is invalid if the content is empty' do
+      note = Fabricate.build(:instance_moderation_note, domain: 'mastodon.example', content: '')
+      expect(note.valid?).to be false
+    end
+
+    it 'is invalid if content is longer than character limit' do
+      note = Fabricate.build(:instance_moderation_note, domain: 'mastodon.example', content: comment_over_limit)
+      expect(note.valid?).to be false
+    end
+
+    it 'is valid even if the instance does not exist yet' do
+      note = Fabricate.build(:instance_moderation_note, domain: 'non-existent.example', content: 'test comment')
+      expect(note.valid?).to be true
+    end
+
+    def comment_over_limit
+      Faker::Lorem.paragraph_by_chars(number: described_class::CONTENT_SIZE_LIMIT * 2)
+    end
+  end
+end