DEV: Move discourse-chat to the core repo. (#18776)

As part of this move, we are also renaming `discourse-chat` to `chat`.

plugins/chat/spec/integration/plugin_api_spec.rb

@@ -0,0 +1,27 @@
+# frozen_string_literal: true
+
+require "rails_helper"
+
+describe "Plugin API for chat" do
+  before { SiteSetting.chat_enabled = true }
+
+  let(:metadata) do
+    metadata = Plugin::Metadata.new
+    metadata.name = "test"
+    metadata
+  end
+
+  let(:plugin_instance) do
+    plugin = Plugin::Instance.new(nil, "/tmp/test.rb")
+    plugin.metadata = metadata
+    plugin
+  end
+
+  describe "chat.enable_markdown_feature" do
+    it "stores the markdown feature" do
+      plugin_instance.chat.enable_markdown_feature(:foo)
+
+      expect(DiscoursePluginRegistry.chat_markdown_features.include?(:foo)).to be_truthy
+    end
+  end
+end