Add tests for health controller

test/music_library_web/controllers/health_controller_test.exs

@@ -0,0 +1,12 @@
+defmodule MusicLibraryWeb.HealthControllerTest do
+  use MusicLibraryWeb.ConnCase
+
+  describe "GET /health" do
+    @tag :logged_out
+    test "returns 200 with health message", %{conn: conn} do
+      conn = get(conn, "/health")
+
+      assert html_response(conn, 200) =~ "App is running"
+    end
+  end
+end