test: make sure to check global properties

Author: MatteoGabriele

src/index.test.ts

@@ -1,3 +1,5 @@
+import { createApp } from "vue";
+import * as api from "./api/index";
 import addGtag from "./core/add-gtag";
 import { createGtag } from "./index";
 
@@ -8,4 +10,13 @@ describe("index", () => {
     createGtag({ tagId: "UA-123456789" });
     expect(addGtag).toHaveBeenCalled();
   });
+
+  it("should install global properties", () => {
+    const app = createApp({});
+    const gtag = createGtag({ tagId: "UA-123456789" });
+
+    app.use(gtag);
+
+    expect(app.config.globalProperties.$gtag).toEqual(api);
+  });
 });