Merge branch 'xanf-refactor-global-toast' into 'master'

Refactor global_toast to avoid instance export

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/114071



Merged-by: Natalia Tepluhina <ntepluhina@gitlab.com>
Approved-by: Tomas Bulva <tbulva@gitlab.com>
Approved-by: Natalia Tepluhina <ntepluhina@gitlab.com>
Co-authored-by: Illya Klymov <xanf@xanf.me>

app/assets/javascripts/vue_shared/plugins/global_toast.js

@@ -2,7 +2,7 @@ import { GlToast } from '@gitlab/ui';
 import Vue from 'vue';
 
 Vue.use(GlToast);
-export const instance = new Vue();
+const instance = new Vue();
 
 export default function showGlobalToast(...args) {
   return instance.$toast.show(...args);

spec/frontend/vue_shared/plugins/global_toast_spec.js

-import toast, { instance } from '~/vue_shared/plugins/global_toast';
+import toast from '~/vue_shared/plugins/global_toast';
 
-describe('Global toast', () => {
-  let spyFunc;
-
-  beforeEach(() => {
-    spyFunc = jest.spyOn(instance.$toast, 'show').mockImplementation(() => {});
-  });
+const mockSpy = jest.fn();
+jest.mock('@gitlab/ui', () => ({
+  GlToast: (Vue) => {
+    // eslint-disable-next-line no-param-reassign
+    Vue.prototype.$toast = { show: (...args) => mockSpy(...args) };
+  },
+}));
 
+describe('Global toast', () => {
   afterEach(() => {
-    spyFunc.mockRestore();
+    mockSpy.mockRestore();
   });
 
   it("should call GitLab UI's toast method", () => {
@@ -17,7 +19,7 @@ describe('Global toast', () => {
 
     toast(arg1, arg2);
 
-    expect(instance.$toast.show).toHaveBeenCalledTimes(1);
-    expect(instance.$toast.show).toHaveBeenCalledWith(arg1, arg2);
+    expect(mockSpy).toHaveBeenCalledTimes(1);
+    expect(mockSpy).toHaveBeenCalledWith(arg1, arg2);
   });
 });