Remove babel-plugin-rewire dependency

This is a follow-up to [removing most no-op default exports][1]. In that
MR, the "most" was due to the fact that a couple of files were still
participating in Karma tests.

Since it turns out that no Karma tests rely on `babel-plugin-rewire`,
that could be removed, allowing the final two instances of workarounds
for it to be removed as well.

Finally, the `spyOnDependency` helper was removed, since it's unused.

[1]: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/37213

app/assets/javascripts/monitoring/stores/actions.js

@@ -506,6 +506,3 @@ export const fetchVariableMetricLabelValues = ({ state, commit }, { defaultQuery
 
   return Promise.all(optionsRequests);
 };
-
-// prevent babel-plugin-rewire from generating an invalid default during karma tests
-export default () => {};

app/assets/javascripts/monitoring/stores/getters.js

@@ -170,6 +170,3 @@ export const getCustomVariablesParams = state =>
  */
 export const fullDashboardPath = state =>
   normalizeCustomDashboardPath(state.currentDashboard, state.customDashboardBasePath);
-
-// prevent babel-plugin-rewire from generating an invalid default during karma tests
-export default () => {};

babel.config.js

@@ -35,11 +35,6 @@ if (BABEL_ENV === 'coverage') {
   ]);
 }
 
-// add rewire support when running tests
-if (BABEL_ENV === 'karma' || BABEL_ENV === 'coverage') {
-  plugins.push('babel-plugin-rewire');
-}
-
 // Jest is running in node environment, so we need additional plugins
 const isJest = Boolean(process.env.JEST_WORKER_ID);
 if (isJest) {

ee/app/assets/javascripts/epic/utils/epic_utils.js

@@ -92,11 +92,6 @@ const getDateFromMilestonesTooltip = ({
   );
 };
 
-// This is for mocking methods from this
-// file within tests using `spyOnDependency`
-// which requires first param to always
-// be default export of dependency as per
-// https://gitlab.com/help/development/testing_guide/frontend_testing.md#stubbing-and-mocking
 const epicUtils = {
   gqClient,
   triggerDocumentEvent,

package.json

@@ -166,7 +166,6 @@
     "babel-jest": "^24.1.0",
     "babel-plugin-dynamic-import-node": "^2.2.0",
     "babel-plugin-istanbul": "^5.1.0",
-    "babel-plugin-rewire": "^1.2.0",
     "chalk": "^2.4.1",
     "commander": "^2.18.0",
     "custom-jquery-matchers": "^2.1.0",

spec/javascripts/test_bundle.js

 /* eslint-disable
-  jasmine/no-global-setup, jasmine/no-unsafe-spy, no-underscore-dangle, no-console
+  jasmine/no-global-setup, no-underscore-dangle, no-console
 */
 
 import $ from 'jquery';
@@ -81,17 +81,6 @@ window.addEventListener('unhandledrejection', event => {
   console.error(event.reason.stack || event.reason);
 });
 
-// Add global function to spy on a module's dependencies via rewire
-window.spyOnDependency = (module, name) => {
-  const dependency = module.__GetDependency__(name);
-  const spy = jasmine.createSpy(name, dependency);
-  module.__Rewire__(name, spy);
-  return spy;
-};
-
-// Reset any rewired modules after each test (see babel-plugin-rewire)
-afterEach(__rewire_reset_all__); // eslint-disable-line
-
 // HACK: Chrome 59 disconnects if there are too many synchronous tests in a row
 // because it appears to lock up the thread that communicates to Karma's socket
 // This async beforeEach gets called on every spec and releases the JS thread long

yarn.lock

@@ -2156,11 +2156,6 @@ babel-plugin-lodash@^3.3.4:
     lodash "^4.17.10"
     require-package-name "^2.0.1"
 
-babel-plugin-rewire@^1.2.0:
-  version "1.2.0"
-  resolved "https://registry.yarnpkg.com/babel-plugin-rewire/-/babel-plugin-rewire-1.2.0.tgz#822562d72ed2c84e47c0f95ee232c920853e9d89"
-  integrity sha512-JBZxczHw3tScS+djy6JPLMjblchGhLI89ep15H3SyjujIzlxo5nr6Yjo7AXotdeVczeBmWs0tF8PgJWDdgzAkQ==
-
 babel-preset-jest@^24.6.0:
   version "24.6.0"
   resolved "https://registry.yarnpkg.com/babel-preset-jest/-/babel-preset-jest-24.6.0.tgz#66f06136eefce87797539c0d63f1769cc3915984"