Fix monaco_loader_spec

spec/javascripts/repo/monaco_loader_spec.js

+/* global __webpack_public_path__ */
+import monacoContext from 'monaco-editor/dev/vs/loader';
+
 describe('MonacoLoader', () => {
-  it('sets __monaco_context__', () => {
-    const monacoContext = require('monaco-editor/dev/vs/loader'); // eslint-disable-line global-require
+  it('calls require.config and exports require', () => {
+    spyOn(monacoContext.require, 'config');
+
+    const monacoLoader = require('~/repo/monaco_loader'); // eslint-disable-line global-require
 
-    expect(window.__monaco_context__) // eslint-disable-line no-underscore-dangle
-      .toBe(monacoContext);
+    expect(monacoContext.require.config).toHaveBeenCalledWith({
+      paths: {
+        vs: `${__webpack_public_path__}monaco-editor/vs`, // eslint-disable-line camelcase
+      },
+    });
+    expect(monacoLoader.default).toBe(monacoContext.require);
   });
 });