[test] Karma should fail if errors are thrown (#543)

test/karma.conf.js

@@ -54,8 +54,9 @@ module.exports = function setKarmaConfig(config) {
       plugins: [
         new webpack.DefinePlugin({
           'process.env': {
-            NODE_ENV: JSON.stringify('test'),
+            NODE_ENV: '"test"',
             CI: JSON.stringify(process.env.CI),
+            KARMA: 'true',
           },
         }),
       ],

test/karma.tests.js

@@ -1,7 +1,55 @@
+/* eslint-env mocha */
 import './utils/init';
-import consoleError from './utils/consoleError';
+import { createMochaHooks } from '@material-ui/monorepo/test/utils/mochaHooks';
 
-consoleError();
+const mochaHooks = createMochaHooks(window.Mocha);
+
+before(function beforeAllHook() {
+  mochaHooks.beforeAll.forEach((mochaHook) => {
+    mochaHook.call(this);
+  });
+});
+
+after(function afterAllHook() {
+  mochaHooks.afterAll.forEach((mochaHook) => {
+    mochaHook.call(this);
+  });
+});
+
+beforeEach(function beforeEachHook() {
+  mochaHooks.beforeEach.forEach((mochaHook) => {
+    mochaHook.call(this);
+  });
+});
+
+afterEach(function afterEachHook() {
+  mochaHooks.afterEach.forEach((mochaHook) => {
+    mochaHook.call(this);
+  });
+});
+
+// Ensure that uncaught exceptions between tests result in the tests failing.
+// This works around an issue with mocha / karma-mocha, see
+// https://github.com/karma-runner/karma-mocha/issues/227
+let pendingError = null;
+let pendingErrorNotice = null;
+
+window.addEventListener('error', (event) => {
+  pendingError = event.error;
+  pendingErrorNotice = 'An uncaught exception was thrown between tests';
+});
+
+window.addEventListener('unhandledrejection', (event) => {
+  pendingError = event.reason;
+  pendingErrorNotice = 'An uncaught promise rejection occurred between tests';
+});
+
+afterEach(() => {
+  if (pendingError) {
+    console.error(pendingErrorNotice);
+    throw pendingError;
+  }
+});
 
 const packagesContext = require.context('../packages', true, /\.test\.tsx$/);
 packagesContext.keys().forEach(packagesContext);

yarn.lock

@@ -2735,8 +2735,8 @@
   resolved "https://github.com/mui-org/material-ui.git#41898e1318b0315e5a61e2df7780b6019f3b44f6"
 
 "@material-ui/monorepo@https://github.com/mui-org/material-ui.git#next":
-  version "5.0.0-alpha.13"
-  resolved "https://github.com/mui-org/material-ui.git#13f3e9d8db81b40e1b08f43e4d45e37f3926c37d"
+  version "5.0.0-alpha.15"
+  resolved "https://github.com/mui-org/material-ui.git#c500fc3faf873142b9124319cebf728dd9a12cc5"
 
 "@material-ui/styles@^4.10.0":
   version "4.10.0"