fix(esm): allow import from mocha in parallel

lib/mocha.js

@@ -96,6 +96,53 @@ exports.Suite = Suite;
 exports.Hook = require('./hook');
 exports.Test = require('./test');
 
+let currentContext;
+exports.afterEach = function(...args) {
+  (currentContext.afterEach || currentContext.teardown).apply(this, args);
+};
+exports.after = function(...args) {
+  (currentContext.after || currentContext.suiteTeardown).apply(this, args);
+};
+exports.beforeEach = function(...args) {
+  (currentContext.beforeEach || currentContext.setup).apply(this, args);
+};
+exports.before = function(...args) {
+  (currentContext.before || currentContext.suiteSetup).apply(this, args);
+};
+exports.describe = function(...args) {
+  (currentContext.describe || currentContext.suite).apply(this, args);
+};
+exports.it = function(...args) {
+  (currentContext.it || currentContext.test).apply(this, args);
+};
+exports.xit = function(...args) {
+  (
+    currentContext.xit ||
+    (currentContext.test && currentContext.test.skip)
+  ).apply(this, args);
+};
+exports.setup = function(...args) {
+  (currentContext.setup || currentContext.beforeEach).apply(this, args);
+};
+exports.suiteSetup = function(...args) {
+  (currentContext.suiteSetup || currentContext.before).apply(this, args);
+};
+exports.suiteTeardown = function(...args) {
+  (currentContext.suiteTeardown || currentContext.after).apply(this, args);
+};
+exports.suite = function(...args) {
+  (currentContext.suite || currentContext.describe).apply(this, args);
+};
+exports.teardown = function(...args) {
+  (currentContext.teardown || currentContext.afterEach).apply(this, args);
+};
+exports.test = function(...args) {
+  (currentContext.test || currentContext.it).apply(this, args);
+};
+exports.run = function(...args) {
+  currentContext.run.apply(this, args);
+};
+
 /**
  * Constructs a new Mocha instance with `options`.
  *
@@ -351,20 +398,7 @@ Mocha.prototype.ui = function(ui) {
   bindInterface(this.suite);
 
   this.suite.on(EVENT_FILE_PRE_REQUIRE, function(context) {
-    exports.afterEach = context.afterEach || context.teardown;
-    exports.after = context.after || context.suiteTeardown;
-    exports.beforeEach = context.beforeEach || context.setup;
-    exports.before = context.before || context.suiteSetup;
-    exports.describe = context.describe || context.suite;
-    exports.it = context.it || context.test;
-    exports.xit = context.xit || (context.test && context.test.skip);
-    exports.setup = context.setup || context.beforeEach;
-    exports.suiteSetup = context.suiteSetup || context.before;
-    exports.suiteTeardown = context.suiteTeardown || context.after;
-    exports.suite = context.suite || context.describe;
-    exports.teardown = context.teardown || context.afterEach;
-    exports.test = context.test || context.it;
-    exports.run = context.run;
+    currentContext = context;
   });
 
   return this;
@@ -1299,7 +1333,7 @@ Mocha.prototype.hasGlobalTeardownFixtures = function hasGlobalTeardownFixtures()
  * A (sync) function to assert a user-supplied plugin implementation is valid.
  *
  * Defined in a {@link PluginDefinition}.
- 
+
  * @callback PluginValidator
  * @param {*} value - Value to check
  * @this {PluginDefinition}

test/integration/fixtures/parallel/test1.mjs

@@ -0,0 +1,5 @@
+import {describe,it} from "../../../../index.js";
+
+describe('test1', () => {
+  it('should pass', () => {});
+});

test/integration/fixtures/parallel/test2.mjs

@@ -0,0 +1,5 @@
+import {describe,it} from "../../../../index.js";
+
+describe('test2', () => {
+  it('should pass', () => {});
+});

test/integration/fixtures/parallel/test3.mjs

@@ -0,0 +1,7 @@
+import {describe,it} from "../../../../index.js";
+
+describe('test3', () => {
+  it('should fail', () => {
+    throw new Error('expecting this error to fail');
+  });
+});

test/integration/parallel.spec.js

@@ -0,0 +1,28 @@
+'use strict';
+
+const assert = require('assert');
+const {runMochaJSONAsync} = require('./helpers');
+const semver = require('semver');
+
+describe('parallel run', () => {
+  /**
+   * @see https://github.com/mochajs/mocha/issues/4559
+   */
+  it('should allow `import {it} from "mocha"` module syntax', async () => {
+    if (semver.major(process.version) <= 10) {
+      console.log(
+        `[SKIPPED] for node ${process.version} (es module syntax isn't supported on node <= 10)`
+      );
+    } else {
+      const result = await runMochaJSONAsync('parallel/test3.mjs', [
+        '--parallel',
+        '--jobs',
+        '2',
+        require.resolve('./fixtures/parallel/test1.mjs'),
+        require.resolve('./fixtures/parallel/test2.mjs')
+      ]);
+      assert.strictEqual(result.stats.failures, 1);
+      assert.strictEqual(result.stats.passes, 2);
+    }
+  });
+});