Fix buffer property is not ArrayBuffer issue.

e2e/__tests__/env.test.js

@@ -14,25 +14,37 @@ const getLog = result => result.stdout.split('\n')[1].trim();
 
 describe('Environment override', () => {
   it('uses jsdom when specified', () => {
-    const result = runJest('env-test', ['--env=jsdom']);
+    const result = runJest('env-test', ['--env=jsdom', 'env.test.js']);
     expect(result.status).toBe(0);
     expect(getLog(result)).toBe('WINDOW');
   });
 
   it('uses node as default from package.json', () => {
-    const result = runJest('env-test');
+    const result = runJest('env-test', ['env.test.js']);
     expect(result.status).toBe(0);
     expect(getLog(result)).toBe('NO WINDOW');
   });
 
   it('uses node when specified', () => {
-    const result = runJest('env-test', ['--env=node']);
+    const result = runJest('env-test', ['--env=node', 'env.test.js']);
     expect(result.status).toBe(0);
     expect(getLog(result)).toBe('NO WINDOW');
   });
 
   it('fails when the env is not available', () => {
-    const result = runJest('env-test', ['--env=banana']);
+    const result = runJest('env-test', ['--env=banana', 'env.test.js']);
     expect(result.status).toBe(1);
   });
 });
+
+describe('Environment equivalent', () => {
+  it('uses jsdom', () => {
+    const result = runJest('env-test', ['--env=jsdom', 'equivalent.test.js']);
+    expect(result.status).toBe(0);
+  });
+
+  it('uses node', () => {
+    const result = runJest('env-test', ['--env=node', 'equivalent.test.js']);
+    expect(result.status).toBe(0);
+  });
+});

e2e/env-test/__tests__/equivalent.test.js

@@ -0,0 +1,14 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+'use strict';
+
+test('Buffer', () => {
+  const bufFromArray = Buffer.from([0x62, 0x75, 0x66, 0x66, 0x65, 0x72]);
+  expect(bufFromArray.buffer instanceof ArrayBuffer).toBeTruthy();
+  const bufFromArrayBuffer = Buffer.from(new ArrayBuffer(6));
+  expect(bufFromArrayBuffer.buffer instanceof ArrayBuffer).toBeTruthy();
+});

packages/jest-environment-node/src/index.js

@@ -39,6 +39,7 @@ class NodeEnvironment {
     global.clearTimeout = clearTimeout;
     global.setInterval = setInterval;
     global.setTimeout = setTimeout;
+    global.ArrayBuffer = ArrayBuffer;
     // URL and URLSearchParams are global in Node >= 10
     if (typeof URL !== 'undefined' && typeof URLSearchParams !== 'undefined') {
       /* global URL, URLSearchParams */