Merge pull request #85 from dollarshaveclub/realm-comparison

Better support for comparisons and instanceof

Author: hankjacobs

jest-env.js

@@ -1,4 +1,5 @@
 const runtime = require('../runtime')
+const vm = require('vm')
 
 describe('runtime', () => {
   test('context allows overriding of properties via bindings', async () => {
@@ -32,10 +33,37 @@ describe('runtime', () => {
       'TextEncoder',
       'atob',
       'btoa',
+      'ArrayBuffer',
+      'Int8Array',
+      'Uint8Array',
+      'Uint8ClampedArray',
+      'Int16Array',
+      'Uint16Array',
+      'Int32Array',
+      'Uint32Array',
+      'Float32Array',
+      'Float64Array',
+      'Object',
+      'constructor',
     ].sort()
 
     const dummyFactory = Symbol('dummy factory')
     const got = Object.getOwnPropertyNames(new runtime.Context(() => {}, dummyFactory)).sort()
     expect(got).toEqual(expected)
   })
+
+  test('instanceof from different realm works', () => {
+    const dummyFactory = Symbol('dummy factory')
+    const bindings = {
+      instanceOfObject: (obj) => { return obj instanceof Object },
+      isArrayBufferView: (ab) => { return ArrayBuffer.isView(ab) },
+    }
+    const context = new runtime.Context(() => {}, dummyFactory, bindings)
+
+    const objTest = vm.runInNewContext('instanceOfObject(new Object())', context)
+    const arrayBufferViewTest = vm.runInNewContext('isArrayBufferView(new Uint16Array())', context)
+
+    expect(objTest).toEqual(true)
+    expect(arrayBufferViewTest).toEqual(true)
+  })
 })

lib/__tests__/runtime.test.js

@@ -30,6 +30,21 @@ class Context {
     this.TextEncoder = TextEncoder
     this.atob = atob
     this.btoa = btoa
+
+    // These are necessary to use "instanceof" within a vm
+    this.ArrayBuffer = ArrayBuffer
+    this.Int8Array = Int8Array
+    this.Uint8Array = Uint8Array
+    this.Uint8ClampedArray = Uint8ClampedArray
+    this.Int16Array = Int16Array
+    this.Uint16Array = Uint16Array
+    this.Int32Array = Int32Array
+    this.Uint32Array = Uint32Array
+    this.Float32Array = Float32Array
+    this.Float64Array = Float64Array
+    this.Object = Object
+    this.constructor = constructor
+
     Object.assign(this, bindings)
   }
 }

lib/runtime.js

@@ -57,7 +57,7 @@
     "typescript": "^3.2.2"
   },
   "jest": {
-    "testEnvironment": "./jest-env",
+    "testEnvironment": "node",
     "automock": false,
     "setupTestFrameworkScriptFile": "./jest-setup-framework.js",
     "testPathIgnorePatterns": [