electron/spec-main/api-context-bridge-spec.ts

import { contextBridge, BrowserWindow, ipcMain } from 'electron'
import { expect } from 'chai'
import * as fs from 'fs-extra'
import * as os from 'os'
import * as path from 'path'

import { closeWindow } from './window-helpers'
import { emittedOnce } from './events-helpers'

const fixturesPath = path.resolve(__dirname, 'fixtures', 'api', 'context-bridge')

describe('contextBridge', () => {
  let w: BrowserWindow
  let dir: string

  afterEach(async () => {
    await closeWindow(w)
    if (dir) await fs.remove(dir)
  })

  it('should not be accessible when contextIsolation is disabled', async () => {
    w = new BrowserWindow({
      show: false,
      webPreferences: {
        contextIsolation: false,
        preload: path.resolve(fixturesPath, 'can-bind-preload.js')
      }
    })
    const [, bound] = await emittedOnce(ipcMain, 'context-bridge-bound', () => w.loadFile(path.resolve(fixturesPath, 'empty.html')))
    expect(bound).to.equal(false)
  })

  it('should be accessible when contextIsolation is enabled', async () => {
    w = new BrowserWindow({
      show: false,
      webPreferences: {
        contextIsolation: true,
        preload: path.resolve(fixturesPath, 'can-bind-preload.js')
      }
    })
    const [, bound] = await emittedOnce(ipcMain, 'context-bridge-bound', () => w.loadFile(path.resolve(fixturesPath, 'empty.html')))
    expect(bound).to.equal(true)
  })

  const generateTests = (useSandbox: boolean) => {
    describe(`with sandbox=${useSandbox}`, () => {
      const makeBindingWindow = async (bindingCreator: Function) => {
        const preloadContent = `const electron_1 = require('electron');
        ${useSandbox ? '' : `require('v8').setFlagsFromString('--expose_gc');
        const gc=require('vm').runInNewContext('gc');
        electron_1.contextBridge.exposeInMainWorld('GCRunner', {
          run: () => gc()
        });`}
        (${bindingCreator.toString()})();`
        const tmpDir = await fs.mkdtemp(path.resolve(os.tmpdir(), 'electron-spec-preload-'))
        dir = tmpDir
        await fs.writeFile(path.resolve(tmpDir, 'preload.js'), preloadContent)
        w = new BrowserWindow({
          show: false,
          webPreferences: {
            contextIsolation: true,
            nodeIntegration: true,
            sandbox: useSandbox,
            preload: path.resolve(tmpDir, 'preload.js')
          }
        })
        await w.loadFile(path.resolve(fixturesPath, 'empty.html'))
      }

      const callWithBindings = (fn: Function) =>
        w.webContents.executeJavaScript(`(${fn.toString()})(window)`)

      const getGCInfo = async (): Promise<{
        functionCount: number
        objectCount: number
        liveFromValues: number
        liveProxyValues: number
      }> => {
        const [, info] = await emittedOnce(ipcMain, 'gc-info', () => w.webContents.send('get-gc-info'))
        return info
      }

      it('should proxy numbers', async () => {
        await makeBindingWindow(() => {
          contextBridge.exposeInMainWorld('example', {
            myNumber: 123
          })
        })
        const result = await callWithBindings((root: any) => {
          return root.example.myNumber
        })
        expect(result).to.equal(123)
      })

      it('should make properties unwriteable', async () => {
        await makeBindingWindow(() => {
          contextBridge.exposeInMainWorld('example', {
            myNumber: 123
          })
        })
        const result = await callWithBindings((root: any) => {
          root.example.myNumber = 456
          return root.example.myNumber
        })
        expect(result).to.equal(123)
      })

      it('should proxy strings', async () => {
        await makeBindingWindow(() => {
          contextBridge.exposeInMainWorld('example', {
            myString: 'my-words'
          })
        })
        const result = await callWithBindings((root: any) => {
          return root.example.myString
        })
        expect(result).to.equal('my-words')
      })

      it('should proxy arrays', async () => {
        await makeBindingWindow(() => {
          contextBridge.exposeInMainWorld('example', {
            myArr: [123, 'my-words']
          })
        })
        const result = await callWithBindings((root: any) => {
          return root.example.myArr
        })
        expect(result).to.deep.equal([123, 'my-words'])
      })

      it('should make arrays immutable', async () => {
        await makeBindingWindow(() => {
          contextBridge.exposeInMainWorld('example', {
            myArr: [123, 'my-words']
          })
        })
        const immutable = await callWithBindings((root: any) => {
          try {
            root.example.myArr.push(456)
            return false
          } catch {
            return true
          }
        })
        expect(immutable).to.equal(true)
      })

      it('should proxy booleans', async () => {
        await makeBindingWindow(() => {
          contextBridge.exposeInMainWorld('example', {
            myBool: true
          })
        })
        const result = await callWithBindings((root: any) => {
          return root.example.myBool
        })
        expect(result).to.equal(true)
      })

      it('should proxy promises and resolve with the correct value', async () => {
        await makeBindingWindow(() => {
          contextBridge.exposeInMainWorld('example', {
            myPromise: Promise.resolve('i-resolved')
          })
        })
        const result = await callWithBindings((root: any) => {
          return root.example.myPromise
        })
        expect(result).to.equal('i-resolved')
      })

      it('should proxy promises and reject with the correct value', async () => {
        await makeBindingWindow(() => {
          contextBridge.exposeInMainWorld('example', {
            myPromise: Promise.reject(new Error('i-rejected'))
          })
        })
        const result = await callWithBindings(async (root: any) => {
          try {
            await root.example.myPromise
            return null
          } catch (err) {
            return err
          }
        })
        expect(result).to.be.an.instanceOf(Error).with.property('message', 'Uncaught Error: i-rejected')
      })

      it('should proxy promises and resolve with the correct value if it resolves later', async () => {
        await makeBindingWindow(() => {
          contextBridge.exposeInMainWorld('example', {
            myPromise: () => new Promise(resolve => setTimeout(() => resolve('delayed'), 20))
          })
        })
        const result = await callWithBindings((root: any) => {
          return root.example.myPromise()
        })
        expect(result).to.equal('delayed')
      })

      it('should proxy nested promises correctly', async () => {
        await makeBindingWindow(() => {
          contextBridge.exposeInMainWorld('example', {
            myPromise: () => new Promise(resolve => setTimeout(() => resolve(Promise.resolve(123)), 20))
          })
        })
        const result = await callWithBindings((root: any) => {
          return root.example.myPromise()
        })
        expect(result).to.equal(123)
      })

      it('should proxy methods', async () => {
        await makeBindingWindow(() => {
          contextBridge.exposeInMainWorld('example', {
            getNumber: () => 123,
            getString: () => 'help',
            getBoolean: () => false,
            getPromise: async () => 'promise'
          })
        })
        const result = await callWithBindings(async (root: any) => {
          return [root.example.getNumber(), root.example.getString(), root.example.getBoolean(), await root.example.getPromise()]
        })
        expect(result).to.deep.equal([123, 'help', false, 'promise'])
      })

      it('should proxy methods that are callable multiple times', async () => {
        await makeBindingWindow(() => {
          contextBridge.exposeInMainWorld('example', {
            doThing: () => 123
          })
        })
        const result = await callWithBindings(async (root: any) => {
          return [root.example.doThing(), root.example.doThing(), root.example.doThing()]
        })
        expect(result).to.deep.equal([123, 123, 123])
      })

      it('should proxy methods in the reverse direction', async () => {
        await makeBindingWindow(() => {
          contextBridge.exposeInMainWorld('example', {
            callWithNumber: (fn: any) => fn(123)
          })
        })
        const result = await callWithBindings(async (root: any) => {
          return root.example.callWithNumber((n: number) => n + 1)
        })
        expect(result).to.equal(124)
      })

      it('should proxy promises in the reverse direction', async () => {
        await makeBindingWindow(() => {
          contextBridge.exposeInMainWorld('example', {
            getPromiseValue: (p: Promise<any>) => p
          })
        })
        const result = await callWithBindings((root: any) => {
          return root.example.getPromiseValue(Promise.resolve('my-proxied-value'))
        })
        expect(result).to.equal('my-proxied-value')
      })

      it('should proxy objects with number keys', async () => {
        await makeBindingWindow(() => {
          contextBridge.exposeInMainWorld('example', {
            1: 123,
            2: 456,
            '3': 789
          })
        })
        const result = await callWithBindings(async (root: any) => {
          return [root.example[1], root.example[2], root.example[3], Array.isArray(root.example)]
        })
        expect(result).to.deep.equal([123, 456, 789, false])
      })

      it('it should proxy null and undefined correctly', async () => {
        await makeBindingWindow(() => {
          contextBridge.exposeInMainWorld('example', {
            values: [null, undefined]
          })
        })
        const result = await callWithBindings((root: any) => {
          // Convert to strings as although the context bridge keeps the right value
          // IPC does not
          return root.example.values.map((val: any) => `${val}`)
        })
        expect(result).to.deep.equal(['null', 'undefined'])
      })

      it('should proxy typed arrays and regexps through the serializer', async () => {
        await makeBindingWindow(() => {
          contextBridge.exposeInMainWorld('example', {
            arr: new Uint8Array(100),
            regexp: /a/g
          })
        })
        const result = await callWithBindings((root: any) => {
          return [
            Object.getPrototypeOf(root.example.arr) === Uint8Array.prototype,
            Object.getPrototypeOf(root.example.regexp) === RegExp.prototype
          ]
        })
        expect(result).to.deep.equal([true, true])
      })

      it('it should handle recursive objects', async () => {
        await makeBindingWindow(() => {
          const o: any = { value: 135 }
          o.o = o
          contextBridge.exposeInMainWorld('example', {
            o
          })
        })
        const result = await callWithBindings((root: any) => {
          return [root.example.o.value, root.example.o.o.value, root.example.o.o.o.value]
        })
        expect(result).to.deep.equal([135, 135, 135])
      })

      // Can only run tests which use the GCRunner in non-sandboxed environments
      if (!useSandbox) {
        it('should release the global hold on methods sent across contexts', async () => {
          await makeBindingWindow(() => {
            require('electron').ipcRenderer.on('get-gc-info', e => e.sender.send('gc-info', (contextBridge as any).debugGC()))
            contextBridge.exposeInMainWorld('example', {
              getFunction: () => () => 123
            })
          })
          expect((await getGCInfo()).functionCount).to.equal(2)
          await callWithBindings(async (root: any) => {
            root.x = [root.example.getFunction()]
          })
          expect((await getGCInfo()).functionCount).to.equal(3)
          await callWithBindings(async (root: any) => {
            root.x = []
            root.GCRunner.run()
          })
          expect((await getGCInfo()).functionCount).to.equal(2)
        })
      }

      it('it should not let you overwrite existing exposed things', async () => {
        await makeBindingWindow(() => {
          let threw = false
          contextBridge.exposeInMainWorld('example', {
            attempt: 1,
            getThrew: () => threw
          })
          try {
            contextBridge.exposeInMainWorld('example', {
              attempt: 2,
              getThrew: () => threw
            })
          } catch {
            threw = true
          }
        })
        const result = await callWithBindings((root: any) => {
          return [root.example.attempt, root.example.getThrew()]
        })
        expect(result).to.deep.equal([1, true])
      })

      it('should work with complex nested methods and promises', async () => {
        await makeBindingWindow(() => {
          contextBridge.exposeInMainWorld('example', {
            first: (second: Function) => second((fourth: Function) => {
              return fourth()
            })
          })
        })
        const result = await callWithBindings((root: any) => {
          return root.example.first((third: Function) => {
            return third(() => Promise.resolve('final value'))
          })
        })
        expect(result).to.equal('final value')
      })

      it('should throw an error when recursion depth is exceeded', async () => {
        await makeBindingWindow(() => {
          contextBridge.exposeInMainWorld('example', {
            doThing: (a: any) => console.log(a)
          })
        })
        let threw = await callWithBindings((root: any) => {
          try {
            let a: any = []
            for (let i = 0; i < 999; i++) {
              a = [ a ]
            }
            root.example.doThing(a)
            return false
          } catch {
            return true
          }
        })
        expect(threw).to.equal(false)
        threw = await callWithBindings((root: any) => {
          try {
            let a: any = []
            for (let i = 0; i < 1000; i++) {
              a = [ a ]
            }
            root.example.doThing(a)
            return false
          } catch {
            return true
          }
        })
        expect(threw).to.equal(true)
      })

      it('should not leak prototypes', async () => {
        await makeBindingWindow(() => {
          contextBridge.exposeInMainWorld('example', {
            number: 123,
            string: 'string',
            boolean: true,
            arr: [123, 'string', true, ['foo']],
            getNumber: () => 123,
            getString: () => 'string',
            getBoolean: () => true,
            getArr: () => [123, 'string', true, ['foo']],
            getPromise: async () => ({ number: 123, string: 'string', boolean: true, fn: () => 'string', arr: [123, 'string', true, ['foo']] }),
            getFunctionFromFunction: async () => () => null,
            object: {
              number: 123,
              string: 'string',
              boolean: true,
              arr: [123, 'string', true, ['foo']],
              getPromise: async () => ({ number: 123, string: 'string', boolean: true, fn: () => 'string', arr: [123, 'string', true, ['foo']] })
            },
            receiveArguments: (fn: any) => fn({ key: 'value' })
          })
        })
        const result = await callWithBindings(async (root: any) => {
          const { example } = root
          let arg: any
          example.receiveArguments((o: any) => { arg = o })
          const protoChecks = [
            [example, Object],
            [example.number, Number],
            [example.string, String],
            [example.boolean, Boolean],
            [example.arr, Array],
            [example.arr[0], Number],
            [example.arr[1], String],
            [example.arr[2], Boolean],
            [example.arr[3], Array],
            [example.arr[3][0], String],
            [example.getNumber, Function],
            [example.getNumber(), Number],
            [example.getString(), String],
            [example.getBoolean(), Boolean],
            [example.getArr(), Array],
            [example.getArr()[0], Number],
            [example.getArr()[1], String],
            [example.getArr()[2], Boolean],
            [example.getArr()[3], Array],
            [example.getArr()[3][0], String],
            [example.getFunctionFromFunction, Function],
            [example.getFunctionFromFunction(), Promise],
            [await example.getFunctionFromFunction(), Function],
            [example.getPromise(), Promise],
            [await example.getPromise(), Object],
            [(await example.getPromise()).number, Number],
            [(await example.getPromise()).string, String],
            [(await example.getPromise()).boolean, Boolean],
            [(await example.getPromise()).fn, Function],
            [(await example.getPromise()).fn(), String],
            [(await example.getPromise()).arr, Array],
            [(await example.getPromise()).arr[0], Number],
            [(await example.getPromise()).arr[1], String],
            [(await example.getPromise()).arr[2], Boolean],
            [(await example.getPromise()).arr[3], Array],
            [(await example.getPromise()).arr[3][0], String],
            [example.object, Object],
            [example.object.number, Number],
            [example.object.string, String],
            [example.object.boolean, Boolean],
            [example.object.arr, Array],
            [example.object.arr[0], Number],
            [example.object.arr[1], String],
            [example.object.arr[2], Boolean],
            [example.object.arr[3], Array],
            [example.object.arr[3][0], String],
            [await example.object.getPromise(), Object],
            [(await example.object.getPromise()).number, Number],
            [(await example.object.getPromise()).string, String],
            [(await example.object.getPromise()).boolean, Boolean],
            [(await example.object.getPromise()).fn, Function],
            [(await example.object.getPromise()).fn(), String],
            [(await example.object.getPromise()).arr, Array],
            [(await example.object.getPromise()).arr[0], Number],
            [(await example.object.getPromise()).arr[1], String],
            [(await example.object.getPromise()).arr[2], Boolean],
            [(await example.object.getPromise()).arr[3], Array],
            [(await example.object.getPromise()).arr[3][0], String],
            [arg, Object],
            [arg.key, String]
          ]
          return {
            protoMatches: protoChecks.map(([a, Constructor]) => Object.getPrototypeOf(a) === Constructor.prototype)
          }
        })
        // Every protomatch should be true
        expect(result.protoMatches).to.deep.equal(result.protoMatches.map(() => true))
      })
    })
  }

  generateTests(true)
  generateTests(false)
})