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);
});