react-native/Libraries/Blob/__tests__/FileReader-test.js

/**
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * @format
 * @oncall react_native
 */

'use strict';

jest.unmock('event-target-shim').setMock('../../BatchedBridge/NativeModules', {
  BlobModule: require('../__mocks__/BlobModule'),
  FileReaderModule: require('../__mocks__/FileReaderModule'),
});

const Blob = require('../Blob');
const FileReader = require('../FileReader');

describe('FileReader', function () {
  it('should read blob as text', async () => {
    const e = await new Promise((resolve, reject) => {
      const reader = new FileReader();
      reader.onload = resolve;
      reader.onerror = reject;
      reader.readAsText(new Blob());
    });
    expect(e.target.result).toBe('');
  });

  it('should read blob as data URL', async () => {
    const e = await new Promise((resolve, reject) => {
      const reader = new FileReader();
      reader.onload = resolve;
      reader.onerror = reject;
      reader.readAsDataURL(new Blob());
    });
    expect(e.target.result).toBe('data:text/plain;base64,NDI=');
  });

  it('should read blob as ArrayBuffer', async () => {
    const e = await new Promise((resolve, reject) => {
      const reader = new FileReader();
      reader.onload = resolve;
      reader.onerror = reject;
      reader.readAsArrayBuffer(new Blob());
    });
    const ab = e.target.result;
    expect(ab.byteLength).toBe(2);
    expect(new TextDecoder().decode(ab)).toBe('42');
  });
});