Helps read and compare files downloaded during a protractor e2e test

protractor-download-helper.ts

// <project_root>/e2e/protractorDownloads/protractor-download-helper.ts

import { browser } from 'protractor';

const fs = require('fs');
const path = require('path');

export class ProtractorDownloadHelper {
  private readonly maxReadWaitTime = 10000; // 10 seconds

  constructor() {
  }

  removeFile(fileName: string): void {
    this.removeFileAtPath(this.getFilePath(fileName));
  }

  async getFileContents(fileName: string): Promise<string> {
    const filePath: string = this.getFilePath(fileName);
    try {
      await browser.driver.wait(() => {
        // Wait until the file exists, download may take some time
        return fs.existsSync(filePath);
      }, this.maxReadWaitTime);
    } catch (err) {
      throw new Error(`File ${filePath} does not exist`);
    }

    return fs.readFileSync(filePath, { encoding: 'utf8' });
  }

  private removeFileAtPath(filePath: string): void {
    if (fs.existsSync(filePath)) {
      fs.unlinkSync(filePath);
    }
  }

  private getFilePath(fileName: string): string {
    return path.join(__dirname, fileName);
  }
}

/*

Sample use:

// <project_root>/e2e/your-test.e2e-spec.ts

import { ProtractorDownloadHelper } from './protractorDownloads/protractor-download-helper';

describe('Your test', () => {

  it('should download proper file', async () => {
    const downloadedFileName = 'download.json';
    const expectedDownloadFileName = 'expected_download.json';

    // Remove the existing download file, if any (so browser doesn't rename the file)
    const downloadHelper: ProtractorDownloadHelper = new ProtractorDownloadHelper();
    downloadHelper.removeFile(downloadedFileName);

    // Click the download button
    $('.download-link').click();

    // Verify file contents
    try {
      const actualFileContents: string = await this.getFileContents(downloadedFileName);
      const expectedFileContents: string = await this.getFileContents(expectedDownloadFileName);
      expect(actualFileContents).toBe(expectedFileContents, 'Downloaded file differs from expected download file');
    } catch (err) {
      fail(`ERROR: Exception thrown: ${err.message}`);
    }

    // Remove file
    downloadHelper.removeFile(downloadedFileName);
  });

});

*/

/*

Sample config:

// <project_root>/protractor.conf.js

const path = require('path');
const downloadsPath = path.resolve(__dirname, './e2e/protractorDownloads');

exports.config = {
  capabilities: {
    browserName: 'chrome',
    chromeOptions: {
      args: [
        '--no-sandbox',
        '--test-type=browser'
      ],
      prefs: {
        download: {
          prompt_for_download: false,
          default_directory: downloadsPath
        }
      }
    }
  },
};

*/

Can you please paste a screenshot here? All of the this references in the gist seem fine to me.