browser-do

Run JavaScript in a browser, forward browser console log to stdout, great for running unit tests in browser.

npm i -D browser-do

Requires minimum Node.js v10.13+.

browser-do is an alternative implementation of browser-run and tape-run, with better Windows support, supports running mocha, jasmine, tape unit tests out of the box.

browser-do offers:

1. Browser detection borrowed from various karma browser launchers. Simpler and more reliable on Windows than browser-launcher.
2. TAP output support.
3. Kept browser-run options -p, --port, -b, --browser browser-name, -s, --static, and -m, --mock.
4. Removed --input html as browser-do auto detects input format.
5. Removed -n, --node and --basedir as browser-do doesn't want to support Node.js code. (In original browser-run, Node.js code only works with electron anyway)
6. Added options -t, --tap to handle generic TAP output.
7. Added --jasmine and --mocha to conveniently support jasmine/mocha (setup global vars, switch to TAP reporter).
8. Added -k, --keep-open (inherited from tap-run) to keep browser running after TAP finished.

browser-do is simple and flexible. Just pipe your code to browser-do with a browser of your choice (default to a headless electron).

browserify test/all-my-tape-tests.js | browser-do --tap
browserify test/all-my-jasmine-tests.js | browser-do --jasmine
browserify test/all-my-mocha-tests.js | browser-do --mocha --browser chrome-headless

Note browserify doesn't support glob, that's why we cannot use browserify 'test/**/*.spec.js' here.

You don't need to use browserify with browser-do. You can prepare a JavaScript bundle with any bundler, then just pipe it to browser-do.

cat dist/my-test-bundle.js | browser-do --tap # or jasmine/mocha
# or avoid "cat" on windows
browser-do --tap < dist/my-test-bundle.js
# Or in PowerShell
Get-Content dist/my-test-bundle.js | browser-do --tap # or jasmine/mocha

One more tip, because browser-do normalises tape/jasmine/mocha into TAP output, you can further pipe it to any TAP pretty reporters

browserify test/all-my-jasmine-tests.js | browser-do --jasmine | tap-dot

Supported Browsers

electron is the always available default.

	macOS	Linux	Windows
electron (default)	Yes	Yes	Yes
chrome	Yes	Yes	Yes
chrome-headless	Yes	Yes	Yes
chromium	Yes	Yes	Yes
chromium-headless	Yes	Yes	Yes
firefox	Yes	Yes	Yes
firefox-headless	Yes	Yes	Yes
edge	Yes		Yes
edge-headless	Yes		Yes
safari	Yes

browser-do v4+ dropped support of Microsoft IE. To work with IE, please use browser-do v3. browser-do v2+ only supports Chromium based Microsoft Edge. To work with old Microsoft Edge, please use browser-do v1.

Usage

Usage: browser-do [options]

Options:
  -V, --version         output the version number
  -b, --browser <name>  Browser to use, see available browsers below (default: "electron")
  -p, --port <port>     Starts listening on that port and waits for you to open a browser
  -s, --static <path>   Serve static assets from this directory
  -m, --mock <path>     Path to code to handle requests for mocking a dynamic back-end
  -t, --tap             Treat output as TAP test result, automatically exit when TAP finishes
  --jasmine             Support jasmine test, uses jasmine TAP reporter, implicitly turns on option "tap", automatically exit when TAP finishes
  --mocha               Support mocha test, assumes BDD setup, uses TAP reporter, implicitly turns on option "tap", automatically exit when TAP finishes
  -k, --keep-open       Only for -t, --tap, --jasmine and --mocha, leave the browser open for debugging after running tests
  -h, --help            output usage information

Available browsers if installed (for -b, --browser <name>):
  electron (embedded, default choice), chrome, chrome-headless, chromium, chromium-headless, firefox, firefox-headless, edge, edge-headless, safari

There is some tolerance on browser name, for example:
  -b ChromeHeadless
  -b chromeHeadless
  -b chrome_headless
  -b "chrome headless"
all work just like -b chrome-headless

Custom html file

Your can provide a custom html file for browser-do to use. Keep in mind it always needs to have <script src="/reporter.js"></script> above other script tags so browser-do is able to properly forward your console.logs etc to the terminal.

Different from browser-run, you don't need --input html, browser-do detects the input automatically.

You would need to combine custom html file with --static some-dir or --mock mock-code.js in order to have some way to load your JavaScript code.

Dynamic back-end mock

By using --mock mock.js (or { mock: 'mock.js'} in code) you can provide a custom server-side implementation and handle all requests that are sent to paths beginning with /mock

mock.js needs to export a function that accepts req and res arguments for handling requests.

Example:

module.exports = function(req, res){
  if (req.url === '/mock/echo') {
    req.pipe(res);
  }
};

Run browser-do in code

API: run(opts), all the opts have same meaning as the command line options.

port, browser, static, mock, tap, jasmine, mocha, and keepOpen.

var run = require('browser-do');

var browser = run();
browser.pipe(process.stdout);
browser.end('console.log(location); window.close()');

Note window.close() will quit the default electron browser, but it would not work with some other browsers. Because many browsers reject window.close() for a window not opened by JavaScript. (In browser perspective, it opened a URL, although browser-do programmatically did that.)

Close browser window by code

When using browser-do in code with a browser not electron, you have to close the window manually (only if you didn't use tap, jasmine or mocha option).

var run = require('browser-do');

var browser = run({browser: 'chrome'});
browser.pipe(process.stdout);
browser.end('console.log(location);');

setTimeout(function() { browser.stop(); }, 5000);

Get TAP result by code

Follow example takes unit test JS code from stdin, capture final result (either pass or fail).

var run = require('browser-do');

var browser = run({tap: true}); // or jasmine: true, or mocha: true
process.stdin.pipe(browser).pipe(process.stdout);

browser.on('exit', code => {
  // the code is 0 for passed tests, 1 for failed tests
});

Note browser-do only generates a simple pass/fail result from the whole TAP output. browser-do retains original TAP output, so if you need detailed TAP output parsing, further pipe the stream to tap-parser.

Unit tests support

browser-do conveniently supports running mocha, jasmine, tape unit tests out of the box.

Tape

Tape is easy to support, as it doesn't pollute global variables. All browser-do needs to do is to parse TAP output and automatically exit when tests finish.

browserify some-tap-test.js | browser-do -t # or --tap

Jasmine

browser-do helps jasmine test by setup global vars before running your code.

browserify some-jasmine-test.js | browser-do --jasmine

You don't need to load jasmine before running your code, browser-do does that automatically, as long as you did npm i -D jasmine-core.

FYI, here is the special index.html browser-do provided for jasmine. Showing here only to help you to understand how browser-do does the magic.

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <script src="/reporter.js"></script>
  <link rel="stylesheet" href="/jasmine-core/jasmine.css">
</head>
<body>
  <script src="/jasmine-core/jasmine.js"></script>
  <script src="/jasmine-core/jasmine-html.js"></script>
  <script src="/jasmine-core/boot0.js"></script>
  <script src="/jasmine-core/boot1.js"></script>
  <script src="/jasmine-tap-reporter.js"></script>
  <script src="/bundle.js"></script> <!-- Your code is loaded here! -->
</body>
</html>

Mocha

browser-do helps mocha test by setup global vars before running your code.

browserify some-mocha-test.js | browser-do --mocha

You don't need to load mocha before running your code, browser-do does that automatically, as long as you did npm i -D mocha.

FYI, here is the special index.html browser-do provided for mocha. Showing here only to help you to understand how browser-do does the magic.

Note we use default BDD style in mocha.

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <script src="/reporter.js"></script>
  <link rel="stylesheet" href="/mocha/mocha.css">
</head>
<body>
  <div id="mocha"></div>
  <script src="/mocha/mocha.js"></script>
  <script class="mocha-init">
    mocha.setup({ui: "bdd", reporter: "tap"});
  </script>
  <script src="/bundle.js"></script> <!-- Your code is loaded here! -->
  <script class="mocha-exec">
    mocha.run();
  </script>
</body>
</html>

The default mocha setup uses "tap" reporter so browser-do can understand tests result.

Only for mocha, when -k, --keep-open option is on, it switches setup to use "html" reporter. Because mocha doesn't support multiple reporters, and we want to show user a nice result in browser window. As a result, browser-do cannot detect the final test result in keepOpen mode.

If you want to use different setup of mocha, just pipe a custom html file to browser-do

cat my-mocha-index.html | browser-do --mocha --static .
# or avoid "cat" on windows
browser-do --mocha --static . < my-mocha-index.html

In your special html file:

1. you need <script src="/reporter.js"></script> above any script tags.
2. you need retain most of the above html file, just modify the mocha setup part.
3. you need something like <script src="/dist/my-prepared-bundle.js"></script> to replace <script src="/bundle.js"></script>, you need to make sure you generated that bundle file before using browser-do.
4. The --static . option is to let browser-do to access all the local files including the dist/my-prepared-bundle.js.

CI setup

GitHub Actions

When running unit tests with browser-do, you need xvfb on Linux.

- run: xvfb-run -a npm test
  if: runner.os == 'Linux'
- run: npm test
  if: runner.os != 'Linux'

You may also need to enlarge xvfb default screen size (640x480x8) for your tests.

xvfb-run -a -s '-screen 0 1024x768x24' npm test

Travis

To use browser-do on travis, add this to your .travis.yml:

addons:
  apt:
    packages:
      - xvfb
before_install:
  - export DISPLAY=':99.0'
  - Xvfb :99 -screen 0 1024x768x24 > /dev/null 2>&1 &

If you run travis with multiple OS including windows:

os:
  - linux
  - windows
  - osx
addons:
  apt:
    packages:
      - xvfb
before_install:
  - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then export DISPLAY=':99.0' ; fi
  - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then Xvfb :99 -screen 0 1024x768x24 > /dev/null 2>&1 & fi

Code coverage report

browser-do supports code coverage in a humble way. To understand how browser-do supports it, first we need to understand how nyc/Istanbul works internally.

To generate code coverage report, when in Node.js environment, nyc/Istanbul needs to

1. instrument source code. It injects special code into your source code in order to gather code coverage information.
2. when running unit tests, those instrumented source code writes code coverage information into an intermediate JavaScript object global.__coverage__. This becomes window.__coverage__ in browser.
3. nyc automatically writes global.__coverage__ object to a local json file in .nyc_output/ folder.
4. nyc then uses various reporters to turn the json file into human readable report (text summary, or html file).

When running browser-do, your unit tests is running in browser. All browser-do does is:

1. if your source code is instrumented, it will generate window.__coverage__ object. browser-do does nothing here.
2. when tape/jasmine/mocha tests finished, browser-do check whether there is window.__coverage__. If so, it will write the object to .nyc_output/out.json (the default nyc output file).

You then can follow it up with another command to turn that json file into readable report!

npx nyc report --reporter=lcov --reporter=text

Here browser-do does the bare minimum job: only writes window.__coverage__ into .nyc_output/out.json when window.__coverage__ exits.

The task of instrumenting is not handled by browser-do, nor should (as browser-do is the consumer of a piece of JavaScript, not the creator).

babel-plugin-istanbul

For projects using babel, you can easily turn on babel-plugin-istanbul in test environment. That plugin will instrument your code.

I have not found out what's the native way to instrument TypeScript file. But if you use babel to compile ts files, you can continue to use babel-plugin-istanbul.

For example on babel-plugin-istanbul + browser-do + nyc, try to create a SPA app with dumberjs skeleton:

npx makes dumberjs

Choose Aurelia or Vue (but not .vue single file component), babel, jasmine/mocha/tape, (not jest. jest runs in Node.js, not browser, is irrelevant here). Then follow the README file on code coverage. Note the React non-jest setup has some trouble in code coverage right now.

License

browser-do is licensed under the MIT license.

Acknowledgement

browser-do borrowed code from many projects, details in ACKNOWLEDGEMENT.