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Small JS framework to provide headless browser-based tests.


This framework provides the possibility to quickly check browser UI through small script files (with the .goml extension). By default, once the script is done running, it takes a screenshot of the page and compares it to the expected one. If they're different, the test will fail.

Quick links

This is a big README, so to make you go through it faster:

How to install

This framework is hosted on npmjs here. Therefore, you can install it locally using this command:

npm install browser-ui-test

Trouble installing puppeteer?

In case you can't install puppeteer "normally", you can give a try to --unsafe-perm=true:

$ npm install puppeteer --unsafe-perm=true


You can either use this framework by using it as dependency or running it directly. In both cases you'll need to write some .goml scripts. It looks like this:

go-to: "" // go to this url
set-text: ("#button", "hello") // set text of element #button
assert-text: ("#button", "hello") // check if #button element's text has been set to "hello"

The list of the commands is available here.

Using this framework as a binary

If you installed it, you should have a script called "browser-ui-test". You can run it as follows:

$ browser-ui-test --test-files some-file.goml

To see the list of available options, use -h or --help:

$ browser-ui-test --help

Using Docker

This repository provides a Dockerfile in case you want to make your life easier when running tests. For example, the equivalent of running npm run test is:

# in case I am in the browser-UI-test folder
$ docker build . -t browser-ui
$ docker run \
    -v "$PWD:/data" \
    -u $(id -u ${USER}):$(id -g ${USER}) \
    browser-ui \
    # browser-ui-test options from this point
    --test-folder /data/tests/scripts/ \
    --failure-folder /data/failures \
    --variable DOC_PATH /data/tests/html_files

Explanations for these commands! The first one builds an image using the current folder and names it "browser-ui".

The second one runs using what we built in the first command. Two important things here are -v "$PWD:/data" and -u $(id -u ${USER}):$(id -g ${USER}).

-v "$PWD:/data" is used to tell docker to bind the current folder ($PWD) in the /data folder in the context of docker. If you want to bind another folder, just change the $PWD value. Please remember that you need to use absolute paths!

-u $(id -u ${USER}):$(id -g ${USER}) is used to run the docker container as the current user so that the generated files aren't owned by root (which can quickly become annoying).

Then we tell it to run the "browser-ui" image.

For the rest, --test-folder, --failure-folder and --variable are browser-UI-test options. You'll note that I prepended them with "/data" because this is where we mounted the volume in the docker instance. To know what the options are for, please refer to the Options part of this README.

Docker hub

Important note: each merge on master pushes a new image on docker hub. You can find them here.

There are three kinds of docker images:

  1. By (npm) version
  2. Latest master branch update
  3. By date

Using this framework as a dependency

You can do so by importing both runTests and Options from index.js. Options is a class where you can set the parameters you need/want. If you feel better providing "command-line args"-like parameters, you can use it as follows:

const {Options, runTests} = require('browser-ui-test');

const options = new Options();
try {
    // This is more convenient that setting fields one by one.
    options.parseArguments(['--enable-screenshot-comparison', '--test-folder', 'some-other-place']);
} catch (error) {
    console.error(`invalid argument: ${error}`);

Then you just pass this options variable to the runTests function and it's done:

runTests({"options": options}).then(x => {
    const [output, nb_failures] = x;
}).catch(err => {

To be noted that there is also a function runTest which only runs the specified test file:

const {runTest} = require('browser-ui-test');

runTest('someFile.goml').then(x => {
    const [output, nb_failures] = x;
}).catch(err => {

And if you already have the content of a test, you can use runTestCode:

const {runTestCode} = require('browser-ui-test');

runTestCode('someFile.goml', 'go-to: "file://" + |CURRENT_DIR| + "/path"').then(x => {
    const [output, nb_failures] = x;
}).catch(err => {

Optional arguments

All these functions can take an extra argument (you can see it in runTests with {"options": options}). It expects a dictionary which can contains the following fields:

  • options: If not set, it'll be created with new Options().
  • browser: null by default, expected to be created from loadBrowser otherwise.
  • showLogs: If not set, it'll be set to false.

The browser optional argument allows you tu re-use the same Browser instance instead of a re-creating a new one for each test. You can get this object by calling the loadBrowser function. It expects a Options argument.

Exported elements

Like said above, you can use this framework through code directly. Here is the list of available elements:

  • runTest: Function to run a specific test. Parameters:
  • runTestCode: Function to run a specific inline test. Parameters:
    • testName: String [MANDATORY]
    • content: String [MANDATORY] (content representing the .goml content script)
    • extras: Dictionary [OPTIONAL] (see Optional arguments)
  • runTests: Function to run tests based on the received options. Parameters:
  • loadBrowser: Function to create a new connection to the underlying web browser. Parameters:
    • options: Options [MANDATORY]
  • Options: Object used to store run options. More information follows in the Options section.


If you want to see all the available options, just run with the -h or --help options. If you want to build the Options object yourself, you might be interested by what follows.

The list of fields of the Options class is the following:

  • allowFileAccessFromFiles: if set to true, it will disable CORS errors for local files
  • debug: display more information
  • emulate: name of the device you want to emulate (list of available devices is here or you can use --show-devices option)
  • executablePath: browser's executable path to be used
  • extensions: extensions to be loaded by the browser
  • failOnJsError: if set to true, if a web page has a JS error, the test will fail
  • failOnRequestError: if set to true (its default value), if a request fails, the test will fail
  • failureFolder: path of the folder where failed tests image will be placed (testFolder value by default)
  • generateImages: if provided, it'll generate test images and won't run comparison tests
  • imageFolder: path of the folder where screenshots are and where they are generated (testFolder value by default)
  • incognito: whether or not the browser is running in incognito mode
  • nbThreads: number of parallel jobs, defaults to number of CPUs
  • noHeadless: disable headless mode
  • screenshotComparison: enable screenshots generation and comparison at the end of the scripts
  • screenshotOnFailure: takes a screenshot if a test fails and stops the test execution
  • onPageCreatedCallback: callback which is called when a new puppeteer page is created. It provides the puppeteer page and the test name as arguments
  • pauseOnError: will pause indefinitely if an error occurs.
  • permissions: list of permissions to enable (you can see the full list by running with --show-permissions)
  • runId: id to be used for failed images extension ('test' by default)
  • showText: disable text invisibility (be careful when using it!)
  • testFiles: list of .goml files' path to be run
  • testFolder: path of the folder where .goml script files are
  • timeout: number of milliseconds that'll be used as default timeout for all commands interacting with the browser. Defaults to 30 seconds, cannot be less than 0, if 0, it means it'll wait undefinitely so use it carefully!
  • variables: variables to be used in the .goml scripts (more information about variables below)

Running it directly

You need to pass options through the command line but it's basically the same as doing it with code. Let's run it with the same options as presented above:

$ node src/index.js --test-folder some-other-place

Font issues

Unfortunately, font rendering differs depending on the computer and on the OS. To bypass this problem but still allow to have a global UI check, the text is invisible by default. If you are sure that you need to check with the text visible, you can use the option --show-text.

Run tests

If you want to run this repository's scripts tests:

$ node src/index.js --test-folder tests/scripts/ --failure-folder failures --variable DOC_PATH tests/html_files

Or more simply:

$ npm test

If you want to test "internals", run:

$ npm run all-test

If you want to run test suites separately:

$ npm run api-test
$ npm run parser-test
$ npm run exported-test
$ npm run generated-test
$ npm run ui-test

To be noted, ui-test and api-test can be run with --bless to fix the differences:

$ npm run api-test --bless
$ npm run ui-test --bless


If you appreciate my work and want to support me, you can do it here: