Runner Class

An object that configures and launches test tasks.

Created by the testCafe.createRunner function.


const createTestCafe = require('testcafe');
let testcafe         = null;

createTestCafe('localhost', 1337, 1338)
    .then(tc => {
        testcafe     = tc;
        const runner = testcafe.createRunner();

        return runner
            .src(['tests/fixture1.js', 'tests/func/fixture3.js'])
            .browsers(['chrome', 'safari'])
    .then(failedCount => {
        console.log('Tests failed: ' + failedCount);



Configures the test runner to run tests from the specified files.

src(source) → this
Parameter Type Description
source String | Array The relative or absolute path to a test fixture file, or several such paths.

Concatenates the settings when called several times.


runner.src(['/home/user/tests/fixture1.js', 'fixture5.js']);


Allows you to manually select which tests should be run.

filter(callback) → this
Parameter Type Description
callback function(testName, fixtureName, fixturePath) The callback that determines if a particular test should be run.

The callback function is called for each test in files that are specified using the src method.

Return true from the callback to include the current test, or false to exclude it.

The callback function takes the following arguments.

Parameter Type Description
testName String The name of the test.
fixtureName String The name of the test fixture.
fixturePath String The path to the test fixture file.


runner.filter((testName, fixtureName, fixturePath) => {
    return fixturePath.startsWith('D') &&
        testName.match(someRe) &&


Configures the test runner to run tests in the specified browsers.

browsers(browser) → this

The browser parameter can be any of the following objects, or an Array of them.

Parameter Type Description Browser Type
String The browser alias that differs for different browser types. For details, see Browser Support. Local browsers, cloud browsers and browsers accessed through browser provider plugins.
{path: String, cmd: String} The path to the browser executable (path) and command line parameters (cmd). The cmd property is optional. Local and portable browsers
BrowserConnection The remote browser connection. Remote browsers

You are free to mix different types of objects in one function call. The browsers function concatenates the settings when called several times.

Using Browser Aliases

  • running local browsers
runner.browsers(['safari', 'chrome']);
  • running browsers accessed through browser provider plugins
runner.browsers('saucelabs:Chrome@52.0:Windows 8.1');

Specifying the Path to the Browser Executable

runner.browsers('C:\\Program Files\\Internet Explorer\\iexplore.exe');

Specifying the Path with Command Line Parameters

    path: 'C:\\Program Files\\Google\\Chrome\\Application\\chrome.exe',
    cmd: '--new-window'

Passing a Remote Browser Connection

const createTestCafe = require('testcafe');
let runner           = null;
let testcafe         = null;

createTestCafe('localhost', 1337, 1338)
    .then(tc => {
        testcafe = tc;
        runner   = testcafe.createRunner();

        return testcafe.createBrowserConnection();
    .then(remoteConnection => {

        // Outputs remoteConnection.url so that it can be visited from the remote browser.

        remoteConnection.once('ready', () => {
                .then(failedCount => {


Enables TestCafe to take screenshots of the tested webpages.

screenshots(path [, takeOnFails]) → this
Parameter Type Description Default
path String The path to which the screenshots will be saved.
takeOnFails (optional) Boolean Specifies if screenshots should be taken automatically whenever a test fails. false

The screenshots function must be called to enable TestCafe to take screenshots when the t.takeScreenshot action is called from test code.

Set the takeOnFails parameter to true to additionally take a screenshot whenever a test fails.

If the screenshots function is not called, TestCafe does not take screenshots.


runner.screenshots('reports/screenshots/', true);


Configures the TestCafe reporting feature.

reporter(name [, outStream]) → this
Parameter Type Description Default
name String The name of the reporter to use.
outStream (optional) Writable Stream implementer The stream to which the report will be written. stdout

Specifying the Reporter


Saving the Report to a File

const stream = fs.createWriteStream('report.xml');

    .reporter('xunit', stream)
    .then(failedCount => {

Implementing a Custom Stream

class MyStream extends stream.Writable {
    _write(chunk, encoding, next) {

const stream = new MyStream();
runner.reporter('json', stream);

You can also build your own reporter. Use a dedicated Yeoman generator to scaffold out a reporter plugin.


Specifies that tests should run concurrently.

concurrency(n) → this

TestCafe will open n instances of the same browser thus creating a pool of browser instances. Tests will run concurrently against this pool, i.e. each test will run in the first free instance.

The concurrency function takes the following parameters.

Parameter Type Description
n Number The number of browser instances that will be invoked.

To learn more about concurrent test execution, see Concurrent Test Execution.

The following example shows how to run tests in three Chrome instances.



Specifies a shell command that will be executed before running tests. Use it to launch or deploy the application that will be tested.

async startApp(command, initDelay) → this

After the testing is finished, the appication will be automatically terminated.

The startApp function takes the following parameters.

Parameter Type Description Default
command String The shell command to be executed.
initDelay (optional) Number The amount of time, in milliseconds, allowed for the command to initialize the tested application.

TestCafe adds node_modules/.bin to PATH so that you can use binaries provided by locally installed dependencies without prefixes.


runner.startApp('node server.js', 4000);


Specifies the proxy server used in your local network to access the Internet.

async useProxy(host) → this
Parameter Type Description
host String The proxy server host.



You can also specify authentication credentials with the proxy host.



Runs tests according to the current configuration. Returns the number of failed tests.

async run(options) → Promise<Number>

Make sure to keep the browser tab that is running tests active. Do not minimize the browser window. Inactive tabs and minimized browser windows switch to a lower resource consumption mode where tests are not guaranteed to execute correctly.

You can pass the following options to the function.

Parameter Type Description Default
skipJsErrors Boolean Defines whether to continue running a test after a JavaScript error occurs on a page (true), or consider such a test failed (false). false
quarantineMode Boolean Defines whether to enable the quarantine mode. false
selectorTimeout Number Specifies the amount of time, in milliseconds, within which selectors make attempts to obtain a node to be returned. See Selector Timeout. 10000
assertionTimeout Number Specifies the amount of time, in milliseconds, within which TestCafe makes attempts to successfully execute an assertion if a selector property or a client function was passed as an actual value. See Smart Assertion Query Mechanism. 3000
speed Number Specifies the speed of test execution. Should be a number between 1 (the fastest) and 0.01 (the slowest). If speed is also specified for an individual action, the action speed setting overrides test speed. 1
debugMode Boolean Specifies if tests run in the debug mode. If this option is enabled, test execution is paused before the first action or assertion allowing you to invoke the developer tools and debug. false

After all tests are finished, call the testcafe.close function to stop the TestCafe server.


const createTestCafe = require('testcafe');
let testcafe         = null;

createTestCafe('localhost', 1337, 1338)
    .then(tc => {
        testcafe     = tc;
        const runner = testcafe.createRunner();

            skipJsErrors: true,
            quarantineMode: true,
            selectorTimeout: 50000,
            assertionTimeout: 7000,
            speed: 0.1
    .then(failed => {
        console.log('Tests failed: ' + failed);
    .catch(error => { /* ... */ });

Cancelling Test Tasks

You can stop an individual test task at any moment by cancelling the corresponding promise.

const taskPromise = runner
    .browsers([remoteConnection, 'chrome'])


You can also cancel all pending tasks at once by using the runner.stop function.

Quarantine Mode

The quarantine mode is designed to isolate non-deterministic tests (i.e., tests that sometimes pass and sometimes fail without a clear reason) from the rest of the test base (healthy tests).

When the quarantine mode is enabled, tests are not marked as failed after the first unsuccessful run but rather sent to quarantine. After that, these tests are run several more times. The outcome of the most runs (passed or failed) is recorded as the test result. A test is separately marked unstable if the outcome varies between runs. The run that led to quarantining the test counts.

To learn more about the issue of non-deterministic tests, see Martin Fowler's Eradicating Non-Determinism in Tests article.


Stops all pending test tasks.

async stop()

You can also stop an individual pending task by cancelling the corresponding promise.