Compatibility

The instrumentation works at runtime, so any transpilers such as TypeScript, Webpack, or Babel are supported out-of-the-box.

Configuring reporting method

To report test results to Datadog, you need to configure the Datadog JavaScript library:

Installing the JavaScript tracer

To install the JavaScript Tracer, run:

yarn add --dev dd-trace

For more information, see the JavaScript Tracer installation documentation.

Instrument your tests

Set the NODE_OPTIONS environment variable to -r dd-trace/ci/init. Run your tests as you normally would, optionally specifying a name for your test session with DD_TEST_SESSION_NAME:

NODE_OPTIONS="-r dd-trace/ci/init" DD_TEST_SESSION_NAME=unit-tests yarn test

Note: If you set a value for NODE_OPTIONS, make sure it does not overwrite -r dd-trace/ci/init. This can be done using the ${NODE_OPTIONS:-} clause:

package.json

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{
  "scripts": {
    "test": "NODE_OPTIONS=\"--max-old-space-size=12288 ${NODE_OPTIONS:-}\" jest"
  }
}

Adding custom tags to tests

You can add custom tags to your tests by using the current active span:

  it('sum function can sum', () => {
    const testSpan = require('dd-trace').scope().active()
    testSpan.setTag('team_owner', 'my_team')
    // test continues normally
    // ...
  })

To create filters or group by fields for these tags, you must first create facets. For more information about adding tags, see the Adding Tags section of the Node.js custom instrumentation documentation.

Adding custom measures to tests

Just like tags, you can add custom measures to your tests by using the current active span:

  it('sum function can sum', () => {
    const testSpan = require('dd-trace').scope().active()
    testSpan.setTag('memory_allocations', 16)
    // test continues normally
    // ...
  })

For more information about custom measures, see the Add Custom Measures Guide.

Mocha ECMAScript modules (ESM)

Mocha >=9.0.0 uses an ESM-first approach to load test files. Set NODE_OPTIONS to -r dd-trace/ci/init --import dd-trace/register.js to get full visibility into your tests. See dd-trace-js ESM support for more information.

Set the NODE_OPTIONS environment variable to -r dd-trace/ci/init. Run your tests as you normally would, optionally specifying a name for your test session with DD_TEST_SESSION_NAME:

NODE_OPTIONS="-r dd-trace/ci/init" DD_TEST_SESSION_NAME=e2e-tests yarn test:e2e

Note: If you set a value for NODE_OPTIONS, make sure it does not overwrite -r dd-trace/ci/init. This can be done using the ${NODE_OPTIONS:-} clause:

package.json

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{
  "scripts": {
    "test": "NODE_OPTIONS=\"--max-old-space-size=12288 ${NODE_OPTIONS:-}\" jest"
  }
}

Adding custom tags to tests

You can add custom tags to your tests by using the current active span:

test('user profile', async ({ page }) => {
  const testSpan = require('dd-trace').scope().active()
  testSpan.setTag('team_owner', 'my_team')
  // ...
})

test('landing page', async ({ page }) => {
  const testSpan = require('dd-trace').scope().active()
  testSpan.setTag('test.cpu.usage', 'high')
  // ...
})

To create filters or group by fields for these tags, you must first create facets. For more information about adding tags, see the Adding Tags section of the Node.js custom instrumentation documentation.

Adding custom measures to tests

You can also add custom measures to your tests by using the current active span:

test('user profile', async ({ page }) => {
  const testSpan = require('dd-trace').scope().active()
  testSpan.setTag('memory_allocations', 16)
  // ...
})

For more information about custom measures, see the Add Custom Measures Guide.

Playwright - RUM integration

If the browser application being tested is instrumented using Browser Monitoring, the Playwright test results and their generated RUM browser sessions and session replays are automatically linked. For more information, see the Instrumenting your browser tests with RUM guide.

Set the NODE_OPTIONS environment variable to -r dd-trace/ci/init. Run your tests as you normally would, optionally specifying a name for your test session with DD_TEST_SESSION_NAME:

NODE_OPTIONS="-r dd-trace/ci/init" DD_TEST_SESSION_NAME=integration-tests yarn test:integration

Note: If you set a value for NODE_OPTIONS, make sure it does not overwrite -r dd-trace/ci/init. This can be done using the ${NODE_OPTIONS:-} clause:

package.json

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{
  "scripts": {
    "test": "NODE_OPTIONS=\"--max-old-space-size=12288 ${NODE_OPTIONS:-}\" jest"
  }
}

Adding custom tags to tests

You can add custom tags to your test by grabbing the current active span:

  When('the function is called', function () {
    const stepSpan = require('dd-trace').scope().active()
    testSpan.setTag('team_owner', 'my_team')
    // test continues normally
    // ...
  })

To create filters or group by fields for these tags, you must first create facets. For more information about adding tags, see the Adding Tags section of the Node.js custom instrumentation documentation.

Adding custom measures to tests

You may also add custom measures to your test by grabbing the current active span:

  When('the function is called', function () {
    const stepSpan = require('dd-trace').scope().active()
    testSpan.setTag('memory_allocations', 16)
    // test continues normally
    // ...
  })

For more information about custom measures, see the Add Custom Measures Guide.

Cypress version 10 or later

Use the Cypress API documentation to learn how to use plugins for cypress>=10.

In your cypress.config.js file, set the following:

cypress.config.js

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const { defineConfig } = require('cypress')

module.exports = defineConfig({
  e2e: {
    setupNodeEvents: require('dd-trace/ci/cypress/plugin'),
    supportFile: 'cypress/support/e2e.js'
  }
})

Add the following line to the top level of your supportFile:

cypress/support/e2e.js

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// Your code can be before this line
// require('./commands')
require('dd-trace/ci/cypress/support')
// Also supported:
// import 'dd-trace/ci/cypress/support'
// Your code can also be after this line
// Cypress.Commands.add('login', (email, pw) => {})

If you’re using other Cypress plugins, your cypress.config.js file should contain the following:

cypress.config.js

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const { defineConfig } = require('cypress')

module.exports = defineConfig({
  e2e: {
    setupNodeEvents(on, config) {
      // your previous code is before this line
      return require('dd-trace/ci/cypress/plugin')(on, config)
    }
  }
})

Cypress after:run event

Datadog requires the after:run Cypress event to work, and Cypress does not allow multiple handlers for that event. If you defined handlers for after:run already, add the Datadog handler manually by importing 'dd-trace/ci/cypress/after-run':

cypress.config.js

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const { defineConfig } = require('cypress')

module.exports = defineConfig({
  e2e: {
    setupNodeEvents(on, config) {
      require('dd-trace/ci/cypress/plugin')(on, config)
      // other plugins
      on('after:run', (details) => {
        // other 'after:run' handlers
        // important that this function call is returned
        return require('dd-trace/ci/cypress/after-run')(details)
      })
    }
  }
})

Cypress after:spec event

Datadog requires the after:spec Cypress event to work, and Cypress does not allow multiple handlers for that event. If you defined handlers for after:spec already, add the Datadog handler manually by importing 'dd-trace/ci/cypress/after-spec':

cypress.config.js

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const { defineConfig } = require('cypress')

module.exports = defineConfig({
  e2e: {
    setupNodeEvents(on, config) {
      require('dd-trace/ci/cypress/plugin')(on, config)
      // other plugins
      on('after:spec', (...args) => {
        // other 'after:spec' handlers
        // Important that this function call is returned
        // Important that all the arguments are passed
        return require('dd-trace/ci/cypress/after-spec')(...args)
      })
    }
  }
})

Run your tests as you normally would, optionally specifying a name for your test session with DD_TEST_SESSION_NAME:

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DD_TEST_SESSION_NAME=ui-tests yarn test:ui

Adding custom tags to tests

To add additional information to your tests, such as the team owner, use cy.task('dd:addTags', { yourTags: 'here' }) in your test or hooks.

For example:

beforeEach(() => {
  cy.task('dd:addTags', {
    'before.each': 'certain.information'
  })
})
it('renders a hello world', () => {
  cy.task('dd:addTags', {
    'team.owner': 'ui'
  })
  cy.get('.hello-world')
    .should('have.text', 'Hello World')
})

To create filters or group by fields for these tags, you must first create facets. For more information about adding tags, see the Adding Tags section of the Node.js custom instrumentation documentation.

Adding custom measures to tests

To add custom measures to your tests, such as memory allocations, use cy.task('dd:addTags', { yourNumericalTags: 1 }) in your test or hooks.

For example:

it('renders a hello world', () => {
  cy.task('dd:addTags', {
    'memory_allocations': 16
  })
  cy.get('.hello-world')
    .should('have.text', 'Hello World')
})

For more information about custom measures, see the Add Custom Measures Guide.

Cypress - RUM integration

If the browser application being tested is instrumented using Browser Monitoring, the Cypress test results and their generated RUM browser sessions and session replays are automatically linked. For more information, see the Instrumenting your browser tests with RUM guide.

Upload test failure screenshots

When enabled, Test Optimization uploads screenshots that Cypress captures when a test fails. They appear in the Media tab of the Test Optimization test details side panel. Use them to inspect browser state at the time of failure.

To enable screenshot uploads, set the DD_TEST_FAILURE_SCREENSHOTS_ENABLED environment variable to 1. In your Cypress configuration, make sure screenshotOnRunFailure is set to true (the default).

Note: Vitest is ESM first, so its configuration is different from other test frameworks.

Use a Node.js version supported by your dd-trace major version for Vitest instrumentation:

• dd-trace v5 requires Node.js 18.19+ or Node.js 20.6+.
• dd-trace v6 requires Node.js 22 or later.

Set the NODE_OPTIONS environment variable to --import dd-trace/register.js -r dd-trace/ci/init. Run your tests as you normally would, optionally specifying a name for your test session with DD_TEST_SESSION_NAME:

NODE_OPTIONS="--import dd-trace/register.js -r dd-trace/ci/init" DD_TEST_SESSION_NAME=smoke-tests yarn test:smoke

Note: If you set a value for NODE_OPTIONS, make sure it does not overwrite --import dd-trace/register.js -r dd-trace/ci/init. This can be done using the ${NODE_OPTIONS:-} clause:

package.json

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{
  "scripts": {
    "test": "NODE_OPTIONS=\"--max-old-space-size=12288 ${NODE_OPTIONS:-}\" vitest run"
  }
}

Adding custom tags or measures to tests

You can add custom tags to your tests by using the current active span:

import tracer from 'dd-trace'
import { expect, test } from 'vitest'

test('sum function can sum', () => {
  const testSpan = tracer.scope().active()
  testSpan.setTag('team_owner', 'my_team')

  expect(1 + 2).toBe(3)
})

To create filters or group by fields for these tags, you must first create facets. For more information about adding tags, see the Adding Tags section of the Node.js custom instrumentation documentation.

You can also add custom measures to your tests by using the current active span:

import tracer from 'dd-trace'
import { expect, test } from 'vitest'

test('sum function can sum', () => {
  const testSpan = tracer.scope().active()
  testSpan.setTag('memory_allocations', 16)

  expect(1 + 2).toBe(3)
})

For more information about custom measures, see the Add Custom Measures Guide.

How to fix “Cannot find module ‘dd-trace/ci/init’” errors

When using dd-trace, you might encounter the following error message:

 Error: Cannot find module 'dd-trace/ci/init'

This might be because of an incorrect usage of NODE_OPTIONS.

For example, if your GitHub Action looks like this:

jobs:
  my-job:
    name: Run tests
    runs-on: ubuntu-latest
    # Invalid NODE_OPTIONS
    env:
      NODE_OPTIONS: -r dd-trace/ci/init
    steps:
      - name: Checkout repository
        uses: actions/checkout@v3
      - name: Install node
        uses: actions/setup-node@v3
      - name: Install dependencies
        run: npm install
      - name: Run tests
        run: npm test

Note: This does not work because NODE_OPTIONS are interpreted by every node process, including npm install. If you try to import dd-trace/ci/init before it’s installed, this step fails.

Your GitHub Action should instead look like this:

jobs:
  my-job:
    name: Run tests
    runs-on: ubuntu-latest
    steps:
      - name: Checkout repository
        uses: actions/checkout@v3
      - name: Install node
        uses: actions/setup-node@v3
      - name: Install dependencies
        run: npm install
      - name: Run tests
        run: npm test
        env:
          NODE_OPTIONS: -r dd-trace/ci/init

Follow these best practices:

• Make sure the NODE_OPTIONS environment variable is only set to the process running tests.
• Specifically avoid defining NODE_OPTIONS in the global environment variables settings in your pipeline or job definition.

Using Yarn 2 or later

If you’re using yarn>=2 and a .pnp.cjs file, you might also get the same error:

 Error: Cannot find module 'dd-trace/ci/init'

You can fix it by setting NODE_OPTIONS to the following:

NODE_OPTIONS="-r $(pwd)/.pnp.cjs -r dd-trace/ci/init" yarn test

Reporting code coverage

When tests are instrumented with Istanbul, the Datadog Tracer (v3.20.0 or later) reports it under the test.code_coverage.lines_pct tag for your test sessions.

You can see the evolution of the test coverage in the Coverage tab of a test session.

For more information, see Code Coverage.

Configuration settings

The following is a list of the most important configuration settings that can be used with the SDK.

test_session.name

Use it to identify a group of tests, such as integration-tests, unit-tests or smoke-tests.
Environment variable: DD_TEST_SESSION_NAME
Default: For dd-trace v6, the framework invocation, such as jest, mocha, playwright test, or cucumber-js. For dd-trace v5, a combination of CI job name and test command.
Example: unit-tests, integration-tests, smoke-tests

service

Name of the service or library under test.
Environment variable: DD_SERVICE
Default: (test framework name)
Example: my-ui

env

Name of the environment where tests are being run.
Environment variable: DD_ENV
Default: none
Examples: local, ci

url

Datadog Agent URL for trace collection in the form http://hostname:port.
Environment variable: DD_TRACE_AGENT_URL
Default: http://localhost:8126

For more information about service and env reserved tags, see Unified Service Tagging. All other Datadog Tracer configuration options can also be used.

Collecting Git metadata

Datadog uses Git information for visualizing your test results and grouping them by repository, branch, and commit. Git metadata is automatically collected by the test instrumentation from CI provider environment variables and the local .git folder in the project path, if available.

If you are running tests in non-supported CI providers or with no .git folder, you can set the Git information manually using environment variables. These environment variables take precedence over any auto-detected information. Set the following environment variables to provide Git information:

DD_GIT_REPOSITORY_URL

URL of the repository where the code is stored. Both HTTP and SSH URLs are supported.
Example: [email protected]:MyCompany/MyApp.git, https://github.com/MyCompany/MyApp.git

DD_GIT_BRANCH

Git branch being tested. Leave empty if providing tag information instead.
Example: develop

DD_GIT_TAG

Git tag being tested (if applicable). Leave empty if providing branch information instead.
Example: 1.0.1

DD_GIT_COMMIT_SHA

Full commit hash.
Example: a18ebf361cc831f5535e58ec4fae04ffd98d8152

DD_GIT_COMMIT_MESSAGE

Commit message.
Example: Set release number

DD_GIT_COMMIT_AUTHOR_NAME

Commit author name.
Example: John Smith

DD_GIT_COMMIT_AUTHOR_EMAIL

Commit author email.
Example: [email protected]

DD_GIT_COMMIT_AUTHOR_DATE

Commit author date in ISO 8601 format.
Example: 2021-03-12T16:00:28Z

DD_GIT_COMMIT_COMMITTER_NAME

Commit committer name.
Example: Jane Smith

DD_GIT_COMMIT_COMMITTER_EMAIL

Commit committer email.
Example: [email protected]

DD_GIT_COMMIT_COMMITTER_DATE

Commit committer date in ISO 8601 format.
Example: 2021-03-12T16:00:28Z

Manual testing API

If you use Jest, Mocha, Cypress, Playwright, Cucumber, or Vitest, do not use the manual testing API, as Test Optimization automatically instruments them and sends the test results to Datadog. The manual testing API is incompatible with already supported testing frameworks.

Use the manual testing API only if you use an unsupported testing framework or have a different testing mechanism.

The manual testing API leverages the node:diagnostics_channel module from Node.js and is based on channels you can publish to:

const { channel } = require('node:diagnostics_channel')

const { describe, test, beforeEach, afterEach, assert } = require('my-custom-test-framework')

const testStartCh = channel('dd-trace:ci:manual:test:start')
const testFinishCh = channel('dd-trace:ci:manual:test:finish')
const testSuite = __filename

describe('can run tests', () => {
  beforeEach((testName) => {
    testStartCh.publish({ testName, testSuite })
  })
  afterEach((status, error) => {
    testFinishCh.publish({ status, error })
  })
  test('first test will pass', () => {
    assert.equal(1, 1)
  })
})

Test start channel

Grab this channel by its ID dd-trace:ci:manual:test:start to publish that a test is starting. A good place to do this is a beforeEach hook or similar.

const { channel } = require('node:diagnostics_channel')
const testStartCh = channel('dd-trace:ci:manual:test:start')

// ... code for your testing framework goes here
  beforeEach(() => {
    const testDefinition = {
      testName: 'a-string-that-identifies-this-test',
      testSuite: 'what-suite-this-test-is-from.js'
    }
    testStartCh.publish(testDefinition)
  })
// code for your testing framework continues here ...

The payload to be published has attributes testName and testSuite, both strings, that identify the test that is about to start.

Test finish channel

Grab this channel by its ID dd-trace:ci:manual:test:finish to publish that a test is ending. A good place to do this is an afterEach hook or similar.

const { channel } = require('node:diagnostics_channel')
const testFinishCh = channel('dd-trace:ci:manual:test:finish')

// ... code for your testing framework goes here
  afterEach(() => {
    const testStatusPayload = {
      status: 'fail',
      error: new Error('assertion error')
    }
    testStartCh.publish(testStatusPayload)
  })
// code for your testing framework continues here ...

The payload to be published has attributes status and error:

• status is a string that takes one of three values:

  • 'pass' when a test passes.
  • 'fail' when a test fails.
  • 'skip' when a test has been skipped.

• error is an Error object containing the reason why a test failed.

Add tags channel

Grab this channel by its ID dd-trace:ci:manual:test:addTags to publish that a test needs custom tags. This can be done within the test function:

const { channel } = require('node:diagnostics_channel')
const testAddTagsCh = channel('dd-trace:ci:manual:test:addTags')

// ... code for your testing framework goes here
  test('can sum', () => {
    testAddTagsCh.publish({ 'test.owner': 'my-team', 'number.assertions': 3 })
    const result = sum(2, 1)
    assert.equal(result, 3)
  })
// code for your testing framework continues here ...

The payload to be published is a dictionary <string, string|number> of tags or measures that are added to the test.

Run the tests

When the test start and end channels are in your code, run your testing framework like you normally do, including the following environment variables:

NODE_OPTIONS="-r dd-trace/ci/init" DD_TEST_SESSION_NAME=custom-tests yarn run-my-test-framework

Known limitations

Browser tests

Browser tests executed with mocha, jest, cucumber, cypress, playwright, and vitest are instrumented by dd-trace-js, but visibility into the browser session itself is not provided by default (for example, network calls, user actions, page loads, and more.).

If you want visibility into the browser process, consider using RUM & Session Replay. When using Cypress or Playwright, test results and their generated RUM browser sessions and session replays are automatically linked. For more information, see the Instrumenting your browser tests with RUM guide.

Cypress interactive mode

Cypress interactive mode (which you can enter by running cypress open) is not supported by Test Optimization because some cypress events, such as before:run, are not fired. If you want to try it anyway, pass experimentalInteractiveRunEvents: true to the cypress configuration file.

Jest’s --forceExit

Jest’s –forceExit option may cause data loss. Datadog tries to send data immediately after your tests finish, but shutting down the process abruptly can cause some requests to fail. Use --forceExit with caution.

Mocha’s --exit

Mocha’s –exit option may cause data loss. Datadog tries to send data immediately after your tests finish, but shutting down the process abruptly can cause some requests to fail. Use --exit with caution.

Vitest’s browser mode

Vitest’s browser mode is not supported.

Vitest’s test duration overhead

By default, Vitest’s isolate option is true, so each test file runs in its own fork or thread. Vitest is ESM-first and relies on import-in-the-middle for instrumentation, which incurs a setup cost every time a suite starts. With isolation, that setup cost is repeated for every file. The effect is largest when you have many small, fast suites, because setup time can dominate wall-clock time.

To lower overhead, set isolate: false in your Vitest config file, or pass --no-isolate to the test command.

To keep Vitest isolation enabled with lower worker startup overhead, set DD_EXPERIMENTAL_TEST_OPT_VITEST_NO_WORKER_INIT=true. This option is available in dd-trace v5 (from 5.111.0) and v6 (from 6.0.0). It applies to isolated Vitest worker-pool runs with Vitest 3.2.6 and later, and falls back to normal worker instrumentation for unsupported configurations.

Because this mode does not initialize dd-trace in Vitest workers, the following features are not supported:

• Custom test tags
• Custom spans
• Log correlation from test code
• Failed Test Replay

Best practices

Follow these practices to take full advantage of the testing framework and Test Optimization.

Parameterized tests

Whenever possible, leverage the tools that testing frameworks provide for parameterized tests. For example, for jest:

Avoid this:

[[1,2,3], [3,4,7]].forEach((a,b,expected) => {
  test('sums correctly', () => {
    expect(a+b).toEqual(expected)
  })
})

And use test.each instead:

test.each([[1,2,3], [3,4,7]])('sums correctly %i and %i', (a,b,expected) => {
  expect(a+b).toEqual(expected)
})

For mocha, use mocha-each:

const forEach = require('mocha-each');
forEach([
  [1,2,3],
  [3,4,7]
])
.it('adds %i and %i then returns %i', (a,b,expected) => {
  expect(a+b).to.equal(expected)
});

When you use this approach, both the testing framework and Test Optimization can tell your tests apart.

Test session name DD_TEST_SESSION_NAME

Use DD_TEST_SESSION_NAME to define the name of the test session and the related group of tests. Examples of values for this tag would be:

• unit-tests
• integration-tests
• smoke-tests
• flaky-tests
• ui-tests
• backend-tests

If DD_TEST_SESSION_NAME is not specified, the default value is:

• For dd-trace v6, the framework invocation, such as jest, mocha, playwright test, or cucumber-js
• For dd-trace v5, a combination of the CI job name and the command used to run the tests (for example, my-ci-job yarn test)

The test session name should be unique within a repository to help you distinguish different groups of tests.

Further reading

Documentation, liens et articles supplémentaires utiles:

Forwarding Environment Variables for Tests in ContainersDOCUMENTATION Explore Test Results and PerformanceDOCUMENTATION Speed up your test jobs with Test Impact AnalysisDOCUMENTATION Troubleshooting Test OptimizationDOCUMENTATION