lambdatest-automate

lambdatest-automate

Overview

LambdaTest is a newer cloud-grid provider with strong real-device coverage + Visual UI testing add-ons. Like BrowserStack + Sauce Labs, it exposes a W3C-compliant endpoint.

Per lambdatest.com/support/docs/automated-web-testing (Cloudflare-protected; cite by stable URL).

Composes with browser-matrix-strategy-reference; routed via selenium-grid-orchestrator.

When to use

• Cross-browser regression with LambdaTest as the chosen grid.
• Visual regression via LambdaTest's SmartUI (alternative to Percy / Chromatic in qa-visual-regression).
• Internal-network apps via LambdaTest Tunnel.
• Cost-comparison against BrowserStack / Sauce.

Authoring

Authentication

export LT_USERNAME="your-username"
export LT_ACCESS_KEY="<access-key>"

Hub URL

https://hub.lambdatest.com/wd/hub

Capabilities (W3C)

{
  "browserName": "Chrome",
  "browserVersion": "latest",
  "platformName": "Windows 11",
  "LT:Options": {
    "user": "$LT_USERNAME",
    "accessKey": "$LT_ACCESS_KEY",
    "build": "PR-1234",
    "name": "Login flow on Chrome Windows",
    "project": "my-app",
    "selenium_version": "4.21.0",
    "w3c": true,
    "console": "info",
    "network": true,
    "video": true,
    "visual": true,
    "tunnel": false,
    "tunnelName": "my-tunnel",
    "smartUI.project": "my-smartui-project"
  }
}

LT:Options carries LambdaTest-specific:

Option	Purpose
user / accessKey	Credentials (alternative to env vars)
build	CI build / PR identifier
name	Session label
project	Group sessions by project (dashboard)
selenium_version	Pin Selenium version
w3c	Enable W3C mode (default true)
console	Console-log level: "errors" / "warnings" / "info" / "verbose"
network	Capture HAR file
video	Session recording
visual	Per-step screenshots
tunnel / tunnelName	LambdaTest Tunnel for internal apps
smartUI.project	Link to SmartUI visual-regression project

Python example

import os
from selenium import webdriver

caps = {
    "browserName": "Edge",
    "browserVersion": "latest",
    "platformName": "Windows 11",
    "LT:Options": {
        "user": os.environ["LT_USERNAME"],
        "accessKey": os.environ["LT_ACCESS_KEY"],
        "build": os.environ.get("BUILD_TAG", "local"),
        "name": "Checkout on Edge",
        "project": "my-app",
        "console": "errors",
        "network": True,
        "video": True,
    },
}

driver = webdriver.Remote(
    command_executor="https://hub.lambdatest.com/wd/hub",
    options=webdriver.EdgeOptions(),
)
for k, v in caps.items():
    driver.capabilities[k] = v

driver.get("https://example.com")
# test...
driver.quit()

Running

Report session status

driver.execute_script(
    "lambda-status=" + ("passed" if not failed else "failed")
)

LambdaTest's JS executor pattern is "lambda-<command>=...".

LambdaTest Tunnel

For internal-network apps:

# Download from lambdatest.com/support/docs/lambda-tunnel
./LT --user $LT_USERNAME --key $LT_ACCESS_KEY --tunnelName "my-tunnel"

Then set LT:Options.tunnel: true and tunnelName: "my-tunnel".

SmartUI integration

LambdaTest SmartUI handles visual regression alongside the functional test:

driver.execute_script("smartui.takeScreenshot=login-page")

Smart screenshots compare against a baseline; differences flagged in the SmartUI dashboard. See qa-visual-regression for visual-regression discipline.

Parsing results

LambdaTest session reports:

• Session video (video: true)
• Network HAR (network: true)
• Browser console logs (console: "verbose")
• Per-step screenshots (visual: true)
• SmartUI diffs (if SmartUI configured)

REST API:

curl -u "$LT_USERNAME:$LT_ACCESS_KEY" \
  "https://api.lambdatest.com/automation/api/v1/sessions/<session-id>"

CI integration

on: pull_request
jobs:
  lambdatest:
    runs-on: ubuntu-latest
    strategy:
      matrix:
        browser:
          - { name: Chrome, version: latest, platform: "Windows 11" }
          - { name: Firefox, version: latest, platform: "Windows 11" }
          - { name: Safari, version: "17", platform: "macOS Sonoma" }
    steps:
      - uses: actions/checkout@v5
      - name: Run on LambdaTest
        env:
          LT_USERNAME: ${{ secrets.LT_USERNAME }}
          LT_ACCESS_KEY: ${{ secrets.LT_ACCESS_KEY }}
          LT_BROWSER: ${{ matrix.browser.name }}
          LT_VERSION: ${{ matrix.browser.version }}
          LT_PLATFORM: ${{ matrix.browser.platform }}
          BUILD_TAG: pr-${{ github.event.pull_request.number }}
        run: pytest tests/e2e/ --lambdatest

Anti-patterns

Anti-pattern	Why it fails	Fix
Confusing tunnel (boolean) with tunnelName (string)	Tunnel won't activate	Set both when using tunnel
Missing project field	Dashboard organisation suffers	Always set project
Default w3c: false (old mode)	W3C parity issues; future versions remove non-W3C	Always set w3c: true (default)
Polling for tunnel ready without timeout	Test suite hangs	Bounded wait
Hardcoded LambdaTest URL in tests	Switching grids requires code changes	Abstract via env-var-driven config
SmartUI baseline never approved	False positives flood reports	Approve initial baseline; audit changes
Treating LambdaTest as drop-in replacement for BrowserStack	Caps shape differs (LT:Options vs bstack:options)	Use a small abstraction layer in test harness

Limitations

• Smaller real-device matrix than BrowserStack. Device coverage improving but still less broad.
• Visual UI testing is paid add-on. SmartUI requires additional licensing.
• Less mature documentation. Some edge cases (specific browser versions, mobile-real-device-only features) have thinner docs than competitors.
• Pricing model differs. Per-parallel-session vs per-minute; cost analysis depends on workload shape.

References

• LambdaTest automated web testing - lambdatest.com/support/docs/automated-web-testing.
• LambdaTest capabilities generator - lambdatest.com/capabilities-generator.
• LambdaTest Tunnel docs - lambdatest.com/support/docs/lambda-tunnel.
• W3C WebDriver specification - w3.org/TR/webdriver2/.
• Composes: browser-matrix-strategy-reference.
• Sibling skills: browserstack-automate, saucelabs-automate, selenium-grid-4-runner.
• Routed by: selenium-grid-orchestrator.