1. Web Performance Testing
with WebDriver
An integrated approach
Michael Klepikov
Make the Web Faster Team, Google
developers.google.com/speed
webpagetest.org

2. ■ +1s load => -7% conversion rate
■ Just better user experience
■ Mobile exacerbates slowness
■ 46% mobile users abandon after 10s
Why is it important?

3. ■ WebPageTest.org
■ Waterfall chart
■ Simulated latency
■ Many iterations for statistical validity
Page Load performance

4. Interactive scenarios
■ Multi-page
■ Login
■ Placing an order
■ AJAX is a better user experience

5. Test Systems Integration
■ WebPageTest is a separate system
■ Everyone has a custom toolchain
■ Hard to integrate
■ Not a seamless developer experience

6. ■ Standard WD API:
○ Session Capabilities
○ Logging
■ Easy to enable in existing tests
■ Fits well into existing toolchains
Build it into WebDriver itself

7. ■ LoggingPreferences
in WD capabilities
// Ask Chrome to collect "performance" log
DesiredCapabilities caps = DesiredCapabilities.chrome();
LoggingPreferences logPrefs = new LoggingPreferences();
logPrefs.enable("performance", Level.INFO);
caps.setCapability(CapabilityType.LOGGING_PREFS, logPrefs);
driver = new RemoteWebDriver("http://localhost:9515", caps);
WD API: Create Driver

8. ■ Plain functional test, nothing special
■ Free magic for developers!
■ Pro tip: console.time()+timeEnd(), timeStamp()
driver.get("http://www.google.com/");
WebElement element = driver.findElement(By.name("q"));
element.sendKeys("GTAC 2013");
element.submit();
WD API: Run Test

9. ■ Not part of test per se, inject:
○ In tearDown()
○ Override WebDriver.quit()
○ WebDriver HTTP-JSON proxy
log = driver.manage().logs().get("performance").getAll();
for (LogEntry entry : log) {
// WebDriver LogEntry message is a JSON string
JSONObject m = new JSONObject(entry.getMessage());
... m.getString("webview") ... // Originating WebView id
... m.getJSONObject("message") ... // Raw DevTools event
WD API: Get Performance Log

10. Performance Analysis

11. Demo
https://gist.github.com/klepikov/5457750

12. ■ No WD within instrumented intervals
■ Aggregate over multiple iterations!
■ Run frontend in maximum isolation
○ Mock/stub/fake backends
■ Use WebPageReplay
Stable Repeatable Results