Run Selenium tests in parallel on multiple browsers

This blog is follow up from my previous one where I worked out an example to take screenshots on test failure. In this blog I am going to attempt to run the same tests however on multiple browsers and in parallel.


To achieve multi-browser parallel run of the test cases:

• I have updated the testng.xml and added config to run the tests in parallel with browser_type parameters each with its own thread, one for firefox and one for chrome.
• Updated pom.xml to start using testng.xml file to kickoff the test cases.
• Updated WebDriverManager class to be thread aware and return correct WedDriver (Firefox or Chrome) instance so that in case of test failure screenshot of correct browser can be taken.
• Minor tweak in the test case so that its aware of which browser type to run with.

The entire project is uploaded on github for reference: https://github.com/njaiswal/council-tax-band

Right, lets get to the nuts and bolts now.

testng.xml

Two test cases in the suite, TestNG will run these 2 test case with a threadpool size of 2, which means that both browsers will fire-up at almost the same time and go through the test cases in parallel which saves us time!

pom.xml (snippet)

Above pom.xml snippet tells maven to start using testng.xml to kick off the test cases. Please refer full pom.xml on github

WebDriverManager

WebDriverManager is a bit more meaty than previous blog. Instead of keeping the WebDriver instance as static variable it has a static HashMap in which it will store thread Id as the key and the WebDriver instance as value. Since our tests are now going to run on more than 1 thread we need this arrangement so that WebDriverManager knows which instance to return to onTestFailure() method based on the Thread Id.

CTaxBandTest (snippet)

As you can see above I have used the @Parameters annotation along with @BeforeClass. This basically fetches parameter browser_type from the testng.xml file and passes it as method parameter to onTimeSetUp() method. This is a key step where we call WebDriverManager.startDriver() and get correct browser instance created. As mentioned above, WebDriverManager will store the instance reference in a HashMap with thread Id as key so that any future calls to WebDriverManager.getDriverInstance() can identify which browser instance to return.

Reports

Run the tests using 'mvn test' command and you should see 2 browser instances (Firefox and Chrome) getting started at the same time and the tests being run in parallel. 

Two reports get generated (one for each browser type) with total of 4 test cases being run and more importantly both contain correct screenshots of test failures.

Again the entire project is on git hub for reference, happy testing!