Parallel execution configuration in Selenium Java - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of TestNG Parallel Execution Configuration

Given the following TestNG XML configuration for parallel execution, what will be the output order of test methods if each test prints its method name when run?

Selenium Java

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE suite SYSTEM "https://testng.org/testng-1.0.dtd">
<suite name="Suite" parallel="methods" thread-count="2">
  <test name="Test1">
    <classes>
      <class name="tests.SampleTest"/>
    </classes>
  </test>
</suite>

// SampleTest.java
package tests;
import org.testng.annotations.Test;
public class SampleTest {
  @Test
  public void testA() {
    System.out.println("testA");
  }
  @Test
  public void testB() {
    System.out.println("testB");
  }
  @Test
  public void testC() {
    System.out.println("testC");
  }
}

A testA\ntestB\ntestC (order may vary but all run concurrently with max 2 threads)

B testA\ntestB\ntestC (always sequential in this order)

C testA\ntestC\ntestB (always this fixed order)

D Only testA runs because thread-count limits to 1

💡 Hint

Parallel execution with thread-count=2 means up to 2 tests run at the same time, order is not guaranteed.

With parallel="methods" and thread-count=2, TestNG runs up to 2 test methods simultaneously. The order of printed output can vary because tests run concurrently, but all tests will run.

❓ assertion

intermediate

Correct Assertion for Parallel Test Execution Completion

In a Selenium TestNG parallel test suite, which assertion correctly verifies that all tests have completed execution before proceeding?

Selenium Java

import org.testng.Assert;
import org.testng.annotations.Test;

@Test
public void verifyAllTestsCompleted() {
  boolean allTestsDone = TestExecutionListener.allTestsFinished();
  // Which assertion below is correct to confirm all tests finished?
}

A Assert.assertFalse(allTestsDone, "Not all tests completed");

B Assert.assertNull(allTestsDone, "Not all tests completed");

C Assert.assertTrue(allTestsDone, "Not all tests completed");

D Assert.assertEquals(allTestsDone, false, "Not all tests completed");

💡 Hint

You want to confirm the boolean flag is true indicating completion.

The variable allTestsDone is true when all tests finish. Assert.assertTrue checks this condition correctly.

🔧 Debug

advanced

Debugging Thread Safety Issue in Parallel Selenium Tests

You have configured parallel execution in TestNG with thread-count=3. Your Selenium tests share a WebDriver instance stored in a static variable. What problem will most likely occur?

A Tests will throw a compilation error due to static WebDriver.

B Tests will run faster without any issues because WebDriver is shared.

C Tests will run sequentially ignoring parallel configuration.

D Tests will fail intermittently due to WebDriver instance conflicts across threads.

💡 Hint

Consider thread safety when sharing objects in parallel tests.

Sharing a single WebDriver instance across multiple threads causes conflicts and unpredictable failures because WebDriver is not thread-safe.

❓ framework

advanced

Best Practice for Parallel Execution in Selenium with TestNG

Which TestNG suite XML configuration snippet correctly enables parallel execution at the class level with 4 threads?

A

<suite name="Suite" parallel="classes" thread-count="4">
  <test name="Test">
    <classes>
      <class name="tests.TestClass1"/>
      <class name="tests.TestClass2"/>
    </classes>
  </test>
</suite>

B

<suite name="Suite" parallel="tests" thread-count="4">
  <test name="Test1">
    <classes>
      <class name="tests.TestClass1"/>
    </classes>
  </test>
  <test name="Test2">
    <classes>
      <class name="tests.TestClass2"/>
    </classes>
  </test>
</suite>

C

<suite name="Suite" parallel="methods" thread-count="4">
  <test name="Test">
    <classes>
      <class name="tests.TestClass1"/>
      <class name="tests.TestClass2"/>
    </classes>
  </test>
</suite>

D

<suite name="Suite" parallel="instances" thread-count="4">
  <test name="Test">
    <classes>
      <class name="tests.TestClass1"/>
      <class name="tests.TestClass2"/>
    </classes>
  </test>
</suite>

💡 Hint

Parallel at class level means parallel="classes" in suite tag.

Setting parallel="classes" with thread-count=4 runs test classes in parallel with up to 4 threads.

🧠 Conceptual

expert

Impact of Parallel Execution on Test Data Management

In a Selenium TestNG suite running tests in parallel, what is the best approach to manage test data to avoid flaky tests?

A Share a single global data object across all tests to reduce memory usage.

B Use thread-local storage or separate data instances per test thread to isolate test data.

C Load test data once before suite and reuse it without synchronization.

D Use static variables to store test data accessible by all threads.

💡 Hint

Think about data isolation in parallel environments.

Sharing data without isolation causes race conditions and flaky tests. Using thread-local or separate data per thread ensures test independence.