How to run parallel tests with TestNG?

How can I run parallel tests with TestNG?

Hello Macy,

Below is a sample XML file which would help you to run a single test on various browsers at the same time. You would also need to generate a test case which makes use of TestNG framework parameters (org.testng.annotations.Parameters).

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE suite SYSTEM "http://testng.org/testng-1.0.dtd">
<suite thread-count="3" name="LambaTestSuite" parallel="tests">

  <test name="WIN8TEST">
  <parameter name="browser" value="firefox"/>
  <parameter name="version" value="62.0"/>
  <parameter name="platform" value="WIN8"/>
    <classes>
      <class name="LambdaTest.TestNGToDo"/>
    </classes>
  </test> <!-- Test -->

  <test name="WIN10TEST">
  <parameter name="browser" value="chrome"/>
  <parameter name="version" value="79.0"/>
  <parameter name="platform" value="WIN10"/>
    <classes>
      <class name="LambdaTest.TestNGToDo"/>
    </classes>
  </test> <!-- Test -->
  <test name="MACTEST">
  <parameter name="browser" value="safari"/>
  <parameter name="version" value="11.0"/>
  <parameter name="platform" value="macos 10.13"/>
    <classes>
      <class name="LambdaTest.TestNGToDo"/>
    </classes>
  </test> <!-- Test -->

</suite>