I had faced somesame problem because I downloaded TestNG plugin from Eclipse. Here what I did to get the Job done :
After adding TestNG to your project library create one folder in your Project names as lib ( name can be anything ) :
Go to "C:\Program Files\Eclipse\eclipse-java-mars-R-win32-x86_64\eclipse\plugins" location and copy com.beust.jcommander_1.72.0.jar and org.testng_6.14.2.r20180216145.jar file to created folder (lib).
Note : Files are testng.jar and jcommander.jar
- Now Launch CMD, and navigate to your project directory and then type :
Java -cp C:\Users\User123\TestNG\lib*;C:\Users\User123\TestNG\bin org.testng.TestNG testng.xml
That's it !
Let me know if you have any more concerns.