There is no direct way to install TestNG from eclipse marketplace from versions Eclipse 2019-03 (4.11). On popular request, I am writing this article, making life lot easier than copying local version of TestNG zip folder route. I hope this will help you, write me if you have any questions or problems in the walk through.
This method works for all versions of Eclipse, especially for the newer versions which does not allow installation of TestNG in marketplace.
Eclipse 2020-03 R
Eclipse 2019-12 (4.14)
Eclipse 2019-09 (4.13)
Eclipse 2019-06 (4.12)
Eclipse 2019-03 (4.11)
Navigate to Help \ Install New Software...
In the install dialog box, enter following url and hit enter
Select TestNG from the list, click Next and follow the installation wizard all the way to finish the installation procedure
Now we will have TestNG plugin installed to IDE.
Run Configuration
New TestNG Class
TestNG in project context menu