I was amazed initially when I saw this type of issue in Eclipse. I imported one of my Selenium based functional automation project and installed TestNG. I pointed my cursor on testng.xml and hit mouse right click on it. I was surprised to see blank menu. I did this couple of times after restarting, reinstalling the eclipse but nothing worked for me.
Initially, JRE6 was installed on my system. I installed jre1.8.0_45 and I later realized that I did not set JAVA_HOME & PATH in environment variables. After doing so and restarting eclipse, I didn't face this issue anymore.