To run them together there are few options available but I have chosen using different profiles for Junit and TestNG. But now problem is with excluding and including test c
Simplest solution is like this
maven-surefire-plugin ${surefire.version} org.apache.maven.surefire surefire-junit47 ${surefire.version} org.apache.maven.surefire surefire-testng ${surefire.version}
More info about this: Mixing TestNG and JUnit tests in one Maven module – 2013 edition