The //* /*/ //*/ comment toggle trick
DON'T DO THIS!<p>When your code base grows you will end with dozens of places to change your code, all of them error prone. More things you need to keep control means more potential problems.<p>There are 2 alternatives to this. For languages that have macros (C#, C, C++) use the #ifdef construct, as others suggested here. For languages that don't have them (Java, Perl) use a less error prone alternative:<p>static boolean Test = false; // Only one place to change code<p>...<p>if(Test) doTest();<p>The difference in this last technique is that since you have just one place to change code there is less chance for errors and the change is easier to automate.