Electrical Socket Doesn't Work for One Particular Appliance
The easiest thing to test with is a receptacle tester:  



But that won't find all problems, in fact there's a good chance it won't find this one.  Never decide you're safe just because a receptacle tester gives you a good indication!  Some of the problems they won't identify are dangerous.  

Even testing with a meter won't find certain problems.  This article:  

Outlet Testing Article

details the hows and whys.  It shows how a non-contact voltage tester like this one 



Can spot some dangerous problems that other methods will miss.