Some examples:

1. test = foo("bar"); 
2. test = foo("bar\"");
3. test = foo("bar") + bar("foo");
4. test = foo("bar\"") + bar("foo");

I use: /foo\((")(.*)([^\\\])"\)/')/
Works for 1 and 2, but fails on 3 and for shouldn't match the + bar(...) part but is does.