How to acess another member class object from within class

Im relatively new to cpp. Im currently trying to write new testcases for a class foo,

Class foo2 { 
Public:
 Getsomevariable();
 // do something
}

Class foo {
Private:
Foo2 foo2_obj;
}

Now Im testing using object of foo, but how should I be able to access foo2.Getsomevariable() from foo object?

Please help