How to Test a Module dat is dependent on othr

[Sandeep Singh]

Hi All.
Can Any body tell me how to test any module that is itself dependent on other modules.
For example.
i have class A having module named aProc().
And suppose aProc() makes a call to any module declared in other class, lets say B.
as
class A
{
//...
bool aProc()
{
B b;
if ( b.bProc()) // Call to B class' function
{
  // DO SOMETHING
}
else
{
    //DO SOMETHING
}

}

So here in Class A aProc() is dependent on b.bProc()'s output.
So my question is that do i need to make a TestSuits for class B also along with class A.
Remember i want to unit test only Class A and not B.

Regards,
Sandeep.