[R] How to find statistics like that.

[Gao Fay]

Hi there,

Suppose mu is constant, and error is normally distributed with mean 0 and 
fixed variance s. I need to find a statistics that:
Y_i = mu + beta1* I1_i beta2*I2_i + beta3*I1_i*I2_i + +error, where I_i is 
1 Y_i is from group A, and 0 if Y_i is from group B.

It is large when  beta1=beta2=0
It is small when beta1 and/or beta2 is not equal to 0

How can I find it by R? Thank you very much for your time.
Fay