  So far, all experimental tests of Bell inequalities which must be satisfied
by all local realistic hidden-variable theories and are violated by quantum
mechanical predictions have left at least one loophole open. We propose a
feasible setup allowing for a loophole-free test of the Bell inequalities. Two
electron spin qubits of phosphorus donors in semiconductors in different
cavities 300 m apart are entangled through a bright coherent light and
postselections using homodyne measurements. The electron spins are then read
out randomly and independently by Alice and Bob, respectively, with unity
efficiency in less than 0.7$\mu$s by using optically induced spin to charge
transduction detected by radio-frequency single electron transistor. A
violation of Bell inequality larger than 37% and 18% is achievable provided
that the detection accuracy is 0.99 and 0.95, respectively.
