Recently testing of Quantum-dot Cellular Automata (QCA) Circuits has attracted a lot of attention. In this paper, QCA is investigated for testable implementations of reversible logic. To amplify testability in Reversible QCA circuits, a test method regarding to Built In Self Test technique is developed for detecting all simulated defects. A new Reversible QCA MUX 2×1 design is proposed for the test layer implementation regarding to overhead and power savings. Our proposed Reversible QCA MUX 2×1 design resulted in decrease in QCA cell counts and minimal input to output delay. The proposed design is simulated and verified using QCA Designer ver.2.0.3.