In the near future the era of Beyond CMOS will start as the scaling of the current CMOS technology will reach the fundamental limit. QCA (Quantum-dot Cellular Automata) is the transistor less computation paradigm and viable candidate for Beyond CMOS device technology. The complete state of art survey on QCA is presented in this paper. This paper addresses the QCA background, its possible implementation and available simulation and synthesis tools. In depth survey is carried out for the QCA oriented defects and testing. Also, need of development and possible research areas in various sides of QCA are discussed.