A method of testing an electronic device including first and second semiconductor devices connected to each other with a plurality of bus lines. First, the first semiconductor device supplies a selected one of the bus lines with a first logical output signal. Then, the second semiconductor device acquires a first bus line signal from the selected bus line. The second semiconductor device inverts the first bus line signal to generate a second logical output signal. The second semiconductor device transmits the second logical output signal to the first semiconductor device. The first semiconductor device receives a second bus line signal from the selected bus line. The first semiconductor device compares the first logical output signal and the second bus line signal to detect a connection between the first semiconductor device and the second semiconductor device.