A method of testing a display panel including a pixel coupled to first, second, and third power lines, a data line, scan lines, an emission control line, and a test line, the method includes: applying a first power supply voltage to the first power line; applying a test voltage having a turn-on voltage level to the second power line; applying a scan signal having a turn-on voltage level sequentially to the scan lines and an emission control signal having a turn-on voltage level to the emission control line; applying a gate signal to the test line to turn on a test transistor coupled between two electrode of a light emitting element included in the pixel; measuring a sensing voltage output through the data line; and determining whether the pixel is defective, based on a voltage level of the measured sensing voltage.