Test device for display panel and method of testing the same

A test device for a display panel, comprising:

• a luminance measurement unit configured to measure a luminance value of the display panel comprising a plurality of pixels;
• and
• a controller configured to determine a voltage value of a data signal corresponding to a target luminance value, to receive a measured luminance value of a pixel to which the data signal is supplied from the luminance measurement unit from among the plurality of pixels, configured to compare the measured luminance value and the target luminance value, to correct the voltage value of the data signal until the measured luminance value coincides with the target luminance value, configured to output a control signal, after the measured luminance value coincides with the target luminance value, that changes a first power source voltage value supplied from a power source voltage supply unit to the pixel until the measured luminance value does not coincide with the target luminance value, and configured to set, as an output first power source voltage value, the first power source voltage value used immediately before the controller determines the measured luminance value does not coincide with the target luminance value.