A test system includes a rotatable turntable, a loading section, a first image pickup section, a second image pickup section, a system control section and an unloading section. The loading section loads a display panel assembly onto the stage. The loading section recognizes a unique number of the display panel assembly. The first image pickup section obtains an active area image data from an active area image. A valid first active area defect is detected using an active area image data obtained from an active area image displayed on the display panel assembly. An inactive area defect is detected based on an inactive area image data and a reference inactive area image data.