The present invention provides an array substrate, which includes a plurality of pixel units, each pixel unit includes a thin film transistor, a pixel electrode, a common electrode and a passivation layer, the thin film transistor includes an active layer, a gate electrode, a source electrode and a drain electrode, the drain electrode and the pixel electrode are connected, the passivation layer is disposed on the active layer, the source electrode, the drain electrode and the pixel electrode, the common electrode is disposed above the pixel electrode with the passivation layer therebetween, a test electrode is disposed on the active layer and under the passivation layer, the test electrode is electrically insulated from the gate electrode, the source electrode and the drain electrode. Correspondingly, a method for fabricating and a method for testing the array substrate, and a display device including the array substrate are provided.