1. A driver assistance system for a vehicle, said driver assistance system comprising: a camera configured to be disposed at a vehicle equipped with said driver assistance system; wherein said camera, when disposed at the equipped vehicle, views through a windshield of the equipped vehicle; wherein said camera is disposed at a windshield electronics module attached at the windshield of the equipped vehicle; wherein said camera views forwardly through the windshield of the equipped vehicle at a location that is swept by a windshield wiper of the equipped vehicle; said camera capturing image data of a scene forward of the equipped vehicle; a controller comprising an image processor; said image processor processing captured image data; wherein said controller, responsive to said image processor processing captured image data, detects an object of interest external to the vehicle; wherein said image processor, when processing captured image data, utilizes a blockage detection algorithm to detect at least a partial blocking condition at said camera; wherein said controller determines a driving condition of the vehicle; wherein, responsive to determination of a driving condition that is indicative of end of line vehicle testing of the vehicle at a vehicle assembly plant, and responsive to said image processor processing captured image data and said image processor utilizing said blockage detection algorithm, said image processor detects at least a partial blocking condition at said camera; and wherein, during the determined end of line vehicle testing of the vehicle at the vehicle assembly plant and with the vehicle driven on rollers to check engine performance, said controller ignores the detected partial blockage condition at said camera.