A test structure and a method for fabricating the same are disclosed. The test structure includes a plurality of sampling lines over a substrate located between a plurality of a first grounding lines and a plurality of a second grounding lines. The sampling lines are selectively electrically coupled to the first grounding line or the second grounding line and include at least one programmed defect. A double-patterning fabricating approach is utilized to produce such test structure which may be applied to a charged particle beam such as an electron-beam defect inspection system.