This demo presents DTS (software defects testing system), a tool to catch defects in source code using static testing techniques. In DTS, various defect patterns are defined using defect patterns state machine and tested by a unified testing framework. Since DTS externalizes all the defect patterns it checks, defect patterns can be added, subtracted, or altered without having to modify the tool itself. Moreover, typical interval computation is expanded and applied in DTS to reduce the false positive and compute the state of defect state machine. In order to validate its usefulness, we perform some experiments on a suite of open source software whose results are briefly presented in the last part of the demo.