This little piece of software can barely be called a test. But still, it is suited for spotting pixel errors.
When looking for pixel errors, it is best to just fill the screen with one homogeneous color. TFT-Test offers the colors white, red, green, blue and black. In case you should spot any small dots on the screen, you are dealing with pixel errors. It is recommended to clean the entire screen so that there are no dust particles on it prior to performing this test. Dust particles can reflect the light of the monitor and be mistaken for pixel errors.
You can download TFT test here.