The figure below shows $2000$ points in $(x,y)$ coordinates that are supposed to be high quality pseudorandom numbers.
However, when I zoom in on any area lots of points are lined up along line segments, and there are relatively large areas with no points. This is illustrated in the next figure where I drew red lines to show where some of them are arranged in a short line. I also drew ellipses where there are larger gaps.
Does this look like high quality pseudorandom numbers? What quatitative tests can be used to verify or disprove my hypothesis?