Comment 2 for bug 1784755

See branch: home/cparker/drc_test

Current state of things:
There is currently a large series of tests for polygon clearance, minimum sizes and minimum spacings in the pcb/tests/inputs directory. These are intended to capture the current state of the DRC, and have not yet been vetted to determine if there are actual errors that are or aren't being flagged.

After a conversation with Peter C., he suggested a number of additional cases that ought to be tested, such as rotated objects, and objects that clear just the edges of polygons. I've starting working on a python script to rebuild all of these tests automatically to make adding adjustments easier, see branch home/cparker/test_tools, however, it might be easier to just do some of it by hand.

Here are some of my notes from my conversation with him:

* Check arcs with different arc spans, 45, 180, 270.
* Thermals??
* Polyclearance, PWL
* Also try everything at 45 deg.
* Try testing for objects off the board?
* Should we warn the user if a line clearance is less than the global clearance requirement?
* There is a difference between completely interior objects and partially interior objects.
* Items inside polygon holes
* Format specifiers that eat multiple arguments? Fewer format specifiers.
* minimum copper polygon between two objects.
* necking down like busses coming together.
* corners?
* Pad case doesn't clear edge of polygon?
* Try outer edge case with the clearline flag off.