I've made a plan of APU tests to write; my focus will be on things that can't be easily verified in other ways. After I've made a fairly comprehensive set and they've been tested here, I'll put them together in a package submit them to the main NesDev catalog.
Here are two more tests:
http://h1.ripway.com/blargg/temp/test_apu_length.zip - Tests length counter control and status ($4015) operation, halt, and all 32 table entries for each channel.
http://h1.ripway.com/blargg/temp/test_apu_timers.zip - Does basic test of each channel's frequency timer for off-by-one errors, and checks DMC frequency table.
I'll probably cover the frame counter ($4017) and the triangle's linear counter next.
Here are two more tests:
http://h1.ripway.com/blargg/temp/test_apu_length.zip - Tests length counter control and status ($4015) operation, halt, and all 32 table entries for each channel.
http://h1.ripway.com/blargg/temp/test_apu_timers.zip - Does basic test of each channel's frequency timer for off-by-one errors, and checks DMC frequency table.
I'll probably cover the frame counter ($4017) and the triangle's linear counter next.