That's my point and what I have argued the whole time. All they have to do is provide some test vectors and run them on the chip tester. This is common practice and quick and pretty cheap (even though you pay for tester time). And then why not do it properly and do scan insertion and ATPG to cover the other parts which is pretty much standard procedure in the industry these days.
Well, as I thought:
Office Space 2 will have a character named
Milton the test collator who will constantly mumble "scan insertion", "ATPG", etc.
But here's the usefull information for the future. Yield in semiconductor industry is defined as a percentage of the dies that are "good" as opposed to "faulty". The decision between good/bad is binary only when the die contains a single circuit. It obviously applies to a CPU or a similar chip, because such a device contains a JTAG chain that is essentially threading through the every flip/flop on the chip. So if a defect breaks the JTAG chain the die becomes untestable and it isn't even worth to package it.
In the Bitcoin mining ASIC realm currently only ASICminer and Avalon have a single-engine dies. So those are the only two vendors that could conceivably use "yield" as a single percentage value.
Every other Bitcoin mining vendor have multi-engine dies: BFL has 16, bitfury has 756. To make such a chip "fail" you'll have to either kill their control logic or kill all the engines. In all other cases the chip is neither "good" nor "bad", but has some "inbetween" value that is neither 0% nor 100%.
KnC went one step ahead and their die consists of 48 engines and 4 completely independent "control logic" and "power supply" circuits. To make such a chip "fail" you'll have to e.g. kill all 4 contol logic cicuits or 3 control circuts and all 12 engines in the quadrant with the working control logic. If you kill only 11 engines in the "good" quadrant your resulting chip is 2.08% "good" and still has more performace than the 100% "good" Avalon chip.
Semiconductor manufacturing plants are prepared to deal with both types of "yield": the binary "pass/fail" type and the contiguous "quality curve" type. The problem is that the "quality curve" testing is complex and expensive, and therefore used only for the analog or mixed-signal devices. The "pass/fail" test is indeed cheap and quick and it is used for the vast majority of digital devices. But the Bitcoin mining ASIC is a completely atypical digital device therefore applying even a very cheap pass/fail test to it is economically pointless.
I've typed all this because I hope this will be usefull for the readers not well-versed in the electroinic engineering. I don't hope to sway
Milton the tester's kingcoin's opinion, but I presume that the concern trolls will like him will keep poping up on this forum for many months, until the ways to characterize yield and test Bitcoin ASIC will become a common knowledge and will move from this subforum to the mining software subforum.