Earlier quoted context omitted.
What's so bad about a grammar test? Any competent person (excluding extenuating circumstances: dyslexia, etc.) should be able to pass a simple grammar test. It's not some hardship that you have to study for or anything.
It's more like I am applying for a programming job, and I don't see why I have to subject myself to your whims. Consider that instead of grammar, I am advocating I will only hire people who can do 50 push-ups. After all, what can I expect from people who are sloppy towards something as important their own bodies. What's so bad about 50 push-ups? Any fit person(excluding extenuating circumstances) should be able to do…
In some hires I've used a descriptive writing assignment, where I ask the candidate to describe in words what they are looking at. You can learn much from these things, including: analysis skills, close looking, how they think, and, well, how well they would document their software.