I am assuming this test was administered in the US, given that they seem to have used addresses in American cities.
In the US, the relevant law governing hiring is the Americans with Disabilities Act of 1990. As far as employment is concerned, the main enforcing body is the Equal Employment Opportunity Commission. This is what the EEOC has to say about testing: the ADA "makes it unlawful to use employment tests that screen out or tend to screen out an individual with a disability or a class of individuals with disabilities unless the test, as used by the employer, is shown to be job-related and consistent with business necessity." Employers are obliged "to make reasonable accommodations, including in the administration of tests, to the known physical or mental limitations of an otherwise qualified individual with a disability who is an applicant or employee, unless such accommodation would impose an undue hardship."
What constitutes a "reasonable accommodation" is defined by case law, but it goes beyond the mere convenience of an employer or the ability to do a task at the maximal speed. For instance, the Law School Admissions Council has been compelled to provide extra time, readers, scribes, etc. for people with relevant disabilities; and courts ruled against UPS for having a more stringent policy on driver hearing than is required by the Department of Transportation. If an accommodation--as simple as having a second person double-check the CNC codes, which would seem like a pretty obvious practice for anyone, regardless of dyslexia (something about 'measure twice, cut once'?)--would mean that the candidate could do the job, then it would be discriminatory to exclude that candidate on the basis of dyslexia. Or to use a test that tends to disqualify people who could be successful employees with accommodation.
Moreover, given that sources as diverse as the Houston Chronicle, Indeed.com, study.com, and books on living with dyslexia specifically call out "machinist" as a good career for people with dyslexia--one at which people with dyslexia may even excel due to being visually-oriented reasoners--claims from commenters here that dyslexia would disqualify you for employment as a machinist are not credible.
All of which is to say, it sounds like this test did have a discriminatory impact, which is in conflict with the language of the law and the enforcement pattern. (Though only the courts can actually decide in any individual case.)
And that's what it comes down to in the answer to your question. The law's the law, but what matters is what you can get enforced; and it can be years, even if you win.
If you want, it would not be unreasonable at this point to talk with the local EEOC office about the situation you experienced. I wouldn't expect much from it, but what do you have to lose? The test administrators probably did not specifically intend to discriminate against you, or people with dyslexia generally, so much as just being ignorant of their legal obligations. From the perspective of the law, this does not matter. That said, if it were me, I would not complain to the company directly at this point, because it would only give them the opportunity to come up with an alternate excuse as to why you were not hired, if there actually were an investigation.
For next time, what you should do going forward is to be ready to respond immediately. You've learned something from this interview: this kind of discriminatory testing exists and you might have to address it. It sucks and it's unreasonable that you should have to do this, but more preparation will maximize your chances of success. I would suggest:
- Have a specific set of criteria for what questions would prompt you to ask for an accommodation. Write them out so they're clear to you, though you don't necessarily need to bring them to the interview.
- Have specific accommodations in mind that seem reasonable and appropriate to you. Again, write them out, though it's up to you if you want to have the written copy in your back pocket.
- Prepare a script for how you would explain the situation and ask for the accommodation. This will make you more confident, clearer, and less awkward.
- Speak with a doctor in advance and get some sort of documentation that you could provide on the spot if challenged. I'm thinking a letter diagnosing your dyslexia and describing the specific kinds of tasks that are disproportionately challenging (e.g. recognizing transposed letters, but not numbers, etc.)
- Then, next time you see a discriminatory test, go ahead and ask for that accommodation.
Don't bring it up unless you have to. But when you encounter something testing you unfairly like this, you'll be prepared to say something like:
I don't like to bring attention to it if I don't need to, but I have dyslexia. As a result of this medical condition, questions like [SPECIFIC QUESTION EXAMPLE] are disproportionately challenging for me, and I am concerned that this test won't accurately reflect the skills and capabilities I would bring to this job. Is there a more directly job-relevant way I can demonstrate my skills for you? [You could offer to go over some CNC code with them if that's in your skill set, etc.; the goal is a) to show them you want to work and want to show it in a very job-relevant way and b) remind them that they have an obligation to accommodate you, but simultaneously seem helpful in giving them a solution for how to do that.] Alternatively, could I ask that you omit this section of the test from my evaluation/give me extra time on this section/[other accommodation option you've thought of beforehand]?
This would also be a good opportunity to segue into some of the ways your coping strategies have helped you be a better employee and a good influence on your team. The point is that you should always be communicating confidence, positivity, and an eagerness to find solutions--these are traits that people will admire regardless of the circumstances.
If they come up empty, you add "I'm just looking for a reasonable accommodation [using those words specifically is important] that would allow me to demonstrate as best I can the value I would bring to your company." If they're dismissive, that's when you might show the doctor's note/documentation that you're carrying with you just in case. And if they still refuse at that point--well, they're probably breaking the law. It's up to you what you're willing to go through to try to see it enforced--but if they won't follow this law, who knows what other employee protection laws they'll disregard? Nothing left to do at that point but carefully document the experience and try again.