The metaphor is slightly off-the-mark. Testing a fancy new white cane would be like testing the accessibility tool itself. If you are developing that, then you definitely need an expert in such tools (probably a blind person).
However, developing the site is more akin to developing... a hallway? You can test whether blind people can navigate your hallway by closing your eyes and walking down it whilst using a cane. This is a bit easier- you just need to make sure there aren't obvious pitfalls and dangerous obstacles, maybe that there's braille on the doors etc.
Having an actual blind person helping you out in the second case is obviously preferable, but if you cannot, I think most blind people would appreciate you putting in the effort and at least trying to make it accessible, as opposed to the alternative of not caring at all. A lot of accessibility is standardized and there are guides to follow. It can sometimes be tricky, to be sure, but it's doable.
However, developing the site is more akin to developing... a hallway? You can test whether blind people can navigate your hallway by closing your eyes and walking down it whilst using a cane. This is a bit easier- you just need to make sure there aren't obvious pitfalls and dangerous obstacles, maybe that there's braille on the doors etc.
Having an actual blind person helping you out in the second case is obviously preferable, but if you cannot, I think most blind people would appreciate you putting in the effort and at least trying to make it accessible, as opposed to the alternative of not caring at all. A lot of accessibility is standardized and there are guides to follow. It can sometimes be tricky, to be sure, but it's doable.