How to test workability of large registration form?

I have the registration form on my site:

Now I'm testing(workability) the form and every time I make mistake in my code(wrong parameter name, dao problems) I have to retype all fields to test it one more time. Can I somehow automatize filling in? Are there something like plugins where I type field-value pairs and they will be filled for me?

What are best practices regarding my case?