Why tests are so important for us
Unit tests are super handy for us. With a unit test, you can test a function and look if it behaves the way you want.
A good coder makes a mistake in 1 of 10 functions. A excellent coder makes a mistake in 1 of 30 functions. A visual impaired coder maybe makes a mistake in 1 of 3 functions.
But whatever your skill level may be, you make mistakes. Their are functions that do not behave as you wish they did. Good coders compensate their mistakes with unit tests. Because good coders do not make so many mistakes as we do, they do not depend on tests so much as we do so a lot of people skip them.
Here is where we as visual impaired coders can turn their disadvantage (introducing more bugs) in to a advantage. We need our tests in order to work. We introduce by accident possible bugs that we can later filter out with tests. This is why I write better code. I just write a test for every function and this way I get close to 100% test coverage.
Yes, we write code with more bugs, but we can compensate that with more tests and that way we build in the end more robust software then a visual coder who is too lazy to write tests.
Do not forget your tests. Almost every language has a system for writing unit tests, so learn how to use it.