test_hamming.zig:5:25: error: root struct of file 'hamming' has no member named 'DnaError'
^ This error happens when I run tests. It is in the test code not in the solution.
A similar bug is in the Collatz Conjecture one too
Either you’re the first person to try to solve this exercise or this bug isn’t actually a big 
I believe you’re supposed to define that error type yourself in your solution.
You are right! The description could be a little more clearer.
The problem description/instructions or the failed test output? The former pulls from a common repository used across all tracks. I believe the latter is built into the language.
That the problem solver is required to define the Error type used by the tests. This is not made clear by the description
Yeah. It could probably be better surfaced, but that’s the Exercism model. The practice exercises all expect you to run tests, read the output and use that to understand the details of what is needed.