On: Cognitive load is what matters

[jreback]

Re: trust issues...I'd argue this is the purpose of automated tests. I think tests are too often left out of architectural discussions as if they are some additional artifact that gets created separately from the running software. The core / foundational / heavily reused parts of the architecture should have the most tests and ensure the consumers of those parts has no trust issues!

[K0nserv → jreback]

Tests are good but moving left by lifting invariants into the type system is better.

Compare

   fn send_email(addr: &str, subject: &str, body: &str) -> Result<()>

to

    fn send_email(add: &EmailAddr, subject: &str, body: &str) -> Result<()>

In the second case, the edge cases of an empty or invalid email address don't need to be tested, they are statically impossible.

[galangalalgol → K0nserv]

Thanks for the small concrete example. I try to explain this a lot. It also makes coverage really easy to get with fewer tests.