Validate a signup form in Rust
Rust interview exercise on Practical, difficulty 2 of 3. Solve it in the editor beside a worked example, or cold in Interview mode with the example hidden; the tests run the moment you do.
Write validate_signup(name, email, age) that collects every problem instead of stopping at the first. Return Ok(()) when valid, otherwise Err with the messages in this order: "name is required" (blank name), "email is invalid" (use the given is_email), "must be at least 13".
Each exercise pairs a worked example with a twin problem to solve in a real editor; the tests run the moment you do. Interview mode hides the example: solve it from memory, without the hint or the solution, and it counts as solved cold. Progress is saved in your browser, and in your account if you sign in.