How to test error conditions

Test error conditions by writing a test function that asserts the code panics when an error occurs. Use the #[should_panic] attribute on the test function to expect a panic, and call the code that triggers the error inside it.

#[cfg(test)]
mod tests {
    #[test]
    #[should_panic]
    fn test_error_condition() {
        // Code that triggers the error
        panic!("error occurred");
    }
}

Testing error conditions tells your test runner to expect your code to crash intentionally. It's like setting a trap to catch a specific bug; if the code doesn't crash when it should, the test fails. You use this to verify that your error handling triggers correctly under bad conditions.