50 lines
1.2 KiB
Rust
50 lines
1.2 KiB
Rust
// Customize the `dev` profile to wrap around on overflow.
|
|
// Check Cargo's documentation to find out the right syntax:
|
|
// https://doc.rust-lang.org/cargo/reference/profiles.html
|
|
//
|
|
// For reasons that we'll explain later, the customization needs to be done in the `Cargo.toml`
|
|
// at the root of the repository, not in the `Cargo.toml` of the exercise.
|
|
|
|
pub fn factorial(n: u32) -> u32 {
|
|
let mut result = 1;
|
|
for i in 1..=n {
|
|
result *= i;
|
|
}
|
|
result
|
|
}
|
|
|
|
#[cfg(test)]
|
|
mod tests {
|
|
use crate::factorial;
|
|
|
|
#[test]
|
|
fn twentieth() {
|
|
// 20! is 2432902008176640000, which is too large to fit in a u32
|
|
// With the default dev profile, this will panic when you run `cargo test`
|
|
// We want it to wrap around instead
|
|
assert_eq!(factorial(20), 2_192_834_560);
|
|
// ☝️
|
|
// A large number literal using underscores to improve readability!
|
|
}
|
|
|
|
#[test]
|
|
fn first() {
|
|
assert_eq!(factorial(0), 1);
|
|
}
|
|
|
|
#[test]
|
|
fn second() {
|
|
assert_eq!(factorial(1), 1);
|
|
}
|
|
|
|
#[test]
|
|
fn third() {
|
|
assert_eq!(factorial(2), 2);
|
|
}
|
|
|
|
#[test]
|
|
fn fifth() {
|
|
assert_eq!(factorial(5), 120);
|
|
}
|
|
}
|