Integration test
- Rust course
- Intermediate
- Lesson 85/115
- 4 min
Write integration tests with the tests/ folder.
Integration tests
Integration tests try the library like a user, only through the public (pub) API. They live in the tests/ folder at the project root, and each file is compiled as a separate crate:
istatistik/
├── Cargo.toml
├── src/lib.rs // pub fn ortalama(..)
└── tests/
└── hesaplar.rs
// tests/hesaplar.rs
use istatistik::ortalama;
#[test]
fn ortalama_dogru() {
assert_eq!(ortalama(&[2.0, 4.0]), 3.0);
}#[cfg(test)] isn't needed; the tests/ folder is compiled only during cargo test anyway.
Shared test helpers
Setup code used by several test files goes into tests/ortak/mod.rs; if it were tests/ortak.rs, it would count as a test file itself:
// tests/ortak/mod.rs
pub fn ornek_veri() -> Vec<f64> { vec![2.0, 4.0, 9.0] }
// tests/hesaplar.rs
mod ortak;
#[test]
fn uc_degerin_ortalamasi() {
let v = ortak::ornek_veri();
assert_eq!(istatistik::ortalama(&v), 5.0);
}Practice Test from outside
Imitate the library with mod istatistik and write pub fn ortalama(v: &[f64]) -> f64 in it. In main, check assert_eq!(istatistik::ortalama(&[2.0, 4.0]), 3.0) using only the public API, then print ortalama: 3.
Starter code
fn main() {
// buraya yaz
}Sample solution
mod istatistik {
pub fn ortalama(v: &[f64]) -> f64 {
v.iter().sum::<f64>() / v.len() as f64
}
}
fn main() {
let o = istatistik::ortalama(&[2.0, 4.0]);
assert_eq!(o, 3.0);
println!("ortalama: {}", o);
}Expected output
ortalama: 3
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 Can integration tests be written for a package with only <code>src/main.rs</code> (no library)?
- Yes, use main;
- Yes, automatically
- Only unit tests are needed
- Not directly; binary crates can't be imported, the logic must move to lib.rs Correct answer
Explanation: This is another reason for the habit of a thin main.rs with the logic in lib.rs.
2 Import the public API
// tests/hesaplar.rs
____ istatistik::ortalama;// tests/hesaplar.rs
use istatistik::ortalama;Explanation: Integration tests use the library from outside, by its crate name.
3 Test kind and location
| Term | Meaning |
|---|---|
Unit test |
mod tests inside src/ |
Integration test |
tests/*.rs |
Shared helper |
tests/ortak/mod.rs |
Doc test |
In /// comments |