在现代软件开发中，自动化测试是保证代码质量、减少人为错误和提高开发效率的关键实践之一。Rust 语言以其内存安全性和并发性能著称，逐渐成为系统级编程的重要工具。然而，许多开发者在 Rust 的自动化测试方面还缺乏全面的了解与实践经验。本指南将全面介绍 Rust 的自动化测试，从基础的单元测试到更复杂的集成测试和性能测试，帮助开发者掌握自动化测试的核心概念与技巧。无论你是 Rust 的新手，还是有一定经验的开发者，这篇文章都将为你提供切实可行的测试解决方案，助力你的项目开发与维护。
本文旨在全面介绍 Rust 的自动化测试，包括其基础概念、工具、最佳实践和进阶技巧。文章首先介绍了 Rust 的基本测试框架，包括如何编写和运行单元测试，随后深入探讨了如何进行集成测试、性能测试以及使用 Mock 和 Test Doubles 等技术。我们还将介绍一些 Rust 生态中的常用测试工具与库，例如 cargo test、mockall 和 criterion，并探讨如何构建高效、易维护的自动化测试套件。通过本指南，读者将能够充分利用 Rust 的测试工具，提升开发效率，确保代码质量，并轻松应对开发过程中的各种挑战。
测试：
测试函数体（通常）执行的 3 个操作：
测试函数需要使用 test 属性（attribute）进行标注
使用 cargo test 命令运行所有测试函数
当使用 cargo 创建 library 项目的时候，会生成一个 test module，里面有一个 test 函数
~/rust
➜ cargo new adder --lib
Created library `adder` package
~/rust
➜ cd adder
adder on master [?] via 🦀 1.67.1
➜ code .
adder on master [?] via 🦀 1.67.1 took 2.2s
➜
~/rust
➜ cargo new adder --lib
Created library `adder` package
~/rust
➜ cd adder
adder on master [?] via 🦀 1.67.1
➜ code .
adder on master [?] via 🦀 1.67.1 took 2.2s
➜
lib.rs 文件
pub fn add(left: usize, right: usize) -> usize {
left + right
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn it_works() {
let result = add(2, 2);
assert_eq!(result, 4);
}
}
pub fn add(left: usize, right: usize) -> usize {
left + right
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn exploration() {
let result = add(2, 2);
assert_eq!(result, 4);
}
#[test]
fn another() {
panic!("Make this test fail")
}
}
运行
adder on master [?] is 📦 0.1.0 via 🦀 1.67.1 took 3.0s
➜ cargo test
Compiling adder v0.1.0 (/Users/qiaopengjun/rust/adder)
Finished test [unoptimized + debuginfo] target(s) in 0.16s
Running unittests src/lib.rs (target/debug/deps/adder-6058f7b13179a51e)
running 2 tests
test tests::exploration ... ok
test tests::another ... FAILED
failures:
---- tests::another stdout ----
thread 'tests::another' panicked at 'Make this test fail', src/lib.rs:17:9
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
failures:
tests::another
test result: FAILED. 1 passed; 1 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
error: test failed, to rerun pass `--lib`
adder on master [?] is 📦 0.1.0 via 🦀 1.67.1
assert! 宏，来自标准库，用来确定某个状态是否为 true
#[derive(Debug)]
pub struct Rectangle {
length: u32,
width: u32,
}
impl Rectangle {
pub fn can_hold(&self, other: &Rectangle) -> bool {
self.length > other.length && self.width > other.width
}
}
#[cfg(test)]
mod tests {
use super::*
#[test]
fn larger_can_hold_smaller() {
let larger = Rectangle {
length: 8,
width: 7,
};
let smaller = Rectangle {
length: 5,
width: 1,
};
assert!(larger.can_hold(&smaller));
}
#[test]
fn samller_cannot_hold_larger() {
let larger = Rectangle {
length: 8,
width: 7,
};
let smaller = Rectangle {
length: 5,
width: 1,
};
assert!(!smaller.can_hold(&larger));
}
}
都来自标准库
判断两个参数是否相等或不等
实际上，它们使用的就是 == 和 !== 运算符
断言失败，自动打印出两个参数的值
pub fn add_two(a: i32) -> i32 {
a + 2
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn it_adds_two() {
// assert_eq!(4, add_two(2));
assert_ne!(5, add_two(2));
}
}
可以向 assert!、assert_eq!、assert_ne! 添加可选的自定义消息
pub fn greeting(name: &str) -> String {
//format!("Hello {}!", name)
format!("Hello!")
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn greetings_contain_name() {
let result = greeting("Carol");
// assert!(result.contains("Carol"));
assert!(
result.contains("Carol"),
"Greeting didn't contain name, value was '{}'", result
);
}
}
测试除了验证代码的返回值是否正确，还需验证代码是否如预期的处理了发生错误的情况
可验证代码在特定情况下是否发生了 panic
should_panic 属性（attribute）：
pub struct Guess {
value: u32,
}
impl Guess {
pub fn new(value: u32) -> Guess {
if value < 1 || value > 100 {
panic!("Guess value must be between 1 and 100, got {}.", value)
}
Guess {value}
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
#[should_panic]
fn greater_than_100() {
Guess::new(200);
}
}
为 should_panic 属性添加一个可选的 expected 参数：
pub struct Guess {
value: u32,
}
impl Guess {
pub fn new(value: u32) -> Guess {
if value < 1 {
panic!("Guess value must be greater than or equal to 1, got {}.", value)
} else if value > 100 {
panic!("Guess value must be less than or equal to 100, got {}.", value)
}
Guess {value}
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
#[should_panic(expected = "Guess value must be less than or equal to 100")]
fn greater_than_100() {
Guess::new(200);
}
}
无需 panic，可使用 Result 作为返回类型编写测试：
#[cfg(test)]
mod tests {
#[test]
fn it_works() -> Result<(), String> {
if 2 + 2 == 4 {
Ok(())
} else {
Err(String::from("two plus two does not equal four"))
}
}
}
改变 cargo test 的行为：添加命令行参数
默认行为：
命令行参数：
运行多个测试：默认使用多个线程并行运行
确保测试之间：
默认，如测试通过，Rust 的 test 库会捕获所有打印到标准输出的内容
例如，如果被测试代码中用到了 println!：
fn prints_and_returns_10(a: i32) -> i32 {
println!("I got the value {}", a);
10
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn this_test_will_pass() {
let value = prints_and_returns_10(4);
assert_eq!(10, value);
}
#[test]
fn this_test_will_fail() {
let value = prints_and_returns_10(8);
assert_eq!(5, value);
}
}
pub fn add_two(a: i32) -> i32 {
a + 2
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn add_two_and_two() {
assert_eq!(4, add_two(2));
}
#[test]
fn add_three_and_two() {
assert_eq!(5, add_two(3));
}
#[test]
fn one_hundred() {
assert_eq!(102, add_two(100));
}
}
cargo test one_hundred
cargo test add
#[cfg(test)]
mod tests {
#[test]
fn it_works() {
assert_eq!(4, 2 + 2);
}
#[test]
#[ignore]
fn expensive_test() {
assert_eq!(5, 1 + 1 + 1 + 1 + 1);
}
}
运行被忽略（ignore）的测试：
cargo test -- --ignored
Rust 对测试的分类：
单元测试：
集成测试：
单元测试
tests 模块上的 #[cfg(test)] 标注：
集成测试在不同的目录，它不需要 #[cfg(test)] 标注
cfg：configuration（配置）
配置选项 test：由 Rust 提供，用来编译和运行测试
#[cfg(test)]
mod tests {
#[test]
fn it_works() {
assert_eq!(4, 2 + 2);
}
}
pub fn add_two(a: i32) -> i32 {
internal_adder(a, 2)
}
fn internal_adder(a: i32, b: i32) -> i32 {
a + b
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn it_works() {
assert_eq!(4, internal_adder(2, 2));
}
}
创建集成测试：tests 目录
tests 目录下的每个测试文件都是单独的一个 crate
无需标注 #[cfg(test)]，tests 目录被特殊对待
src/lib.rs 文件
pub fn add(left: usize, right: usize) -> usize {
left + right
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn exploration() {
let result = add(2, 2);
assert_eq!(result, 4);
}
// #[test]
// fn another() {
// panic!("Make this test fail")
// }
}
tests/integration_test.rs 文件
use adder;
#[test]
fn it_add() {
assert_eq!(5, adder::add(2, 3));
}
运行
adder on master [?] is 📦 0.1.0 via 🦀 1.67.1
➜ cargo test
Compiling adder v0.1.0 (/Users/qiaopengjun/rust/adder)
Finished test [unoptimized + debuginfo] target(s) in 0.11s
Running unittests src/lib.rs (target/debug/deps/adder-6058f7b13179a51e)
running 1 test
test tests::exploration ... ok
test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
Running tests/integration_test.rs (target/debug/deps/integration_test-461b916f2718e782)
running 1 test
test it_add ... ok
test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
Doc-tests adder
running 0 tests
test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
adder on master [?] is 📦 0.1.0 via 🦀 1.67.1
tests/another_integration_tests.rs 文件
use adder;
#[test]
fn it_adds2() {
assert_eq!(7, adder::add(3,4));
}
运行
adder on master [?] is 📦 0.1.0 via 🦀 1.67.1
➜ cargo test --test integration_test
Finished test [unoptimized + debuginfo] target(s) in 0.00s
Running tests/integration_test.rs (target/debug/deps/integration_test-461b916f2718e782)
running 1 test
test it_add ... ok
test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
adder on master [?] is 📦 0.1.0 via 🦀 1.67.1
➜ cargo test --test another_integration_tests
Compiling adder v0.1.0 (/Users/qiaopengjun/rust/adder)
Finished test [unoptimized + debuginfo] target(s) in 0.11s
Running tests/another_integration_tests.rs (target/debug/deps/another_integration_tests-0a89cbf68d5b375f)
running 1 test
test it_adds2 ... ok
test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
adder on master [?] is 📦 0.1.0 via 🦀 1.67.1
tests 目录下每个文件被编译成单独的 crate
adder on master [?] is 📦 0.1.0 via 🦀 1.67.1
➜ tree
.
├── Cargo.lock
├── Cargo.toml
├── src
│ └── lib.rs
├── target
│ ├── CACHEDIR.TAG
│ ├── debug
│ └── tmp
└── tests
├── another_integration_tests.rs
├── common
│ └── mod.rs
└── integration_test.rs
27 directories, 205 files
tests/common/mod.rs 文件
pub fn setup() {}
tests/another_integration_tests.rs 文件
use adder;
mod common;
#[test]
fn it_adds2() {
common::setup();
assert_eq!(7, adder::add(3,4));
}
tests/integration_test.rs 文件
use adder;
mod common;
#[test]
fn it_add() {
common::setup();
assert_eq!(5, adder::add(2, 3));
}
如果项目是 binary Crate，只含有 src/main.rs 没有 src/lib.rs：
只有 library crate 才能暴露函数给其它 crate 用
binary crate 意味着独立运行
通过本文的学习，开发者不仅能够掌握 Rust 的自动化测试基础，还能进一步了解如何使用高级测试技术来解决实际开发中的复杂问题。自动化测试是提高软件质量的有效手段，而 Rust 的强类型系统和优秀的编译器使得测试变得更加高效和安全。希望这篇指南能帮助你构建一个健壮的自动化测试体系，让你在开发过程中更加得心应手。如果你有任何问题或想法，欢迎与我们讨论，继续深入 Rust 的测试领域。