testing - 如何在测试中模拟外部依赖项？

Question

这个问题在这里已经有了答案:





How can I test stdin and stdout?

(1 个回答)



Is there a cleaner way to test functions that use functions that require user input in Rust?

(1 个回答)



How can I test Rust methods that depend on environment variables?

(4 个回答)


3年前关闭。




我在实现中使用 extern crate 建模并实现了一辆汽车:

extern crate speed_control;

struct Car;

trait SpeedControl {
    fn increase(&self) -> Result<(), ()>;
    fn decrease(&self) -> Result<(), ()>;
}

impl SpeedControl for Car {
    fn increase(&self) -> Result<(), ()> {
        match speed_control::increase() {  // Here I use the dependency
          // ... 
        }
    }
    // ...
}

我想测试上面的实现，但在我的测试中我不想 speed_control::increase()表现得像在生产中一样 - 我想 mock 它。我怎样才能做到这一点？

Answer 1

我建议你包装后端函数 speed_control::increase在某些特征中:

trait SpeedControlBackend {
    fn increase();
}

struct RealSpeedControl;

impl SpeedControlBackend for RealSpeedControl {
    fn increase() {
        speed_control::increase();
    }
}

struct MockSpeedControl;

impl SpeedControlBackend for MockSpeedControl {
    fn increase() {
        println!("MockSpeedControl::increase called");
    }
}

trait SpeedControl {
    fn other_function(&self) -> Result<(), ()>;
}

struct Car<T: SpeedControlBackend> {
    sc: T,
}

impl<T: SpeedControlBackend> SpeedControl for Car<T> {
    fn other_function(&self) -> Result<(), ()> {
        match self.sc.increase() {
            () => (),
        }
    }
}