> ## Documentation Index
> Fetch the complete documentation index at: https://bun.ll1025.cn/llms.txt
> Use this file to discover all available pages before exploring further.

# 在 `bun test` 中模拟函数

使用 `bun:test` 中的 `mock` 函数创建模拟对象。

```ts test.ts icon="https://mintcdn.com/span-inc/82N53aP7NFbaCVSl/icons/typescript.svg?fit=max&auto=format&n=82N53aP7NFbaCVSl&q=85&s=787d39d6a7d96d7f9540dc74344eba23" theme={null}
import { test, expect, mock } from "bun:test";

const random = mock(() => Math.random());
```

***

模拟函数可以接受参数。

```ts test.ts icon="https://mintcdn.com/span-inc/82N53aP7NFbaCVSl/icons/typescript.svg?fit=max&auto=format&n=82N53aP7NFbaCVSl&q=85&s=787d39d6a7d96d7f9540dc74344eba23" theme={null}
import { test, expect, mock } from "bun:test";

const random = mock((multiplier: number) => multiplier * Math.random());
```

***

`mock()` 的结果是一个装饰了额外属性的新函数。

```ts test.ts icon="https://mintcdn.com/span-inc/82N53aP7NFbaCVSl/icons/typescript.svg?fit=max&auto=format&n=82N53aP7NFbaCVSl&q=85&s=787d39d6a7d96d7f9540dc74344eba23" theme={null}
import { mock } from "bun:test";

const random = mock((multiplier: number) => multiplier * Math.random());

random(2);
random(10);

random.mock.calls;
// [[ 2 ], [ 10 ]]

random.mock.results;
//  [
//    { type: "return", value: 0.6533907460954099 },
//    { type: "return", value: 0.6452713933037312 }
//  ]
```

***

使用这些属性编写 `expect` 断言，验证模拟对象的使用情况：被调用次数、调用参数以及返回值。

```ts test.ts icon="https://mintcdn.com/span-inc/82N53aP7NFbaCVSl/icons/typescript.svg?fit=max&auto=format&n=82N53aP7NFbaCVSl&q=85&s=787d39d6a7d96d7f9540dc74344eba23" theme={null}
import { test, expect, mock } from "bun:test";

const random = mock((multiplier: number) => multiplier * Math.random());

test("随机", async () => {
  const a = random(1);
  const b = random(2);
  const c = random(3);

  expect(random).toHaveBeenCalled();
  expect(random).toHaveBeenCalledTimes(3);
  expect(random.mock.calls).toEqual([[1], [2], [3]]);
  expect(random.mock.results[0]).toEqual({ type: "return", value: a });
});
```

***

参见 [模拟](/test/mocks)。