freeCodeCamp/curriculum/challenges/chinese/06-quality-assurance/quality-assurance-and-testing-with-chai/test-if-a-variable-or-function-is-defined.md

---
id: 587d824b367417b2b2512c47
title: 测试变量或函数是否已定义
challengeType: 2
forumTopicId: 301602
---

# --description--

请注意，本项目在 [这个 Repl.it 项目](https://repl.it/github/freeCodeCamp/boilerplate-mochachai) 的基础上进行开发。你也可以从 [GitHub](https://repl.it/github/freeCodeCamp/boilerplate-mochachai) 上克隆。

# --instructions--

使用 `assert.isDefined()` 或 `assert.isUndefined()` 让测试通过。

# --hints--

不应有未通过的测试

```js
(getUserInput) =>
  $.get(getUserInput('url') + '/_api/get-tests?type=unit&n=1').then(
    (data) => {
      assert.equal(data.state, 'passed');
    },
    (xhr) => {
      throw new Error(xhr.responseText);
    }
  );
```

请选择正确的断言—idDefined 或 idUndefined

```js
(getUserInput) =>
  $.get(getUserInput('url') + '/_api/get-tests?type=unit&n=1').then(
    (data) => {
      assert.equal(
        data.assertions[0].method,
        'isDefined',
        'Null is not undefined'
      );
    },
    (xhr) => {
      throw new Error(xhr.responseText);
    }
  );
```

请选择正确的断言—idDefined 或 idUndefined

```js
(getUserInput) =>
  $.get(getUserInput('url') + '/_api/get-tests?type=unit&n=1').then(
    (data) => {
      assert.equal(
        data.assertions[1].method,
        'isUndefined',
        'Undefined is undefined'
      );
    },
    (xhr) => {
      throw new Error(xhr.responseText);
    }
  );
```

请选择正确的断言—idDefined 或 idUndefined

```js
(getUserInput) =>
  $.get(getUserInput('url') + '/_api/get-tests?type=unit&n=1').then(
    (data) => {
      assert.equal(
        data.assertions[2].method,
        'isDefined',
        'A string is not undefined'
      );
    },
    (xhr) => {
      throw new Error(xhr.responseText);
    }
  );
```

# --solutions--