---
id: 587d824b367417b2b2512c47
title: Test if a Variable or Function is Defined
challengeType: 2
forumTopicId: 301602
---
## Description
As a reminder, this project is being built upon the following starter project on Repl.it, or cloned from GitHub.
## Instructions
Use assert.isDefined() or assert.isUndefined() to make the tests pass.
## Tests
```yml
tests:
- text: All tests should pass.
testString: getUserInput => $.get(getUserInput('url') + '/_api/get-tests?type=unit&n=1').then(data => {assert.equal(data.state,'passed'); }, xhr => { throw new Error(xhr.responseText); })
- text: You should choose the right assertion - isDefined vs. isUndefined.
testString: 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); })
- text: You should choose the right assertion - isDefined vs. isUndefined.
testString: 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); })
- text: You should choose the right assertion - isDefined vs. isUndefined.
testString: 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); })
```
## Challenge Seed
## Solution
```js
/**
Backend challenges don't need solutions,
because they would need to be tested against a full working project.
Please check our contributing guidelines to learn more.
*/
```