Ecosyste.ms: Awesome

An open API service indexing awesome lists of open source software.

Awesome Lists | Featured Topics | Projects

https://github.com/syntax-tree/unist-util-assert

utility to assert nodes
https://github.com/syntax-tree/unist-util-assert

assert check syntax-tree test unist unist-util util

Last synced: 3 days ago
JSON representation

utility to assert nodes

Awesome Lists containing this project

README 

        
# unist-util-assert



[![Build][build-badge]][build]

[![Coverage][coverage-badge]][coverage]

[![Downloads][downloads-badge]][downloads]

[![Size][size-badge]][size]

[![Sponsors][sponsors-badge]][collective]

[![Backers][backers-badge]][collective]

[![Chat][chat-badge]][chat]



[unist][] utility to assert trees.



## Contents



*   [What is this?](#what-is-this)

*   [When should I use this?](#when-should-i-use-this)

*   [Install](#install)

*   [Use](#use)

*   [API](#api)

    *   [`assert(tree[, parent])`](#asserttree-parent)

    *   [`parent(tree[, parent])`](#parenttree-parent)

    *   [`literal(node[, parent])`](#literalnode-parent)

    *   [`_void(node[, parent])`](#_voidnode-parent)

    *   [`wrap(fn)`](#wrapfn)

    *   [`AssertionError`](#assertionerror)

*   [Extensions](#extensions)

*   [Types](#types)

*   [Compatibility](#compatibility)

*   [Related](#related)

*   [Contribute](#contribute)

*   [License](#license)



## What is this?



This package is a tiny utility that helps you deal with nodes.



## When should I use this?



This utility is typically useful when you expect certain nodes in your APIs

and want to make sure they’re valid and as expected.



Different utilities, [`mdast-util-assert`][mdast-util-assert],

[`hast-util-assert`][hast-util-assert], and [`nlcst-test`][nlcst-test],

do the same but for mdast, hast, and nlcst nodes, respectively.



## Install



This package is [ESM only][esm].

In Node.js (version 16+), install with [npm][]:



```sh

npm install unist-util-assert

```



In Deno with [`esm.sh`][esmsh]:



```js

import {assert} from 'https://esm.sh/unist-util-assert@4'

```



In browsers with [`esm.sh`][esmsh]:



```html



  import {assert} from 'https://esm.sh/unist-util-assert@4?bundle'



```



## Use



```js

import {_void, assert, parent} from 'unist-util-assert'



assert({type: 'root', children: []})

assert({type: 'break'})

assert({type: 'element', properties: {}, children: []})

// All OK.



assert({children: []})

// AssertionError: node should have a type: `{ children: [] }`



parent({type: 'break'})

// AssertionError: parent should have `children`: `{ type: 'break' }`



assert({type: 'element', properties: function() {}})

// AssertionError: non-specced property `properties` should be JSON: `{ type: 'element', properties: [Function] }`



_void({type: 'text', value: 'Alpha'})

// AssertionError: void should not have `value`: `{ type: 'text', value: 'Alpha' }`



assert({type: 'paragraph', children: ['foo']})

// AssertionError: node should be an object: `'foo'` in `{ type: 'paragraph', children: [ 'foo' ] }`

```



## API



This package exports the identifiers [`_void`][void], [`assert`][assert],

[`literal`][literal], [`parent`][parent], and [`wrap`][wrap].

There is no default export.



### `assert(tree[, parent])`



Assert that `tree` is a valid unist [`Node`][node].



If `tree` is a parent, all children will be asserted too.



###### Parameters



*   `tree` (`unknown`)

    — thing to assert

*   `parent` ([`Parent`][parent-node], optional)

    — optional, valid parent



###### Returns



Nothing.



###### Throws



When `tree` (or its descendants) is not a node.



### `parent(tree[, parent])`



Assert that `tree` is a valid unist [`Parent`][parent-node].



All children will be asserted too.



###### Parameters



*   `tree` (`unknown`)

    — thing to assert

*   `parent` ([`Parent`][parent-node], optional)

    — optional, valid parent



###### Returns



Nothing.



###### Throws



When `tree` is not a parent or its descendants are not nodes.



### `literal(node[, parent])`



Assert that `node` is a valid unist [`Literal`][literal-node].



###### Parameters



*   `tree` (`unknown`)

    — thing to assert

*   `parent` ([`Parent`][parent-node], optional)

    — optional, valid parent



###### Returns



Nothing.



###### Throws



When `node` is not a literal.



### `_void(node[, parent])`



Assert that `node` is a valid void node.



###### Parameters



*   `tree` (`unknown`)

    — thing to assert

*   `parent` ([`Parent`][parent-node], optional)

    — optional, valid parent



###### Returns



Nothing.



###### Throws



When `node` is not a node, a parent, or a literal.



### `wrap(fn)`



Wrapper that adds the current node (and parent, if available) to error

messages.



###### Parameters



*   `fn` (`(node?: any, parent?: Parent | null | undefined) => asserts node is Node)`)

    — custom assertion



###### Returns



Wrapped `fn`.



### `AssertionError`



Assertion error from `node:assert` (TypeScript type).



###### Type



```ts

type AssertionError = import('node:assert').AssertionError

```



## Extensions



This module can be used as a base to test subsets of unist (for an example, see

[`mdast-util-assert`][mdast-util-assert]).

All functions that are exposed from such a module, and functions used internally

to test children, should be wrapped in `wrap`, which adds an inspectable string

of the respective node, and its parent when available, to the exposed error

message.



## Types



This package is fully typed with [TypeScript][].

It exports the additional type [`AssertionError`][assertionerror].



## Compatibility



Projects maintained by the unified collective are compatible with maintained

versions of Node.js.



When we cut a new major release, we drop support for unmaintained versions of

Node.

This means we try to keep the current release line, `unist-util-assert@^4`,

compatible with Node.js 16.



## Related



*   [`mdast-util-assert`][mdast-util-assert]

    — assert mdast nodes

*   [`hast-util-assert`](https://github.com/syntax-tree/hast-util-assert)

    — assert hast nodes

*   [`nlcst-test`](https://github.com/syntax-tree/nlcst-test)

    — assert nlcst nodes



## Contribute



See [`contributing.md`][contributing] in [`syntax-tree/.github`][health] for

ways to get started.

See [`support.md`][support] for ways to get help.



This project has a [code of conduct][coc].

By interacting with this repository, organization, or community you agree to

abide by its terms.



## License



[MIT][license] © [Titus Wormer][author]



[build-badge]: https://github.com/syntax-tree/unist-util-assert/workflows/main/badge.svg



[build]: https://github.com/syntax-tree/unist-util-assert/actions



[coverage-badge]: https://img.shields.io/codecov/c/github/syntax-tree/unist-util-assert.svg



[coverage]: https://codecov.io/github/syntax-tree/unist-util-assert



[downloads-badge]: https://img.shields.io/npm/dm/unist-util-assert.svg



[downloads]: https://www.npmjs.com/package/unist-util-assert



[size-badge]: https://img.shields.io/badge/dynamic/json?label=minzipped%20size&query=$.size.compressedSize&url=https://deno.bundlejs.com/?q=unist-util-assert



[size]: https://bundlejs.com/?q=unist-util-assert



[sponsors-badge]: https://opencollective.com/unified/sponsors/badge.svg



[backers-badge]: https://opencollective.com/unified/backers/badge.svg



[collective]: https://opencollective.com/unified



[chat-badge]: https://img.shields.io/badge/chat-discussions-success.svg



[chat]: https://github.com/syntax-tree/unist/discussions



[npm]: https://docs.npmjs.com/cli/install



[esm]: https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c



[esmsh]: https://esm.sh



[typescript]: https://www.typescriptlang.org



[license]: license



[author]: https://wooorm.com



[health]: https://github.com/syntax-tree/.github



[contributing]: https://github.com/syntax-tree/.github/blob/main/contributing.md



[support]: https://github.com/syntax-tree/.github/blob/main/support.md



[coc]: https://github.com/syntax-tree/.github/blob/main/code-of-conduct.md



[unist]: https://github.com/syntax-tree/unist



[node]: https://github.com/syntax-tree/unist#node



[parent-node]: https://github.com/syntax-tree/unist#parent



[literal-node]: https://github.com/syntax-tree/unist#literal



[mdast-util-assert]: https://github.com/syntax-tree/mdast-util-assert



[hast-util-assert]: https://github.com/syntax-tree/hast-util-assert



[nlcst-test]: https://github.com/syntax-tree/nlcst-test



[assert]: #asserttree-parent



[parent]: #parenttree-parent



[literal]: #literalnode-parent



[void]: #_voidnode-parent



[wrap]: #wrapfn



[assertionerror]: #assertionerror