unist-util-assert
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!Chatchat-badgechatunist utility to assert trees.
Contents
* [`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)
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 onlyesm. In Node.js (version 16+), install with npm:npm install unist-util-assert
In Deno with
esm.sh
esmsh:import {assert} from 'https://esm.sh/unist-util-assert@4'
In browsers with
esm.sh
esmsh:<script type="module">
import {assert} from 'https://esm.sh/unist-util-assert@4?bundle'
</script>
Use
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
Whentree
(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
Whentree
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
Whennode
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
Whennode
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
Wrappedfn
.AssertionError
Assertion error from node:assert
(TypeScript type).Type
type AssertionError = import('node:assert').AssertionError
Extensions
This module can be used as a base to test subsets of unist (for an example, seemdast-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 typeAssertionError
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
— assert mdast nodes
— assert hast nodes
— assert nlcst nodes
Contribute
Seecontributing.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 conductcoc. By interacting with this repository, organization, or community you agree to abide by its terms.