https://github.com/boneskull/unexpected-eventemitter
EventEmitter assertions for Unexpected
https://github.com/boneskull/unexpected-eventemitter
assertion-library assertions ee eventemitter nodejs unexpected
Last synced: 5 months ago
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EventEmitter assertions for Unexpected
- Host: GitHub
- URL: https://github.com/boneskull/unexpected-eventemitter
- Owner: boneskull
- License: other
- Created: 2017-03-05T19:42:20.000Z (about 8 years ago)
- Default Branch: main
- Last Pushed: 2024-12-28T14:04:12.000Z (5 months ago)
- Last Synced: 2024-12-28T15:17:46.743Z (5 months ago)
- Topics: assertion-library, assertions, ee, eventemitter, nodejs, unexpected
- Language: JavaScript
- Homepage:
- Size: 867 KB
- Stars: 4
- Watchers: 2
- Forks: 2
- Open Issues: 13
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- License: LICENSE
Awesome Lists containing this project
README
# unexpected-eventemitter
> [EventEmitter](https://nodejs.org/api/events.html#events_class_eventemitter) assertions for [Unexpected](http://unexpected.js.org/)
## Installation
```shell
$ npm i unexpected unexpected-eventemitter --save-dev
```
- This package requires Node.js v14+ _or_ a browser supporting ES6.
- [unexpected](http://unexpected.js.org) v10+ is a _peer dependency_ of this package.
- In a browser, this module is exposed as `globalThis.unexpectedEventEmitter` or `window.unexpectedEventEmitter`.
## Example
```js
import unexpected from 'unexpected';
import unexpectedEventEmitter from 'unexpected-eventemitter';
import {EventEmitter} from 'node:events';
const expect = unexpected.clone().use(unexpectedEventEmitter);
const ee = new EventEmitter();
// "to emit from" with sync function
expect(
() => {
ee.emit('foo', {bar: 'baz'});
},
'to emit from',
ee,
'foo',
{
bar: 'baz',
}
); // ok
// "to emit from" with async function
expect(
async () => {
await somethingAsync();
ee.emit('foo', {bar: 'baz'});
},
'to emit from',
ee,
'foo',
{
bar: 'baz',
}
); // ok
// "to emit from" with Promise
expect(
somethingAsync().then(() => {
ee.emit('foo', {bar: 'baz'});
}),
'to emit from',
ee,
'foo',
{
bar: 'baz',
}
); // ok
// "not to emit from" with async function
expect(
async () => {
await somethingAsync();
ee.emit('foo', {bar: 'baz'});
},
'not to emit from',
ee,
'foo'
); // assertion failure!
// "to emit with error from"
const err = new Error('uh oh');
expect(
Promise.resolve().then(() => {
ee.emit('foo', {bar: 'baz'});
throw err;
}),
'to emit with error from',
ee,
'foo',
err
); // ok
```
## Assertions
### `to emit from`
` [not] to emit from `
- `` may be a Promise, async, or synchronous function
- `` may be a duck-typed Node.js [EventEmitter](https://nodejs.org/api/events.html#events_class_eventemitter)
- `` is the event name
- `` corresponds to _zero (0) or more_ values which may be emitted. Do not use an array unless you expect the value to be an array!
- An `EventEmitter` emitting _more_ values than expected _will not_ fail an assertion.
- Values are checked with ["to satisfy"](http://unexpected.js.org/assertions/any/to-satisfy/) for flexibility.
### `to emit with error from`
` to emit with error from `
- Use when the subject `` emits, but _also_ throws or rejects.
- A strict equality check is made against `Error`
- There is no converse of this assertion; you cannot use `[not]`.
## Contributing
Please use the [Conventional Commits](https://www.conventionalcommits.org) commit message format.
## Related Projects
- [unexpected-events](https://npm.im/unexpected-events): Provides an alternative syntax, with the ability to test multiple events at once
## License
:copyright: 2017 [Christopher Hiller](https://boneskull.com). Licensed Apache-2.0.