jest-bluster
v2.0.0
Published
Test both promises and callbacks in one go
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Test both promises and callbacks in one go.
Rationale
If your function supports both promise-style and continuation-passing-style asynchronous calls, bluster
will cut your tests in half.
Take this function for example:
function getResource(name: string): Promise<Resource>;
function getResource(name: string, callback: (error: Error, resource: Resource) => void): void;
(TypeScript types and overloading for clarity.)
Developers can call this function promise-style and continuation-passing-style (also known as callback-style). Whichever they prefer and fits the rest of the project. Cool! But how would you go about testing this? bluster
lets you test both branches at the cost of one.
Installation
Install jest-bluster
using npm or Yarn and add it to your Jest configuration in package.json:
{
…
"jest": {
"setupFilesAfterEnv": ["jest-bluster"]
},
…
}
Usage
Wrap your function using bluster
:
test('get-resource', () => {
return expect(
bluster(getResource)('example.gz')
).resolves.toMatchSnapshot();
});
The test above will fail if:
- either
const promise = getResource('example.gz')
orgetResource('example.gz', callback)
produces an error, or const promise = getResource('example.gz')
andgetResource('example.gz', callback)
produce different values, or- the value produced by both branches does not match the snapshot.
A passing test assures the function behaves correctly both when used promise-style and when used continuation-passing-style.
License (X11/MIT)
Copyright (c) 2019, 2023 Pimm "de Chinchilla" Hogeling
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
The Software is provided "as is", without warranty of any kind, express or implied, including but not limited to the warranties of merchantability, fitness for a particular purpose and noninfringement. in no event shall the authors or copyright holders be liable for any claim, damages or other liability, whether in an action of contract, tort or otherwise, arising from, out of or in connection with the Software or the use or other dealings in the Software.