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https://github.com/alexilyaev/jest-spy-object
Spies on all Object or Class methods using `jest.spyOn`
https://github.com/alexilyaev/jest-spy-object
Last synced: 2 days ago
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Spies on all Object or Class methods using `jest.spyOn`
- Host: GitHub
- URL: https://github.com/alexilyaev/jest-spy-object
- Owner: alexilyaev
- License: mit
- Created: 2018-02-19T17:16:30.000Z (over 6 years ago)
- Default Branch: master
- Last Pushed: 2018-12-31T20:19:11.000Z (almost 6 years ago)
- Last Synced: 2024-10-04T17:34:37.087Z (about 1 month ago)
- Language: JavaScript
- Size: 96.7 KB
- Stars: 6
- Watchers: 2
- Forks: 1
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- Contributing: CONTRIBUTING.md
- License: LICENSE
- Code of conduct: CODE_OF_CONDUCT.md
Awesome Lists containing this project
README
# jest-spy-object
[](https://circleci.com/gh/alexilyaev/jest-spy-object)
[](http://npm.im/jest-spy-object)
[](http://opensource.org/licenses/MIT)
[](http://makeapullrequest.com)
[](https://github.com/prettier/prettier)
Spies on all Object or Class methods using `jest.spyOn`.
## Why?
If you're sick of writing `jest.spyOn(Object, 'method')` all the time.
And you want the following:
* You need to spy on some or all methods of an Object or Class
* You need to define mocks for some methods inside tests (`mockImplementation` or `mockReturnValue`)
* You need each test to have fresh spies without calling `mockRretore` or `mockReset` on each spy
* You don't want to manually add a spy for newly added methods
## Installation
Install as a dev dependency of your project:
```
yarn add -D jest-spy-object
```
Or with `npm`
```
npm i -D jest-spy-object
```
## Require
```js
const spyObject = require('jest-spy-object');
```
## Usage
### Given a Class
```js
class Counter {
constructor() {
this.value = 0;
}
incrementBy(val) {
this.value = this.value + val;
}
increment() {
this.incrementBy(1);
}
}
```
### Before
```js
beforeEach(() => {
// Make sure each test starts fresh (can be set in jest.config.js with `restoreMocks: true`)
jest.restoreAllMocks();
// Setup fresh spies
jest.spyOn(Counter.prototype, 'incrementBy');
jest.spyOn(Counter.prototype, 'increment');
});
```
### After
```js
const spyObject = require('jest-spy-object');
beforeEach(() => {
// Make sure each test starts fresh (can be set in jest.config.js with `restoreMocks: true`)
jest.restoreAllMocks();
// Setup fresh spies
spyObject(Counter);
});
```
### Tests
```js
describe('Counter', () => {
it('should be able to spy on class methods and mock any of them easily', () => {
const counter = new Counter();
counter.incrementBy.mockImplementation(function() {
this.value = this.value + 10;
});
counter.increment();
expect(counter.increment).toHaveBeenCalled();
expect(counter.incrementBy).toHaveBeenCalledWith(1);
expect(counter.value).toBe(10);
});
});
```
## Other supported inputs
### Function constructor
```js
function Counter() {
this.value = 0;
}
Counter.prototype.incrementBy = function incrementBy(val) {
this.value = this.value + val;
};
Counter.prototype.increment = function increment() {
this.incrementBy(1);
};
spyObject(Counter);
// or...
spyObject(Counter.prototype);
```
### Plain Object
```js
const counter = {
value: 0,
incrementBy(val) {
this.value = this.value + val;
},
increment() {
this.incrementBy(1);
}
};
spyObject(counter);
```
## Contributing
See the [CONTRIBUTING](CONTRIBUTING.md) document.