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https://github.com/doug-wade/idd
Injection of Dependencies through Destructuring
https://github.com/doug-wade/idd
Last synced: 17 days ago
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Injection of Dependencies through Destructuring
- Host: GitHub
- URL: https://github.com/doug-wade/idd
- Owner: doug-wade
- Created: 2016-07-06T04:40:23.000Z (over 8 years ago)
- Default Branch: master
- Last Pushed: 2020-05-01T03:21:05.000Z (over 4 years ago)
- Last Synced: 2024-11-01T09:34:23.055Z (2 months ago)
- Language: JavaScript
- Size: 87.9 KB
- Stars: 1
- Watchers: 3
- Forks: 0
- Open Issues: 6
-
Metadata Files:
- Readme: README.md
- Contributing: CONTRIBUTING.md
Awesome Lists containing this project
README
# idd   
A dependency injection system with destructuring. Combines a common pattern
of using a single destructuring argument to avoid confusing the order of
arguments to high-parity functions, possibly with many optional parameters.
## Getting Started
To install the dependency injection system, use `npm install`
```shell
npm install --save idd
```
Then, from other peer directories, you can require the files as properties
on the directory's default export
lib/config.js
```javascript
export default function () {
return {
language: 'ru-ru',
level: 'info'
};
};
```
lib/greeter.js
```javascript
export default ({config, Logger}) => {
const logger = new Logger();
return {
greet: () => {
if (config.language === 'en-us') {
logger.log('Hello World!');
} else if (config.language === 'ru-ru') {
logger.log('Привет, мир!');
} else {
logger.error('unsupported language ' + config.language);
}
}
};
};
```
lib/Logger.js
```javascript
import chalk from 'chalk';
export default () => class Logger {
constructor() {
this.level = process.env.LEVEL;
}
log(msg) {
if (this.level !== 'quiet') {
console.log(msg);
}
}
error(msg) {
if (this.level !== 'quiet' && this.level !== 'silent') {
chalk.red(msg);
}
}
};
```
index.js
```javascript
import path from 'path';
import idd from '../../../..';
const {greeter} = idd(path.join(__dirname, 'lib'));
greeter.greet();
```
Then the output would be 'Hello World!'. If you were to change config to be
instead
```javascript
export default function() {
language: 'ru-ru',
level: 'error'
}
```
Then the output would be 'Привет, мир!'.
## Testing
A good dependency injection system should make unit testing easy. To mock out
your dependencies, just provide an optional third option with the mocks
```javascript
import {sinon} from 'sinon';
import idd from 'idd';
import test from 'ava';
test('Greet was called', t => {
const greet = sinon.spy();
const config = { greeting: 'Hello World!'};
const {greeter} = idd('./lib', { config, greet });
greeter.greet();
t.true(greet.calledOnce);
});
```