Setting up eslint and tests running before each commit.

before_commit_hook

##Setting up eslint and tests running before each commit.

 1. `npm install --save-dev husky`
 2. `npm install --save-dev lint-staged`
 4. Add husky config to run lint-staged script before every commit

```
  "husky": {
      "hooks": {
        "pre-commit": "lint-staged"
      }
    },
```

 5. Add lint staged config to run eslint and tests for modified files
 ```"lint-staged": {
    "linters": {
      "*.{js,scss}": [
        "eslint --fix",
        "npm run test:unit",
        "git add"
      ]
    }
},
```
 6. Add `test:unit` command in scripts section 
```
"test:unit": "jest --coverage", 
```

#After this you can modify your code and do your stuff. 
#This will notify you about problems with eslint in modified files and test cases.