nodemon - 'mocha' is not recognized as an internal or external command, operable program or batch file.

mocha 테스트를 했더니, 다음과 같이 오류가 발생합니다.

c:\temp> nodemon --exec npm test
[nodemon] 1.19.1
[nodemon] to restart at any time, enter `rs`
[nodemon] watching: *.*
[nodemon] starting `npm test`

> tests@1.0.0 test E:\nodejs\weather-app\node-tests
> mocha **/*.test.js

'mocha' is not recognized as an internal or external command, operable program or batch file.
npm ERR! Test failed.  See above for more details.
[nodemon] app crashed - waiting for file changes before starting...

c:\temp> npm i mocha --save-dev

c:\temp> npm install -g mocha --save-dev

{
  "name": "tests",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "mocha **/*.test.js",
    "test-watch": "nodemon --exec npm test"
  },
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "mocha": "^6.1.4"
  }
}

c:\temp> npm run test-watch

c:\temp> nodemon --exec python test.py