npm script doesn't not launch karma test correctly - npm

Question

I'm using parcel to build my project on windows , and installed karma as my test runner. I hope when I changed my source code the parcel would rebuild the project and the karma would execute the test.so I add
"script": {
"dev-test": "parcel watch test/* --no-cache & karma start --auto-watch"
}
to my package.json.
The weird thing is when I run "npm run dev-test" , the parcel build the project but karma didn't excute any test, terminal shows "√ Built in 5.95s.", that's all I got.
I have to type the whole command "parcel watch test/* --no-cache & npx karma start --auto-watch" in my command line line(karma isn't installed globally so I have to add npx), it seems to be a workaround, but still have a bug("&" means parcel and karma runs simultaneously so karma would run the test several times when parcel is building project)
I don't want to type the whole command , I hope I can use npm script.
here's my package.json if it helps
{
"name": "custom-vue-component",
"version": "1.0.0",
"description": "",
"main": "index.js",
"scripts": {
"test": "parcel build test/* --no-cache --no-minify && karma start --single-run",
"dev-test": "parcel watch test/* --no-cache & karma start --auto-watch"
},
"repository": {
"type": "git",
},
"author": "me",
"license": "ISC",
"dependencies": {
"vue": "^2.6.11",
"vue-hot-reload-api": "^2.3.4"
},
"devDependencies": {
"#vue/component-compiler-utils": "^3.1.2",
"chai": "^4.2.0",
"chai-spies": "^1.0.0",
"karma": "^5.0.9",
"karma-chai": "^0.1.0",
"karma-chai-spies": "^0.1.4",
"karma-chrome-launcher": "^3.1.0",
"karma-mocha": "^2.0.1",
"karma-sinon-chai": "^2.0.2",
"mocha": "^7.2.0",
"parcel-bundler": "^1.12.4",
"sass": "^1.26.7",
"sinon": "^9.0.2",
"sinon-chai": "^3.5.0",
"vue-template-compiler": "^2.6.11"
},
"alias": {
"vue": "./node_modules/vue/dist/vue.common.js"
}
}
and karma.conf.js
module.exports = function(config) {
config.set({
basePath: "",
frameworks: ["mocha", "sinon-chai"],
client: {
chai: {
includeStack: true,
},
},
files: ["dist/**/*.test.js", "dist/**/*.test.css"],
exclude: [],
preprocessors: {},
reporters: ["progress"],
port: 9876,
colors: true,
logLevel: config.LOG_INFO,
autoWatch: true,
browsers: ["ChromeHeadless"],
singleRun: false,
concurrency: Infinity,
});
}

Answer 1

If you are Windows user, you maybe meet this problem.
You can solve it by run parcel watch test/* --no-cache & karma start separately:
Open a git bush window and run npx parcel watch test/* --no-cache
Open another git bush window and run npx karma start