Deploy error on Heroku with /app/karma.config.js - node.js

Question

I got a React project with node.js, and want to deploy it on Heroku, I connect Heroku with my github repository: https://github.com/yeziyqf/SecureProgramConc
When the project building on Heroku, I got following error:
-----> Running Node.js buildpack tests...
essential-react#0.3.0 test /app
PHANTOMJS_BIN=./node_modules/.bin/phantomjs ./node_modules/karma/bin/karma start karma.config.js
07 03 2018 04:50:38.115:ERROR [config]: File /app/karma.config.js does not exist!
npm ERR! Test failed. See above for more details.
-----> Node.js buildpack tests failed with exit status 1
What is this problem? Locally I don't have this config file but my project works fine, anybody have a clue on it? Thanks!
Here is the package.json file:
{
"name": "essential-react",
"version": "0.3.0",
"description": "A minimal skeleton for building testable React apps using ES6.",
"main": "src/main.jsx",
"scripts": {
"postinstall": "npm run build",
"server": "node server.js",
"build": "webpack -p --config webpack.production.config.js",
"test": "PHANTOMJS_BIN=./node_modules/.bin/phantomjs ./node_modules/karma/bin/karma start karma.conf.js",
"test-cross-browser": "./node_modules/karma/bin/karma start karma.cross-browser.config.js",
"coveralls": "cat coverage/lcov.info | coveralls",
"clean": "rm build/app.js"
},
"repository": {
"type": "git",
"url": "https://github.com/pheuter/essential-react.git"
},
"keywords": [
"skeleton",
"template",
"react",
"quickstart"
],
"author": "Mark Fayngersh",
"license": "MIT",
"bugs": {
"url": "https://github.com/pheuter/essential-react/issues"
},
"homepage": "https://github.com/pheuter/essential-react",
"devDependencies": {
"coveralls": "^2.11.2",
"istanbul": "^0.3.7",
"istanbul-instrumenter-loader": "^0.1.2",
"karma": "^0.13.22",
"karma-coverage": "^0.2.7",
"karma-mocha": "^0.1.10",
"karma-phantomjs-launcher": "^0.1.4",
"karma-sauce-launcher": "^0.2.10",
"karma-sinon-chai": "^0.3.0",
"karma-webpack": "^1.5.0",
"phantomjs": "^1.9.16",
"react-hot-loader": "^1.2.3",
"react-scripts": "0.2.1",
"webpack-dev-server": "^1.7.0"
},
"dependencies": {
"autoprefixer": "^6.0.2",
"babel-core": "^5.4.7",
"babel-loader": "^5.1.3",
"bootstrap": "^3.3.5",
"bootstrap-social": "^4.9.1",
"bundle-loader": "^0.5.4",
"classnames": "^2.2.0",
"css-loader": "^0.28.9",
"express": "^4.12.3",
"extract-text-webpack-plugin": "^0.8.2",
"file-loader": "^0.8.4",
"firebase": "^4.10.0",
"font-awesome": "^4.4.0",
"history": "^1.13.0",
"jquery": "^2.1.4",
"lazy": "^1.0.11",
"less": "^2.5.3",
"less-loader": "^2.2.1",
"normalizr": "^1.1.0",
"nprogress": "^0.2.0",
"postcss-loader": "^0.6.0",
"postcss-nested": "^1.0.0",
"react": "^0.14.9",
"react-addons-css-transition-group": "^0.14.1",
"react-addons-transition-group": "^0.14.2",
"react-addons-update": "^15.3.0",
"react-bootstrap": "^0.27.0",
"react-dom": "^0.14.1",
"react-native-multiple-choice": "0.0.8",
"react-redux": "^5.0.7",
"react-router": "^1.0.0-rc2",
"react-router-redux": "^4.0.8",
"react-select": "^1.2.1",
"redux": "^3.7.2",
"resource-api-utils": "^1.0.0",
"style-loader": "^0.12.3",
"url-loader": "^0.5.6",
"webpack": "^1.12.1"
}
}