"Cannot convert undefined or null to object" at installQuasar

Application uses vue3 + ts + quasar and jest for testing. Getting error “Cannot convert undefined or null to object” at installQuasar when doing localVue.use(Quasar) or plugins: [Quasar] in test file. The config files are as mentioned below

package.json -

"dependencies": {
    "@quasar/extras": "^1.11.4",
    "@types/vue-i18n": "^7.0.0",
    "axios": "^0.20.0",
    "core-js": "^3.6.5",
    "d3": "^6.2.0",
    "echarts": "^5.1.2",
    "lodash": "~4.17.20",
    "qs": "^6.9.6",
    "quasar": "^2.2.1",
    "rison": "^0.1.1",
    "vue": "3.0.6",
    "vue-i18n": "^9.1.5",
    "vue-router": "^4.0.12"
  },
  "devDependencies": {
    "@types/d3": "^5.16.3",
    "@types/echarts": "^4.9.8",
    "@types/lodash": "^4.14.160",
    "@types/node": "^14.17.32",
    "@types/rison": "0.0.6",
    "@types/webpack-env": "^1.16.3",
    "@typescript-eslint/eslint-plugin": "^5.3.1",
    "@typescript-eslint/parser": "^5.3.1",
    "@vue/cli-plugin-babel": "^4.5.14",
    "@vue/cli-plugin-eslint": "^4.5.14",
    "@vue/cli-plugin-router": "^4.5.14",
    "@vue/cli-plugin-typescript": "^4.5.14",
    "@vue/cli-plugin-unit-jest": "^4.5.15",
    "@vue/cli-service": "~4.5.0",
    "@vue/compiler-sfc": "3.0.0",
    "@vue/eslint-config-prettier": "^6.0.0",
    "@vue/eslint-config-typescript": "^9.0.1",
    "@vue/test-utils": "^2.0.0-0",
    "babel-core": "^7.0.0-bridge.0",
    "babel-plugin-transform-imports": "2.0.0",
    "eslint": "^7.0.0",
    "eslint-plugin-prettier": "^3.1.3",
    "eslint-plugin-vue": "^7.0.0",
    "node-sass": "4.13.0",
    "prettier": "^1.19.1",
    "sass-loader": "^8.0.2",
    "typescript": "~3.9.3",
    "vue-cli-plugin-quasar": "~4.0.4",
    "vue-jest": "^5.0.0-0"
  }

jest.config.js -

module.exports = {
  preset: "@vue/cli-plugin-unit-jest/presets/typescript-and-babel",
  transformIgnorePatterns: ["node_modules/(?!(quasar|echarts|zrender)/)"],
  transform: {
    // process *.vue files with vue-jest
    '^.+\\.vue$': require.resolve('vue-jest'),
  }
};

babel.config.js -

module.exports = {
  presets: ["@vue/cli-plugin-babel/preset"]
};

test file assets.spec.ts-

import { Quasar } from "quasar";
import { createApp } from "vue";

const localVue = createApp({});
localVue.use(Quasar);

Error

 Test suite failed to run

    TypeError: Cannot convert undefined or null to object
        at Function.assign (<anonymous>)

      4 |
      5 | const localVue = createApp({});
    > 6 | localVue.use(Quasar);
        |          ^
      7 |

      at installQuasar (node_modules/quasar/dist/quasar.cjs.prod.js:6:13539)
      at Object.install (node_modules/quasar/dist/quasar.cjs.prod.js:6:468377)
      at Object.use (node_modules/@vue/runtime-core/dist/runtime-core.cjs.js:2962:28)
      at Object.<anonymous> (tests/unit/assets.spec.ts:6:10)

[yusufkandemir]

Here is a solution that is based on a Vite setup: https://github.com/quasarframework/quasar/discussions/12177#discussioncomment-2046577.

I am hoping to create an example repo and write a tutorial/article about Vue CLI and Vite setups.

[IlCallo]

Correct, CJS exported version is optimized for SSR, so it will give you all kind of weird issues while testing You need to add these lines to your jest config to use and transform the ESM build version:

• https://github.com/quasarframework/quasar-testing/blob/5a761b2d8f25656d09d237a525e96cf60e5401ae/packages/unit-jest/src/templates/typescript/jest.config.js#L1
• https://github.com/quasarframework/quasar-testing/blob/5a761b2d8f25656d09d237a525e96cf60e5401ae/packages/unit-jest/src/templates/typescript/jest.config.js#L56
• https://github.com/quasarframework/quasar-testing/blob/5a761b2d8f25656d09d237a525e96cf60e5401ae/packages/unit-jest/src/templates/typescript/jest.config.js#L79

Also take a look to https://github.com/quasarframework/quasar-testing/blob/5a761b2d8f25656d09d237a525e96cf60e5401ae/packages/unit-jest/src/helpers/install-quasar-plugin.ts#L6 implementation and usage, as Yusuf correctly pointed out.