.eslintrc.json

{
  "root": true,
  "parser": "@typescript-eslint/parser",
  "parserOptions": {
    "ecmaVersion": 6,
    "sourceType": "module",
    "project": ["./tsconfig.json", "./test/tsconfig.json", "./website/tsconfig.json", "./exampleWidget/tsconfig.json"]
  },
  "plugins": [
    "@typescript-eslint",
    "unused-imports",
    "testing-library",
    "jest-dom"
  ],
  "rules": {
    "@typescript-eslint/no-unused-vars": "error",
    "@typescript-eslint/semi": [2, "never"],
    "@typescript-eslint/space-before-function-paren": [2, "always"],
    "@typescript-eslint/indent": [2, 2],
    "unused-imports/no-unused-imports": "error",
    "unused-imports/no-unused-vars": 0,
    "max-len": [2, 120],
    "quotes": [2, "single"],
    "curly": "warn",
    "eqeqeq": "warn",
    "no-throw-literal": "warn",
    "semi": "off"
  },
  "overrides": [
    {
      "files": ["*.ts", "*.tsx"],
      "rules": {
        // see https://stackoverflow.com/questions/55280555/typescript-eslint-eslint-plugin-error-route-is-defined-but-never-used-no-un
        "no-unused-vars": "off",
        "@typescript-eslint/no-unused-vars": "error",
        "no-undef": "off",
        // allow overloads
        "no-redeclare": "off"
      }
    },
    {
      "files": [
        "**/__tests__/**/*.[jt]s?(x)",
        "**/?(*.)+(spec|test).[jt]s?(x)"
      ],
      "extends": [
        "plugin:testing-library/react",
        "plugin:jest-dom/recommended"
      ],
      "rules": {
        "testing-library/no-container": 1,
        "testing-library/no-node-access": 1
      }
    }
  ]
}