.eslintrc.json

{
  // Prevent ESLint from looking for other configurations in parent directories
  "root": true,
  // Enable the use of global variables
  "env": {
      // From every ECMAScript release until ES2021
      "es2021": true,
      // From Node.js environment
      "node": true
  },
  // Extend existing configurations
  // Order matters, each extension overrides the previous one
  "extends": [
      // Airbnb base config uses import plugin
      "airbnb-base",
      // Airbnb typescript base config uses @typescript-eslint plugin and overrides airbnb base config
      "airbnb-typescript/base"
  ],
  "overrides": [
      {
          // Run testing rules only against test files
          "files": ["**/__tests__/**/*.[jt]s?(x)", "**/?(*.)+(spec|test).[jt]s?(x)"],
          "extends": ["plugin:jest/recommended"],
          "env": {
            "jest/globals": true
          },
          "rules": {
              // Allow nesting describe/test callbacks in Jest tests
              "max-nested-callbacks": "off",

              // Allow magic numbers in tests
              "no-magic-numbers": "off"
          }
      }
  ],
  "parser": "@typescript-eslint/parser",
  "parserOptions": {
      // Link the typescript parser to the local typescript configuration
      "project": "./tsconfig.json",
      // Enable the use of syntax from latest ECMAScript releases
      "ecmaVersion": "latest",
      // Enable the use of syntax from ECMAScript modules
      "sourceType": "module"
  },
  "ignorePatterns": ["swagger-static"],
  "rules": {
      // Force all functions have explicit return type
      "@typescript-eslint/explicit-function-return-type": ["error", { "allowExpressions": true }],

      // Enforce consistent use of double quotes instead of single quotes to define strings
      // IMHO having to escape single quotes is more annoying than escaping double quotes because
      // single quotes are mandatory for contractions though double quotes never are mandatory
      // See http://stackoverflow.com/a/18041188/1480391
      // https://typescript-eslint.io/rules/quotes/
      "quotes": "off",
      "@typescript-eslint/quotes": [
          "error",
          "double",
          {
              "avoidEscape": true
          }
      ],

      // Enforce a convention in module import order
      // https://github.com/benmosher/eslint-plugin-import/blob/master/docs/rules/order.md
      "import/order": [
          "error",
          {
              "newlines-between": "never",
              "groups": [
                  "builtin",
                  "external",
                  "internal",
                  "parent",
                  "sibling",
                  "index"
              ],
              "alphabetize": {
                  "order": "asc",
                  "caseInsensitive": false
              }
          }
      ],

      // Enforce the export default when there is a single export from a module
      // Disabled to follow Nest guidelines
      // https://github.com/import-js/eslint-plugin-import/blob/main/docs/rules/prefer-default-export.md
      "import/prefer-default-export": "off",

      // Enforce the maximum depth callbacks that can be nested
      // https://eslint.org/docs/latest/rules/max-nested-callbacks
      "max-nested-callbacks" : ["error", 4],

      // Disallow the use of console
      // Disabled because that's a good practice in frontend only
      // https://eslint.org/docs/latest/rules/no-console
      "no-console": "off",

      // Enforce the use of explicit constants instead of meaningless numbers
      // https://eslint.org/docs/rules/no-magic-numbers
      "no-magic-numbers": [
          "error",
          {
              "ignore": [
                  -1,
                  0,
                  1,
                  2,
                  3,
                  10,
                  100,
                  1000
              ],
              "ignoreArrayIndexes": true,
              "enforceConst": true,
              "detectObjects": false
          }
      ]
  }
}