.eslintrc.yml

parser: babel-eslint
plugins:
  - flowtype
  - prettier
env:
  es6: true
  node: true
parserOptions:
  arrowFunctions: true
  binaryLiterals: true
  blockBindings: true
  classes: true
  defaultParams: true
  destructuring: true
  experimentalObjectRestSpread: true
  forOf: true
  generators: true
  globalReturn: true
  jsx: true
  modules: true
  objectLiteralComputedProperties: true
  objectLiteralDuplicateProperties: true
  objectLiteralShorthandMethods: true
  objectLiteralShorthandProperties: true
  octalLiterals: true
  regexUFlag: true
  regexYFlag: true
  restParams: true
  spread: true
  superInFunctions: true
  templateStrings: true
  unicodeCodePointEscapes: true

rules:
  # https://github.com/prettier/eslint-plugin-prettier#installation
  prettier/prettier: error

  # `eslint-plugin-flowtype` rule list based on `v2.50.0`
  # https://github.com/gajus/eslint-plugin-flowtype#eslint-plugin-flowtype

  flowtype/array-style-complex-type: [error, verbose]
  flowtype/array-style-simple-type: [error, verbose]
  flowtype/boolean-style: off
  flowtype/define-flow-type: error
  flowtype/delimiter-dangle: off
  flowtype/generic-spacing: off
  flowtype/newline-after-flow-annotation: [error, always]
  flowtype/no-dupe-keys: error
  flowtype/no-existential-type: off
  flowtype/no-flow-fix-me-comments: off
  flowtype/no-mutable-array: off
  flowtype/no-primitive-constructor-types: error
  flowtype/no-types-missing-file-annotation: error
  #flowtype/no-unused-expressions: undecided
  flowtype/no-weak-types: [error, {any: false}]
  flowtype/object-type-delimiter: off
  flowtype/require-exact-type: off
  flowtype/require-parameter-type: off
  flowtype/require-return-type: off
  flowtype/require-types-at-top: off
  flowtype/require-valid-file-annotation: [error, always, { annotationStyle: block }]
  flowtype/require-variable-type: off
  flowtype/semi: off
  flowtype/sort-keys: off
  flowtype/space-after-type-colon: off
  flowtype/space-before-generic-bracket: off
  flowtype/space-before-type-colon: off
  flowtype/type-id-match: off
  #flowtype/type-import-style: undecided
  flowtype/union-intersection-spacing: off
  flowtype/use-flow-type: error
  flowtype/valid-syntax: off

  ##################################################
  # ESLint builtin rules list based on `v5.6.0`
  ##################################################

  # Possible Errors
  # https://eslint.org/docs/rules/#possible-errors

  for-direction: error
  getter-return: error
  no-async-promise-executor: error
  no-await-in-loop: error
  no-compare-neg-zero: error
  no-cond-assign: error
  no-console: warn
  no-constant-condition: error
  no-control-regex: off
  no-debugger: warn
  no-dupe-args: error
  no-dupe-keys: error
  no-duplicate-case: error
  no-empty: error
  no-empty-character-class: error
  no-ex-assign: error
  no-extra-boolean-cast: error
  no-extra-parens: off
  no-extra-semi: off
  no-func-assign: error
  no-inner-declarations: [error, functions]
  no-invalid-regexp: error
  no-irregular-whitespace: error
  no-misleading-character-class: error
  no-obj-calls: error
  #no-prototype-builtins: undecided
  no-regex-spaces: error
  no-sparse-arrays: error
  no-template-curly-in-string: error
  no-unexpected-multiline: off
  no-unreachable: error
  no-unsafe-finally: error
  no-unsafe-negation: error
  require-atomic-updates: error
  use-isnan: error
  valid-jsdoc: off
  valid-typeof: error

  # Best Practices
  # https://eslint.org/docs/rules/#best-practices

  accessor-pairs: error
  array-callback-return: [error, { allowImplicit: true }]
  block-scoped-var: off
  class-methods-use-this: off
  complexity: off
  consistent-return: off
  curly: [error, all]
  default-case: off
  dot-location: off
  dot-notation: off
  eqeqeq: [error, smart]
  guard-for-in: error
  max-classes-per-file: off
  no-alert: error
  no-caller: error
  # TODO: recommended rule but disable due to errors in existing code
  # no-case-declarations: error
  no-div-regex: error
  no-else-return: error
  no-empty-function: off
  no-empty-pattern: error
  no-eq-null: off
  no-eval: error
  no-extend-native: error
  no-extra-bind: error
  no-extra-label: error
  no-fallthrough: error
  no-floating-decimal: off
  no-global-assign: error
  no-implicit-coercion: error
  no-implicit-globals: off
  no-implied-eval: error
  no-invalid-this: off
  no-iterator: error
  no-labels: [error, {allowLoop: true}]
  no-lone-blocks: error
  no-loop-func: off
  no-magic-numbers: off
  no-multi-spaces: off
  no-multi-str: error
  no-new: error
  no-new-func: off
  no-new-wrappers: error
  no-octal: error
  no-octal-escape: error
  no-param-reassign: error
  no-proto: error
  no-redeclare: error
  no-restricted-properties: off
  no-return-assign: error
  no-return-await: error
  no-script-url: error
  no-self-assign: error
  no-self-compare: off
  no-sequences: off
  no-throw-literal: error
  no-unmodified-loop-condition: error
  no-unused-expressions: error
  no-unused-labels: error
  no-useless-call: error
  no-useless-concat: error
  no-useless-escape: error
  no-useless-return: error
  no-void: error
  no-warning-comments: off
  no-with: error
  #prefer-promise-reject-errors: undecided
  radix: error
  #require-await: undecided
  require-unicode-regexp: off
  vars-on-top: off
  wrap-iife: off
  yoda: [error, never, {exceptRange: true}]

  # Strict Mode
  # https://eslint.org/docs/rules/#strict-mode

  strict: off

  # Variables
  # https://eslint.org/docs/rules/#variables

  init-declarations: off
  no-delete-var: error
  no-label-var: error
  no-restricted-globals: off
  no-shadow: error
  no-shadow-restricted-names: error
  no-undef: error
  no-undef-init: error
  no-undefined: off
  no-unused-vars: [error, {vars: all, args: after-used, argsIgnorePattern: "^_"}]
  no-use-before-define: off

  # Node.js and CommonJS
  # https://eslint.org/docs/rules/#nodejs-and-commonjs

  callback-return: error
  global-require: error
  handle-callback-err: [error, error]
  no-buffer-constructor: error
  no-mixed-requires: [error, true]
  no-new-require: error
  no-path-concat: error
  no-process-env: off
  no-process-exit: off
  no-restricted-modules: off
  no-sync: error

  # Stylistic Issues
  # https://eslint.org/docs/rules/#stylistic-issues

  array-bracket-newline: off
  array-bracket-spacing: off
  array-element-newline: off
  block-spacing: off
  brace-style: off
  camelcase: [error, {properties: always}]
  #capitalized-comments: undecided
  comma-dangle: off
  comma-spacing: off
  comma-style: off
  computed-property-spacing: off
  consistent-this: off
  eol-last: off
  func-call-spacing: off
  func-name-matching: off
  func-names: off
  func-style: off
  function-paren-newline: off
  id-blacklist: off
  id-length: off
  id-match: [error, "^(?:_?[a-zA-Z0-9]*)|[_A-Z0-9]+$"]
  implicit-arrow-linebreak: off
  indent: off
  jsx-quotes: off
  key-spacing: off
  keyword-spacing: off
  #line-comment-position: undecided
  linebreak-style: error
  lines-around-comment: off
  lines-between-class-members: off
  max-depth: off
  max-len: off
  max-lines: off
  max-lines-per-function: off
  max-nested-callbacks: off
  max-params: off
  max-statements: off
  max-statements-per-line: off
  #multiline-comment-style: undecided
  multiline-ternary: off
  new-cap: off
  new-parens: off
  newline-per-chained-call: off
  no-array-constructor: error
  no-bitwise: off
  no-continue: off
  no-inline-comments: off
  no-lonely-if: error
  no-mixed-operators: off
  no-mixed-spaces-and-tabs: off
  no-multi-assign: off
  no-multiple-empty-lines: off
  no-negated-condition: off
  no-nested-ternary: off
  no-new-object: error
  no-plusplus: off
  no-spaced-func: off
  no-restricted-syntax: off
  no-tabs: error
  no-ternary: off
  no-trailing-spaces: off
  no-underscore-dangle: off
  no-unneeded-ternary: error
  no-whitespace-before-property: off
  nonblock-statement-body-position: off
  object-curly-newline: off
  object-curly-spacing: off
  object-property-newline: off
  one-var: [error, never]
  one-var-declaration-per-line: off
  operator-assignment: [error, always]
  operator-linebreak: off
  padded-blocks: off
  padding-line-between-statements: off
  prefer-object-spread: error
  quote-props: off
  quotes: off
  #require-jsdoc: undecided
  semi: off
  semi-spacing: off
  semi-style: off
  sort-keys: off
  sort-vars: off
  space-before-blocks: off
  space-before-function-paren: off
  space-in-parens: off
  space-infix-ops: off
  space-unary-ops: off
  spaced-comment: [error, always]
  switch-colon-spacing: off
  template-tag-spacing: off
  unicode-bom: off
  wrap-regex: off

  # ECMAScript 6
  # https://eslint.org/docs/rules/#ecmascript-6

  arrow-body-style: off
  arrow-parens: off
  arrow-spacing: off
  constructor-super: error
  generator-star-spacing: off
  no-class-assign: error
  no-confusing-arrow: off
  no-const-assign: error
  no-dupe-class-members: error
  #no-duplicate-imports: undecided
  no-new-symbol: error
  no-restricted-imports: off
  no-this-before-super: error
  no-useless-computed-key: error
  no-useless-constructor: error
  no-useless-rename: error
  no-var: error
  object-shorthand: [error, always]
  prefer-arrow-callback: error
  prefer-const: error
  prefer-destructuring: off
  prefer-numeric-literals: error
  #prefer-rest-params: undecided
  prefer-spread: off
  prefer-template: off
  require-yield: off
  rest-spread-spacing: off
  #sort-imports: undecided
  #symbol-description: undecided
  template-curly-spacing: off
  yield-star-spacing: off

overrides:
  - files: "*"
    excludedFiles: "**/__tests__/**"
    rules:
      no-restricted-syntax:
        - error
        - selector: 'FunctionDeclaration[async=true]'
          message: >
            async functions are not allowed outside of the test suite because
            older versions of NodeJS do not support them without additional
            runtime dependencies. Instead, use explicit Promises.