Cloud Functions boilerplate with Node6 + Babel + ESLint + Prettier + AVA

.babelrc

{
  "presets": [
    [
      "@babel/preset-env",
      {
        "targets": {
          "node": "6.11.5"
        }
      }
    ]
  ]
}

.eslintrc.yaml

# Required for certain syntax usages
parserOptions: 
  ecmaVersion: 6
# for babel
parser: "babel-eslint"
plugins: 
  - promise
extends:
  - "eslint:recommended"
  - "plugin:prettier/recommended"
rules:
  # Removed rule "disallow the use of console" from recommended eslint rules
  no-console: off
  # Removed rule "disallow multiple spaces in regular expressions" from recommended eslint rules
  no-regex-spaces: off
  # Removed rule "disallow the use of debugger" from recommended eslint rules
  no-debugger: off
  # Removed rule "disallow unused variables" from recommended eslint rules
  no-unused-vars: off
  # Removed rule "disallow mixed spaces and tabs for indentation" from recommended eslint rules
  no-mixed-spaces-and-tabs: off
  # Removed rule "disallow the use of undeclared variables unless mentioned in /*global */ comments" from recommended eslint rules
  no-undef: off
  # Warn against template literal placeholder syntax in regular strings
  no-template-curly-in-string: warn
  # Warn if return statements do not either always or never specify values
  consistent-return: warn
  # Warn if no return statements in callbacks of array methods
  array-callback-return: warn
  # Require the use of === and !==
  eqeqeq: error
  # Disallow the use of alert, confirm, and prompt
  no-alert: error
  # Disallow the use of arguments.caller or arguments.callee
  no-caller: error
  # Disallow null comparisons without type-checking operators
  no-eq-null: error
  # Disallow the use of eval()
  no-eval: error
  # Warn against extending native types
  no-extend-native: warn
  # Warn against unnecessary calls to .bind()
  no-extra-bind: warn
  # Warn against unnecessary labels    
  no-extra-label: warn
  # Disallow leading or trailing decimal points in numeric literals
  no-floating-decimal: error
  # Warn against shorthand type conversions
  no-implicit-coercion: warn
  # Warn against function declarations and expressions inside loop statements
  no-loop-func: warn
  # Disallow new operators with the Function object
  no-new-func: error
  # Warn against new operators with the String, Number, and Boolean objects
  no-new-wrappers: warn
  # Disallow throwing literals as exceptions
  no-throw-literal: error
  # Require using Error objects as Promise rejection reasons
  prefer-promise-reject-errors: error
  # Enforce “for” loop update clause moving the counter in the right direction
  for-direction: error
  # Enforce return statements in getters
  getter-return: error
  # Disallow await inside of loops
  no-await-in-loop: off
  # Disallow comparing against -0
  no-compare-neg-zero: error
  # Warn against catch clause parameters from shadowing variables in the outer scope
  no-catch-shadow: warn
  # Disallow identifiers from shadowing restricted names
  no-shadow-restricted-names: error
  # Enforce return statements in callbacks of array methods
  callback-return: error
  # Require error handling in callbacks
  handle-callback-err: error
  # Warn against string concatenation with __dirname and __filename
  no-path-concat: warn
  # Prefer using arrow functions for callbacks
  prefer-arrow-callback: warn
  # Return inside each then() to create readable and reusable Promise chains.
  # Forces developers to return console logs and http calls in promises. 
  promise/always-return: error
  # Enforces the use of catch() on un-returned promises
  promise/catch-or-return: error
  # Warn against nested then() or catch() statements
  promise/no-nesting: warn
  prettier/prettier: 
    - error
    - trailingComma: es5