eslint-plugin-roku

The ESLint custom plugin with rules and parser for .brs files.
Sample Project

ESLint plugin for BrightScript

We going to skip the part why linting is important so you can read more about it at ESLint site. Primary motivation for this development is absence of reliable tools for Roku development (at least at the time this work started) and performance criteria.

Latest tests gave measurement of about 14 seconds for a 1000 files of BrightScript
This plugin provides parsing and linting tool for your Roku project. While ESLint rules for Javascript are not 1 to 1 replaceable you are able to quickly develop or translate any other rules to work with brightscript. It's written in typescript but could use any JS- technology you like

VSCode Integration

"eslint.validate": [   {
    "language": "brightscript",
    "autoFix": false
} ],

Linter Warnings

Syntax Errors

Disable rules with comments

? "this is a valid log" ' eslint-disable-line

or

' eslint-disable-next-line [rule]
? "this is a valid log"

note: whole file eslint-disable does not work as there is no block quote in brightscript

Installation

You'll first need to install ESLint:
With Yarn

yarn add --dev eslint

With npm

$ npm i eslint --save-dev

Next, install eslint-plugin-roku:
With Yarn

yarn add --dev eslint-plugin-roku

With npm

$ npm install eslint-plugin-roku --save-dev

Note: If you installed ESLint globally (using the -g flag) then you must also install eslint-plugin-roku globally.

Configuration

{
  "extends": "plugin:roku/recommended",
  "rules": {
    "roku/no-print": "error",
    "roku/no-stop": "warn",
    "roku/sub-to-function": "warn",
    "roku/function-no-return": "warn",
    "roku/no-unused-params": "warn",
    "roku/function-no-return-type": "warn",
    "roku/function-name-camelcase": "warn",
    "roku/no-uninitialized-variables": "error",
    "roku/no-uninitialized-functions": "error",
  }
}

Plugin-Provided Rules

Just as any other project this one requires more feedback and linting rules ideas

Parsing and AST

This documentation will be available at https://github.com/RokuRoad/bright

Writing rules

https://eslint.org/docs/developer-guide/working-with-rules

Testing rules

Typical test for a rule will look like
Test runner and valid / invalid factories to wrap your test code into testable solution

import { invalidFactory, runTest, validFactory } from '../helpers'

Define name of your rule, it will be used to require it and run tests

const RULE_NAME = 'sub-to-function'

Provide prefix and suffix, so you can test function body or root element like library import of the function itself

const valid = validFactory(RULE_NAME, '', '')
const invalid = invalidFactory(RULE_NAME, '', '')

Define cases to match against. Invalid cases will provide error messages

runTest(RULE_NAME, {
  invalid: [
    [
      `sub a() as Dynamic
      end sub`,

      [ { message: 'Sub a should not have a return type (dynamic). Consider replacing it with Function' } ]
    ]
  ].map(invalid),
  valid: [
    `sub a()
      print a
     end sub
  `
  ].map(valid)
})

SceneGraph

Currently in development, check back soon. Rule will be aware of components tree structure so for instance if function is going to be overwritten or just mistakenly left empty.