fix duplicate controllers in manifest on update

[nachiket87]

Fixes hotwired/stimulus#739

when typescript and js controllers are named the same. For example, hello_controller.js and hello_controller.ts and placed in the controllers folder, index.js is updated with duplicate content to register the controllers.

// This file is auto-generated by ./bin/rails stimulus:manifest:update
// Run that command whenever you add a new controller or create them with
// ./bin/rails generate stimulus controllerName

import { application } from "./application"

import HelloController from "./hello_controller"
application.register("hello", HelloController)

import HelloController from "./hello_controller"
application.register("hello", HelloController)

[nachiket87]

what do you think @adrienpoly ?

[jasonfb]

I understand now. the controllers are written in typescript, of course, and the extra .js file are an artifact of the tsc watch process. I see what the issue is.

[adrienpoly]

thanks @jasonfb for confirming the reproduction of this issue. I am not familiar with tsc process generating extra .js file but if you confirm this is you issue then it looks like this will fix it.

@nachiket87 could you add a test to cover this ?

[nachiket87]

Thanks for the review @adrienpoly. I've added the test here: c55a28b

The issue can be verified by removing the .uniq here: https://github.com/nachiket87/stimulus-rails/blob/c55a28b7bbdcf45a0443bf97d258a31920b1f8ab/lib/stimulus/manifest.rb#L9

[nachiket87]

this PR - #77 introduced the issue.

@dhh can this be merged please.