Respect ruby.pathToBundler for RuboCop executable

[spilist]

TL;DR: src/format/RuboCop.ts should use ruby.pathToBundler configuration when specified.

Since I'm new to vscode extension development, I didn't understand how to add / run tests for vscode extensions. Thanks in advance if anyone helps to improve this PR.

---

Environment

• vscode-ruby version: 0.20.0
• Ruby version: default 2.4.3, workspace 2.5.1
• Ruby version manager (if any): rvm
• VS Code version: 1.29.1
• Operating System: MacOS High Sierra (10.13.6)
• Using language server? no

Expected behavior

Use bundler to run AutoCorrect.test() by RubyDocumentFormattingEditProvider from ruby.pathToBundler when ruby.useBundler is true and ruby.pathToBundler is specified.

Actual behavior

It uses bundle from the default path.

Steps to find the problem

I'm using rvm for ruby version control, and my default version and worksapce version is different.

$ rvm ls
 * ruby-2.4.3 [ x86_64 ]
=> ruby-2.5.1 [ x86_64 ]

After installed rubocop, I configured my settings as following, to enable lint and auto formatting:

"ruby.format": "rubocop",
  "ruby.intellisense": "rubyLocate",
  "ruby.lint": {
    "rubocop": true
  },
  "[ruby]": {
    "editor.formatOnSave": true
  },
  "editor.formatOnSaveTimeout": 5000

But both lint and formatting didn't work. It said rubocop failed with code=7 which I couldn't understand.

After a few searchs, I added custom rubocop path in workspace settings and the lint started working.

"ruby.lint": {
    "rubocop": {
      "path": "/Users/ted/.rvm/gems/ruby-2.5.1/wrappers"
    }
  },

However, auto formatting never worked, and I found these messages from developer console.

[Extension Host] rubocop stderr /Users/ted/.rvm/gems/ruby-2.4.3/gems/bundler-1.17.1/lib/bundler/definition.rb:495:in `validate_ruby!': Your Ruby version is 2.4.3, but your Gemfile specified 2.5.1 (Bundler::RubyVersionMismatch)
	from /Users/ted/.rvm/gems/ruby-2.4.3/gems/bundler-1.17.1/lib/bundler/definition.rb:470:in `validate_runtime!'
	from /Users/ted/.rvm/gems/ruby-2.4.3/gems/bundler-1.17.1/lib/bundler.rb:101:in `setup'
	from /Users/ted/.rvm/gems/ruby-2.4.3/gems/bundler-1.17.1/lib/bundler/setup.rb:20:in `<top (required)>'
	from /Users/ted/.rvm/rubies/ruby-2.4.3/lib/ruby/site_ruby/2.4.0/rubygems/core_ext/kernel_require.rb:59:in `require'
	from /Users/ted/.rvm/rubies/ruby-2.4.3/lib/ruby/site_ruby/2.4.0/rubygems/core_ext/kernel_require.rb:59:in `require'

notificationsAlerts.ts:40 rubocop failed with code=1

So I added another configuration to specify bundler path. but no luck.

"ruby.useBundler": true,
"ruby.pathToBundler": "/Users/ted/.rvm/gems/ruby-2.5.1/wrappers/bundle"

I finally looked through the source code, and realized that although src/format/RuboCop.ts sees the ruby.useBundler option, it doesn't utilize ruby.pathToBundler to execute bundle. (24cb72f)

	// What's the exe name for rubocop?
	get exe(): string[] {
		const opts:any = this.opts;
		if (opts.exe) {
			return [opts.exe];
		}

		const ext: string = process.platform === 'win32' ? '.bat' : '';
		if (vscode.workspace.getConfiguration('ruby').useBundler) {
			return [`bundle${ext}`, 'exec', 'rubocop'];
		}

		return [`rubocop${ext}`];
	}

[wingrunr21]

Thank you for your contribution. I am aiming to merge this and cut a new release this weekend.

[spilist]

Fixed up the commit to use typescript syntax.