Implement a basic switch in main to enable v4 preview

lib/main-v4.coffee

@@ -0,0 +1,42 @@
+{CompositeDisposable} = require 'event-kit'
+[Minimap, MinimapElement] = []
+
+module.exports =
+class V4Main
+  @includeInto: (base) ->
+    for k,v of @prototype
+      base::[k] = v
+
+  activateV4: ->
+    @editorsMinimaps = {}
+    @subscriptions = new CompositeDisposable
+    MinimapElement ?= require './minimap-element'
+
+    MinimapElement.registerViewProvider()
+
+  deactivate: ->
+    @subscriptions.dispose()
+    @editorsMinimaps = {}
+    @toggled = false
+
+  toggle: ->
+    if @toggled
+      @toggled = false
+      @subscriptions.dispose()
+    else
+      @toggled = true
+      @initSubscriptions()
+
+  minimapForEditor: (editor) -> @editorsMinimaps[editor.id]
+
+  initSubscriptions: ->
+    Minimap ?= require './minimap'
+
+    @subscriptions.add atom.workspace.observeTextEditors (textEditor) =>
+      minimap = new Minimap({textEditor})
+      @editorsMinimaps[textEditor.id] = minimap
+
+      editorElement = atom.views.getView(textEditor)
+      minimapElement = atom.views.getView(minimap)
+
+      minimapElement.attach()

lib/main.coffee

@@ -2,6 +2,7 @@
 
 ViewManagement = require './mixins/view-management'
 PluginManagement = require './mixins/plugin-management'
+V4Main = null
 
 [MinimapPluginGeneratorView, deprecate, semver] = []
 
@@ -80,6 +81,10 @@ class Main
       minimum: 0
       maximum: 1
       description: "The opacity used to render the line's text in the minimap."
+    v4Preview:
+      type: 'boolean'
+      default: false
+      description: "Require Atom restart. Plugins will be disabled."
 
   # Internal: The activation state of the minimap package.
   active: false
@@ -91,20 +96,31 @@ class Main
 
   # Activates the minimap package.
   activate: ->
-    @subscriptions.add atom.commands.add 'atom-workspace',
-      'minimap:toggle': => @toggle()
-      'minimap:generate-plugin': => @generatePlugin()
+    @v4Preview = atom.config.get('minimap.v4Preview')
+
+    if @v4Preview
+      @version = '4.0.0-preview'
+      V4Main = require './main-v4'
+
+      V4Main.includeInto(Main)
 
-    workspaceElement = atom.views.getView(atom.workspace)
+      @activateV4()
 
-    if atom.config.get('minimap.displayPluginsControls')
+    else
       @subscriptions.add atom.commands.add 'atom-workspace',
-        'minimap:open-quick-settings': ->
-          editor = atom.workspace.getActiveEditor()
-          @minimapForEditor(editor).openQuickSettings.mousedown()
+        'minimap:toggle': => @toggle()
+        'minimap:generate-plugin': => @generatePlugin()
+
+      workspaceElement = atom.views.getView(atom.workspace)
+
+      if atom.config.get('minimap.displayPluginsControls')
+        @subscriptions.add atom.commands.add 'atom-workspace',
+          'minimap:open-quick-settings': ->
+            editor = atom.workspace.getActiveEditor()
+            @minimapForEditor(editor).openQuickSettings.mousedown()
 
-    @subscriptions.add atom.config.observe 'minimap.displayMinimapOnLeft', (value) ->
-      workspaceElement.classList.toggle 'minimap-on-left', value
+      @subscriptions.add atom.config.observe 'minimap.displayMinimapOnLeft', (value) ->
+        workspaceElement.classList.toggle 'minimap-on-left', value
 
     @toggle() if atom.config.get 'minimap.autoToggle'
 

spec/minimap-v4-spec.coffee

@@ -0,0 +1,52 @@
+{TextEditor} = require 'atom'
+Minimap = require '../lib/minimap'
+
+describe 'Minimap package v4', ->
+  [workspaceElement, minimapPackage] = []
+
+  beforeEach ->
+    atom.config.set 'minimap.v4Preview', true
+
+    waitsFor -> atom.packages.activatePackage('minimap')
+
+    runs ->
+      minimapPackage = atom.packages.getLoadedPackage('minimap').mainModule
+
+  afterEach ->
+    minimapPackage.deactivate()
+
+  it 'returns a custom version instead of the one in package.json', ->
+    expect(minimapPackage.version).toEqual('4.0.0-preview')
+
+  it 'match semver expression in 4.x', ->
+    expect(minimapPackage.versionMatch('4.x')).toBeTruthy()
+
+  it 'registers the minimap views provider', ->
+    textEditor = new TextEditor({})
+    minimap = new Minimap({textEditor})
+    minimapElement = atom.views.getView(minimap)
+
+    expect(minimapElement).toExist()
+
+  describe 'when an editor is opened', ->
+    [editor, minimap, editorElement, minimapElement] = []
+
+    beforeEach ->
+      waitsFor ->
+        atom.workspace.open('sample.coffee')
+
+      runs ->
+        workspaceElement = atom.views.getView(atom.workspace)
+        jasmine.attachToDOM(workspaceElement)
+
+      waitsFor -> atom.workspace.getActiveTextEditor()
+
+      runs ->
+        editor = atom.workspace.getActiveTextEditor()
+        editorElement = atom.views.getView(editor)
+
+    it 'creates a minimap model for the editor', ->
+      expect(minimapPackage.minimapForEditor(editor)).toBeDefined()
+
+    it 'attaches a minimap element to the editor view', ->
+      expect(editorElement.shadowRoot.querySelector('atom-text-editor-minimap')).toExist()