Implement minimap model destruction

lib/minimap.coffee

@@ -27,6 +27,12 @@ class Minimap extends Model
       @emitter.emit('did-change-scroll-top', scrollTop)
     subs.add @textEditor.onDidChangeScrollLeft (scrollLeft) =>
       @emitter.emit('did-change-scroll-left', scrollLeft)
+    subs.add @textEditor.onDidDestroy => @destroy()
+
+  destroyed: ->
+    @subscriptions.dispose()
+    @textEditor = null
+    @emitter.emit 'did-destroy'
 
   onDidChange: (callback) -> @emitter.on 'did-change', callback
 
@@ -38,6 +44,9 @@ class Minimap extends Model
   onDidChangeScrollLeft: (callback) ->
     @emitter.on 'did-change-scroll-left', callback
 
+  onDidDestroy: (callback) ->
+    @emitter.on 'did-destroy', callback
+
   getTextEditor: -> @textEditor
 
   getTextEditorHeight: -> @textEditor.getHeight() * @getVerticalScaleFactor()

spec/minimap-spec.coffee

@@ -2,7 +2,7 @@ fs = require 'fs-plus'
 {TextEditor} = require 'atom'
 Minimap = require '../lib/minimap'
 
-describe 'Minimap', ->
+fdescribe 'Minimap', ->
   [editor, minimap, largeSample, smallSample] = []
 
   beforeEach ->
@@ -22,6 +22,9 @@ describe 'Minimap', ->
   it 'has an associated editor', ->
     expect(minimap.getTextEditor()).toEqual(editor)
 
+  it 'returns false when asked if destroyed', ->
+    expect(minimap.isDestroyed()).toBeFalsy()
+
   it 'raise an exception if created without a text editor', ->
     expect(-> new Minimap).toThrow()
 
@@ -143,6 +146,27 @@ describe 'Minimap', ->
       it 'computes the last visible row in the minimap', ->
         expect(minimap.getLastVisibleScreenRow()).toEqual(largeLineCount)
 
+  describe 'destroying the model', ->
+    it 'emits a did-destroy event', ->
+      spy = jasmine.createSpy('destroy')
+      minimap.onDidDestroy(spy)
+
+      minimap.destroy()
+
+      expect(spy).toHaveBeenCalled()
+
+    it 'returns true when asked if destroyed', ->
+      minimap.destroy()
+      expect(minimap.isDestroyed()).toBeTruthy()
+
+  describe 'destroying the text editor', ->
+    it 'destroys the model', ->
+      spyOn(minimap,'destroy')
+
+      editor.destroy()
+
+      expect(minimap.destroy).toHaveBeenCalled()
+
   #    ########  ########  ######   #######
   #    ##     ## ##       ##    ## ##     ##
   #    ##     ## ##       ##       ##     ##