Add toBeInstanceOf and toHaveLength jasmine matchers

spec/spec-helper.coffee

@@ -68,6 +68,8 @@ beforeEach ->
   spyOn($native, 'writeToPasteboard').andCallFake (text) -> pasteboardContent = text
   spyOn($native, 'readFromPasteboard').andCallFake -> pasteboardContent
 
+  addCustomMatchers(this)
+
 afterEach ->
   keymap.bindingSets = bindingSetsToRestore
   keymap.bindingSetsByFirstKeystrokeToRestore = bindingSetsByFirstKeystrokeToRestore
@@ -121,6 +123,18 @@ jasmine.unspy = (object, methodName) ->
   throw new Error("Not a spy") unless object[methodName].originalValue?
   object[methodName] = object[methodName].originalValue
 
+addCustomMatchers = (spec) ->
+  spec.addMatchers
+    toBeInstanceOf: (expected) ->
+      notText = if @isNot then " not" else ""
+      this.message = => "Expected #{jasmine.pp(@actual)} to#{notText} be instance of #{expected.name} class"
+      @actual instanceof expected
+
+    toHaveLength: (expected) ->
+      notText = if @isNot then " not" else ""
+      this.message = => "Expected object with length #{@actual.length} to#{notText} have length #{expected}"
+      @actual.length == expected
+
 window.keyIdentifierForKey = (key) ->
   if key.length > 1 # named key
     key

src/packages/markdown-preview/spec/markdown-preview-spec.coffee

@@ -1,14 +1,72 @@
 $ = require 'jquery'
 RootView = require 'root-view'
-MarkdownPreview = require 'markdown-preview/lib/markdown-preview-view'
+MarkdownPreviewView = require 'markdown-preview/lib/markdown-preview-view'
 _ = require 'underscore'
 
-describe "MarkdownPreview", ->
+describe "MarkdownPreviewView", ->
   beforeEach ->
     project.setPath(project.resolve('markdown'))
     window.rootView = new RootView
     window.loadPackage("markdown-preview")
-    spyOn(MarkdownPreview.prototype, 'loadHtml')
+    spyOn(MarkdownPreviewView.prototype, 'loadHtml')
+
+  fdescribe "markdown-preview:show", ->
+    beforeEach ->
+      rootView.open("file.markdown")
+
+    describe "when the active item is an edit session", ->
+      beforeEach ->
+        rootView.attachToDom()
+
+      describe "when a preview item has not been created for the edit session's uri", ->
+        describe "when there is more than one pane", ->
+          it "shows a markdown preview for the current buffer on the next pane", ->
+            rootView.getActivePane().splitRight()
+            [pane1, pane2] = rootView.getPanes()
+            pane1.focus()
+
+            rootView.getActiveView().trigger 'markdown-preview:show'
+
+            preview = pane2.activeItem
+            expect(preview).toBeInstanceOf(MarkdownPreviewView)
+            expect(preview.buffer).toBe rootView.getActivePaneItem().buffer
+            expect(pane1).toMatchSelector(':has(:focus)')
+
+        describe "when there is only one pane", ->
+          it "splits the current pane to the right with a markdown preview for the current buffer", ->
+            expect(rootView.getPanes()).toHaveLength 1
+
+            rootView.getActiveView().trigger 'markdown-preview:show'
+
+            expect(rootView.getPanes()).toHaveLength 2
+            [pane1, pane2] = rootView.getPanes()
+
+            expect(pane2.items).toHaveLength 1
+            preview = pane2.activeItem
+            expect(preview).toBeInstanceOf(MarkdownPreviewView)
+            expect(preview.buffer).toBe rootView.getActivePaneItem().buffer
+            expect(pane1).toMatchSelector(':has(:focus)')
+
+      describe "when a preview item has already been created for the edit session's uri", ->
+        it "updates and shows the existing preview item if it isn't displayed", ->
+          rootView.getActiveView().trigger 'markdown-preview:show'
+          [pane1, pane2] = rootView.getPanes()
+          pane2.focus()
+          expect(rootView.getActivePane()).toBe pane2
+          preview = pane2.activeItem
+          expect(preview).toBeInstanceOf(MarkdownPreviewView)
+          rootView.open()
+          expect(pane2.activeItem).not.toBe preview
+          pane1.focus()
+
+          rootView.getActiveView().trigger 'markdown-preview:show'
+          expect(rootView.getPanes()).toHaveLength 2
+          expect(pane2.getItems()).toHaveLength 2
+          expect(pane2.activeItem).toBe preview
+          expect(pane1).toMatchSelector(':has(:focus)')
+
+    describe "when the active item is not an edit session ", ->
+      it "logs a warning to the console saying that it isn't possible to preview the item", ->
 
   describe "markdown-preview:toggle event", ->
     it "toggles on/off a preview for a .md file", ->
@@ -50,7 +108,7 @@ describe "MarkdownPreview", ->
       expect(rootView.find('.markdown-preview')).not.toExist()
       editor.trigger('markdown-preview:toggle')
       expect(rootView.find('.markdown-preview')).not.toExist()
-      expect(MarkdownPreview.prototype.loadHtml).not.toHaveBeenCalled()
+      expect(MarkdownPreviewView.prototype.loadHtml).not.toHaveBeenCalled()
 
   describe "core:cancel event", ->
    it "removes markdown preview", ->