Render empty lines correctly when inserting newlines

spec/atom/editor-spec.coffee

@@ -218,7 +218,7 @@ describe "Editor", ->
       expect(editor).not.toMatchSelector ':focus'
       expect(editor.hiddenInput).toMatchSelector ':focus'
 
-  describe "when text input events are triggered on the hidden input element", ->
+  fdescribe "when text input events are triggered on the hidden input element", ->
     it "inserts the typed character at the cursor position, both in the buffer and the pre element", ->
       editor.setPosition(row: 1, col: 6)
 
@@ -230,3 +230,35 @@ describe "Editor", ->
       expect(editor.getPosition()).toEqual(row: 1, col: 7)
       expect(editor.lines.find('pre:eq(1)')).toHaveText editor.getCurrentLine()
 
+  fdescribe "when return is pressed", ->
+    describe "when the cursor is at the beginning of a line", ->
+      it "inserts an empty line before it", ->
+        editor.setPosition(row: 1, col: 0)
+
+        editor.trigger keydownEvent('enter')
+
+        expect(editor.lines.find('pre:eq(1)')).toHaveHtml ' '
+        expect(editor.getPosition()).toEqual(row: 2, col: 0)
+
+    describe "when the cursor is in the middle of a line", ->
+      it "splits the current line to form a new line", ->
+        editor.setPosition(row: 1, col: 6)
+
+        originalLine = editor.lines.find('pre:eq(1)').text()
+        lineBelowOriginalLine = editor.lines.find('pre:eq(2)').text()
+        editor.trigger keydownEvent('enter')
+
+        expect(editor.lines.find('pre:eq(1)')).toHaveText originalLine[0...6]
+        expect(editor.lines.find('pre:eq(2)')).toHaveText originalLine[6..]
+        expect(editor.lines.find('pre:eq(3)')).toHaveText lineBelowOriginalLine
+        expect(editor.getPosition()).toEqual(row: 2, col: 0)
+
+    describe "when the cursor is on the end of a line", ->
+      it "inserts an empty line after it", ->
+        editor.setPosition(row: 1, col: buffer.getLine(1).length)
+
+        editor.trigger keydownEvent('enter')
+
+        expect(editor.lines.find('pre:eq(2)')).toHaveHtml ' '
+        expect(editor.getPosition()).toEqual(row: 2, col: 0)
+      

src/atom/cursor.coffee

@@ -13,7 +13,10 @@ class Cursor extends Template
 
     setBuffer: (@buffer) ->
       @buffer.on 'insert', (e) =>
-        @setColumn(@getColumn() + e.string.length)
+        if e.string == "\n"
+          @setPosition {row: @getRow() + 1, col: 0}
+        else
+          @setColumn(@getColumn() + e.string.length)
 
     setPosition: (point) ->
       @point = @editor.clipPosition(point)
@@ -29,6 +32,9 @@ class Cursor extends Template
     getColumn: ->
       @getPosition().col
 
+    getRow: ->
+      @getPosition().row
+
     moveUp: ->
       { row, col } = @getPosition()
       col = @goalColumn if @goalColumn?

src/atom/editor.coffee

@@ -34,11 +34,13 @@ class Editor extends Template
         left: 'move-left'
         down: 'move-down'
         up: 'move-up'
+        enter: 'newline'
 
       @on 'move-right', => @moveRight()
       @on 'move-left', => @moveLeft()
       @on 'move-down', => @moveDown()
       @on 'move-up', => @moveUp()
+      @on 'newline', => @buffer.insert @getPosition(), "\n"
 
     handleEvents: ->
       @on 'focus', =>
@@ -52,18 +54,27 @@ class Editor extends Template
         @calculateDimensions()
         @focus()
 
+    buildLineElement: (lineText) ->
+      if lineText is ''
+        $$.pre -> @raw(' ')
+      else
+        $$.pre(lineText)
+
     setBuffer: (@buffer) ->
       @lines.empty()
       for line in @buffer.getLines()
-        if line is ''
-          @lines.append $$.pre -> @raw(' ')
-        else
-          @lines.append $$.pre(line)
+        @lines.append @buildLineElement(line)
+
       @setPosition(row: 0, col: 0)
       @cursor.setBuffer(@buffer)
+
       @buffer.on 'insert', (e) =>
         {row} = e.range.start
-        @lines.find('pre').eq(row).replaceWith $$.pre(@buffer.getLine(row))
+
+        updatedLine = @buildLineElement(@buffer.getLine(row))
+        @lines.find('pre').eq(row).replaceWith(updatedLine)
+        if e.string == '\n'
+          updatedLine.after @buildLineElement(@buffer.getLine(row + 1))
 
     clipPosition: ({row, col}) ->
       line = @buffer.getLine(row)