Add Buffer.save

spec/atom/buffer-spec.coffee

@@ -3,11 +3,47 @@ fs = require 'fs'
 
 describe 'Buffer', ->
   describe 'constructor', ->
-    it "loads the contents of the given url", ->
-      filePath = require.resolve 'fixtures/sample.txt'
-      buffer = new Buffer filePath
-      expect(buffer.getText()).toBe fs.read(filePath)
+    describe "when given a url", ->
+      describe "when a file exists for the url", ->
+        it "loads the contents of that file", ->
+          filePath = require.resolve 'fixtures/sample.txt'
+          buffer = new Buffer filePath
+          expect(buffer.getText()).toBe fs.read(filePath)
+
+      describe "when no file exists for the url", ->
+        it "creates an empty buffer", ->
+          filePath = "does-not-exist.txt"
+          expect(fs.exists(filePath)).toBeFalsy()
+
+          buffer = new Buffer filePath
+          expect(buffer.getText()).toBe ""
+
+    describe "when no url is given", ->
+      it "creates an empty buffer", ->
+        buffer = new Buffer null
+        expect(buffer.getText()).toBe ""
+
+  describe "save", ->
+    describe "when the buffer has a url", ->
+      filePath = null
+
+      beforeEach ->
+        filePath = require.resolve('fixtures') + '/temp.txt'
+        expect(fs.exists(filePath)).toBeFalsy()
+
+      afterEach ->
+        fs.remove filePath
+
+      it "saves the contents of the buffer to the url", ->
+        buffer = new Buffer filePath
+        buffer.setText 'Buffer contents!'
+        buffer.save()
+        expect(fs.read(filePath)).toEqual 'Buffer contents!'
+
+    describe "when the buffer no url", ->
+      it "throw an exception", ->
+        buffer = new Buffer
+        expect(-> buffer.save()).toThrow()
+
+
 
-    it "loads an empty buffer if no url is given", ->
-      buffer = new Buffer null
-      expect(buffer.getText()).toBe ""

src/atom/buffer.coffee

@@ -7,9 +7,18 @@ class Buffer
   url: null
 
   constructor: (@url) ->
-    text = if @url then fs.read(@url) else ""
+    text = if @url and fs.exists(@url)
+      fs.read(@url)
+    else
+      ""
     @aceDocument = new Document text
 
   getText: ->
     @aceDocument.getValue()
 
+  setText: (text) ->
+    @aceDocument.setValue text
+
+  save: ->
+    if not @url then throw new Error("Tried to save buffer with no url")
+    fs.write @url, @getText()

src/atom/editor.coffee

@@ -25,4 +25,3 @@ class Editor
   getAceSession: ->
     @aceEditor.getSession()
 
-

src/stdlib/fs.coffee

@@ -67,6 +67,12 @@ module.exports =
   listDirectoryTree: (path) ->
     @list path, true
 
+  # Remove a file at the given path. Throws an error if path is not a
+  # file or a symbolic link to a file.
+  remove: (path) ->
+    fm = OSX.NSFileManager.defaultManager
+    paths = fm.removeItemAtPath_error path, null
+
   # Open, read, and close a file, returning the file's contents.
   read: (path) ->
     path = @absolute path