         let outputPlist = try! NSPropertyListSerialization.propertyListWithData(outputData,
                                                                                 options: .Immutable,
                                                                                 format: nil)
-
+        
         let entities = outputPlist["system-entities"] as AnyObject as! [[String:AnyObject]]
         let hfsEntry = entities.filter{ $0["content-hint"] as! String == "Apple_HFS" }.first!
         let mountPoint = hfsEntry["mount-point"] as! String

        XCTAssertTrue(writeSuccessful, "Failed to update archive on external volume")
    }
    
    func createDMG(path dmgURL: NSURL, source: NSURL) {
        let task = NSTask()
        task.launchPath = "/usr/bin/hdiutil"
        task.arguments = ["create",
                          "-fs", "HFS+",
                          "-volname", dmgURL.URLByDeletingPathExtension!.lastPathComponent!,
                          "-srcfolder", source.path!,
                          dmgURL.path!]

        task.launch()
        task.waitUntilExit()
        
        if task.terminationStatus != 0 {
            NSLog("Failed to create DMG: \(dmgURL.path!)");
        }
    }
    
    func mountDMG(dmgURL: NSURL) -> String? {
        let task = NSTask()
        task.launchPath = "/usr/bin/hdiutil"
        task.arguments = ["attach", "-plist", dmgURL.path!]
        
        let outputPipe = NSPipe()
        task.standardOutput = outputPipe
        
        task.launch()
        task.waitUntilExit()
        
        if task.terminationStatus != 0 {
            NSLog("Failed to attach DMG: \(dmgURL.path!)");
            return nil
        }
        

        let tempZipFileURL = self.archiveWithFiles([textFileURL])
        NSLog("Original ZIP file: \(tempZipFileURL.path!)")
        
        // Write that zip file to contents of a DMG and mount it
        let dmgSourceFolderURL = tempDirURL.URLByAppendingPathComponent("DMGSource")
        try! NSFileManager.defaultManager().createDirectoryAtURL(dmgSourceFolderURL, withIntermediateDirectories: true, attributes: [:])
        try! NSFileManager.defaultManager().copyItemAtURL(tempZipFileURL, toURL: dmgSourceFolderURL.URLByAppendingPathComponent(tempZipFileURL.lastPathComponent!))
        let dmgURL = tempDirURL.URLByAppendingPathComponent("testWriteData_ExternalVolume.dmg")
        let mountPoint = createAndMountDMG(path: dmgURL, source: dmgSourceFolderURL)!
        NSLog("Disk image: \(dmgURL.path!)")
        
        // Update a file from the archive with overwrite=YES
        let externalVolumeZipURL = NSURL(fileURLWithPath: mountPoint).URLByAppendingPathComponent(tempZipFileURL.lastPathComponent!)
