Uninstall packages not listed in packages.cson

README.md

@@ -42,6 +42,7 @@ Where the contents of the array is a list of packages to ensure are installed.
 
 * `createOnChange` — Create the package list when packages are installed or removed via the Atom settings. You must restart Atom after installing Package Sync for this setting to take effect, and it works best when paired with the `forceOverwrite` setting.
 * `forceOverwrite` — Forces the `create-package-list` command to overwrite the `packages.cson` if it exists.
+* `uninstall` — Uninstall packages missing from the `package.cson` on sync.
 
 ### Commands
 

lib/index.coffee

@@ -42,3 +42,8 @@ module.exports =
       description: 'Create package list when packages are installed or removed.'
       type: 'boolean'
       default: false
+    uninstall:
+      title: 'Uninstall packages on sync'
+      description: 'Uninstall packages not listed in packages.cson on sync.'
+      type: 'boolean'
+      default: false

lib/package-sync.coffee

@@ -27,6 +27,9 @@ class PackageSync
   # Internal: Packages in the process of being installed.
   packagesToInstall: []
 
+  # Internal: Packages in the process of being uninstalled.
+  packagesToUninstall: []
+
   # Internal: Timeout for messages that should be up for only a short time.
   shortMessageTimeout: 1000
 
@@ -41,11 +44,16 @@ class PackageSync
   openPackageList: ->
     atom.workspace.open(PackageList.getPackageListPath())
 
-  # Public: Installs any packages that are missing from the `packages.cson` configuration file.
+  # Public: Installs any packages that are missing from the `packages.cson` configuration file,
+  # and optionally uninstalls any packages that are installed but not in `packages.cson`.
   sync: ->
-    missing = @getMissingPackages()
+    missing = @getMissingPackages(false)
     @installPackages(missing)
 
+    if atom.config.get('package-sync.uninstall')
+      uninstall = @getMissingPackages(true)
+      @uninstallPackages(uninstall)
+
   # Internal: Displays a message in the status bar.
   #
   # If `timeout` is specified, the message will automatically be cleared in `timeout` milliseconds.
@@ -65,20 +73,20 @@ class PackageSync
   # Internal: Execute APM to install the given package.
   #
   # pkg - A {String} containing the name of the package to install.
-  executeApm: (pkg) ->
-    @displayMessage("Installing #{pkg}")
+  executeApm: (action, pkg) ->
+    @displayMessage("#{if action == "install" then "Install" else "Uninstall"}ing #{pkg}")
     command = @apmPath
-    args = ['install', pkg]
+    args = [action, pkg]
     stdout = (output) ->
     stderr = (output) ->
     exit = (exitCode) =>
       if exitCode is 0
-        if @packagesToInstall.length > 0
-          @displayMessage("#{pkg} installed!", @shortMessageTimeout)
+        if @packagesToInstall.length > 0 or @packagesToUninstall.length > 0
+          @displayMessage("#{pkg} #{action}ed!", @shortMessageTimeout)
         else
           @displayMessage('Package Sync complete!', @longMessageTimeout)
       else
-        @displayMessage("An error occurred installing #{pkg}", @longMessageTimeout)
+        @displayMessage("An error occurred #{action}ing #{pkg}", @longMessageTimeout)
 
       @currentInstall = null
       @installPackage()
@@ -87,19 +95,30 @@ class PackageSync
 
   # Internal: Gets the list of packages that are missing.
   #
+  # uninstall - A {Boolean} indicating whether to install packages in the list
+  # but missing from Atom (false), or uninstall packages in Atom but missing
+  # from the list (true).
+  #
   # Returns an {Array} of names of packages that need to be installed.
-  getMissingPackages: ->
+  getMissingPackages: (uninstall = false) ->
     list = new PackageList()
     syncPackages = list.getPackages()
-    availablePackages = atom.packages.getAvailablePackageNames()
-    value for value in syncPackages when value not in availablePackages
+
+    # Only compare against the list of non-bundled packages
+    availablePackageNames = atom.packages.getAvailablePackageNames()
+    availablePackages = (pkg for pkg in availablePackageNames when not atom.packages.isBundledPackage(pkg))
+
+    if uninstall
+      value for value in availablePackages when value not in syncPackages
+    else
+      value for value in syncPackages when value not in availablePackages
 
   # Internal: Installs the next package in the list.
   installPackage: ->
     # Exit if there is already an installation running or if there are no more
     # packages to install.
     return if @currentInstall? or @packagesToInstall.length is 0
-    @executeApm(@packagesToInstall.shift())
+    @executeApm("install", @packagesToInstall.shift())
 
   # Internal: Installs each of the packages in the given list.
   #
@@ -108,6 +127,20 @@ class PackageSync
     @packagesToInstall.push(packages...)
     @installPackage()
 
+  # Internal: Uninstalls the next package in the list.
+  uninstallPackage: ->
+    # Exit if there is already an installation running or if there are no more
+    # packages to uninstall.
+    return if @currentInstall? or @packagesToUninstall.length is 0
+    @executeApm("uninstall", @packagesToUninstall.shift())
+
+  # Internal: Uninstalls each of the packages in the given list.
+  #
+  # packages - An {Array} containing the names of packages to uninstall.
+  uninstallPackages: (packages) ->
+    @packagesToUninstall.push(packages...)
+    @uninstallPackage()
+
   # Internal: Sets a timeout to remove the status bar message.
   #
   # timeout - The {Number} of milliseconds until the message should be removed.

spec/package-sync-spec.coffee

@@ -23,4 +23,11 @@ describe 'PackageSync', ->
       spyOn(atom, 'getConfigDirPath').andReturn(os.tmpdir())
       spyOn(atom.packages, 'getAvailablePackageNames').andReturn(['foo'])
 
-      expect(@sync.getMissingPackages()).toEqual(['bar', 'baz'])
+      expect(@sync.getMissingPackages(false)).toEqual(['bar', 'baz'])
+
+    it 'gets a list of installed packages, excluding ones that are in the list', ->
+      h.createPackages({'packages': ['foo', 'bar']})
+      spyOn(atom, 'getConfigDirPath').andReturn(os.tmpdir())
+      spyOn(atom.packages, 'getAvailablePackageNames').andReturn(['foo', 'bar', 'baz'])
+
+      expect(@sync.getMissingPackages(true)).toEqual(['baz'])