Add PackageManager::onDidLoad/UnloadPackage

Signed-off-by: Max Brunsfeld <maxbrunsfeld@gmail.com>

spec/package-manager-spec.coffee

@@ -34,6 +34,14 @@ describe "PackageManager", ->
       expect(console.warn.callCount).toBe(1)
       expect(console.warn.argsForCall[0][0]).toContain("Could not resolve")
 
+    it "invokes ::onDidLoadPackage listeners with the loaded package", ->
+      loadedPackage = null
+      atom.packages.onDidLoadPackage (pack) -> loadedPackage = pack
+
+      atom.packages.loadPackage("package-with-main")
+
+      expect(loadedPackage.name).toBe "package-with-main"
+
   describe "::unloadPackage(name)", ->
     describe "when the package is active", ->
       it "throws an error", ->
@@ -61,6 +69,13 @@ describe "PackageManager", ->
         atom.packages.unloadPackage(pack.name)
         expect(atom.packages.isPackageLoaded(pack.name)).toBeFalsy()
 
+    it "invokes ::onDidUnloadPackage listeners with the unloaded package", ->
+      atom.packages.loadPackage('package-with-main')
+      unloadedPackage = null
+      atom.packages.onDidUnloadPackage (pack) -> unloadedPackage = pack
+      atom.packages.unloadPackage('package-with-main')
+      expect(unloadedPackage.name).toBe 'package-with-main'
+
   describe "::activatePackage(id)", ->
     describe "when called multiple times", ->
       it "it only calls activate on the package once", ->

src/package-manager.coffee

@@ -90,6 +90,24 @@ class PackageManager
   onDidDeactivatePackage: (callback) ->
     @emitter.on 'did-deactivate-package', callback
 
+  # Public: Invoke the given callback when a package is loaded.
+  #
+  # * `callback` A {Function} to be invoked when a package is loaded.
+  #   * `package` The {Package} that was loaded.
+  #
+  # Returns a {Disposable} on which `.dispose()` can be called to unsubscribe.
+  onDidLoadPackage: (callback) ->
+    @emitter.on 'did-load-package', callback
+
+  # Public: Invoke the given callback when a package is unloaded.
+  #
+  # * `callback` A {Function} to be invoked when a package is unloaded.
+  #   * `package` The {Package} that was unloaded.
+  #
+  # Returns a {Disposable} on which `.dispose()` can be called to unsubscribe.
+  onDidUnloadPackage: (callback) ->
+    @emitter.on 'did-unload-package', callback
+
   on: (eventName) ->
     switch eventName
       when 'loaded'
@@ -321,6 +339,7 @@ class PackageManager
           pack = new Package(packagePath, metadata)
         pack.load()
         @loadedPackages[pack.name] = pack
+        @emitter.emit 'did-load-package', pack
         return pack
       catch error
         console.warn "Failed to load package.json '#{path.basename(packagePath)}'", error.stack ? error
@@ -338,6 +357,7 @@ class PackageManager
 
     if pack = @getLoadedPackage(name)
       delete @loadedPackages[pack.name]
+      @emitter.emit 'did-unload-package', pack
     else
       throw new Error("No loaded package for name '#{name}'")