Merge pull request #9711 from atom/as-is-text-editor

Export ::isTextEditor function

exports/atom.coffee

@@ -35,7 +35,6 @@ unless process.env.ATOM_SHELL_INTERNAL_RUN_AS_NODE
         The `TextEditor` constructor is no longer public.
 
         To construct a text editor, use `atom.workspace.buildTextEditor()`.
-        To check if an object is a text editor, look for for the existence of
-        a public method that you're using (e.g. `::getText`).
+        To check if an object is a text editor, use `atom.workspace.isTextEditor(object)`.
       """
       TextEditor

spec/workspace-spec.coffee

@@ -658,6 +658,13 @@ describe "Workspace", ->
       waitsForPromise -> workspace.openLicense()
       runs -> expect(workspace.getActivePaneItem().getText()).toMatch /Copyright/
 
+  describe "::isTextEditor(obj)", ->
+    it "returns true when the passed object is an instance of `TextEditor`", ->
+      expect(workspace.isTextEditor(atom.workspace.buildTextEditor())).toBe(true)
+      expect(workspace.isTextEditor({getText: ->})).toBe(false)
+      expect(workspace.isTextEditor(null)).toBe(false)
+      expect(workspace.isTextEditor(undefined)).toBe(false)
+
   describe "::observeTextEditors()", ->
     it "invokes the observer with current and future text editors", ->
       observed = []

src/workspace.coffee

@@ -518,6 +518,12 @@ class Workspace extends Model
     @project.bufferForPath(filePath, options).then (buffer) =>
       @buildTextEditor(_.extend({buffer, largeFileMode}, options))
 
+  # Public: Returns a {Boolean} that is `true` if `object` is a `TextEditor`.
+  #
+  # * `object` An {Object} you want to perform the check against.
+  isTextEditor: (object) ->
+    object instanceof TextEditor
+
   # Extended: Create a new text editor.
   #
   # Returns a {TextEditor}.