adds a test for ProjectManager.shouldShow.

Also corrects a bug with pull request #2366

src/project/ProjectManager.js

@@ -556,12 +556,17 @@ define(function (require, exports, module) {
         return result.promise();
     }
 
-    /** @param {Entry} entry File or directory to filter */
+    /**
+     * Returns false for files and directories that are not commonly useful to display.
+     *
+     * @param {Entry} entry File or directory to filter
+     * @return boolean true if the file should be displayed
+     */
     function shouldShow(entry) {
         if ([".git", ".gitignore", ".gitmodules", ".svn", ".DS_Store", "Thumbs.db"].indexOf(entry.name) > -1) {
             return false;
         }
-        var extension = entry.name.split('.').slice(-1);
+        var extension = entry.name.split('.').pop();
         if (["pyc"].indexOf(extension) > -1) {
             return false;
         }

test/spec/ProjectManager-test.js

@@ -168,6 +168,20 @@ define(function (require, exports, module) {
                 }
             });
         });
+
+        describe("File Display", function () {
+            it("should not show useless directory entries", function () {
+                var shouldShow = ProjectManager.shouldShow;
+                var makeEntry = function (name) {
+                    return { name: name };
+                };
+
+                expect(shouldShow(makeEntry(".gitmodules"))).toBe(false);
+                expect(shouldShow(makeEntry("foobar"))).toBe(true);
+                expect(shouldShow(makeEntry("pyc.py"))).toBe(true);
+                expect(shouldShow(makeEntry("module.pyc"))).toBe(false);
+            });
+        });
 
     });
 });