Fix FileManager thread panic and other misc improvements

- Add shut down logic for FileManager thread
- Add an unit test for filemanager_thread

tests/unit/net/filemanager_thread.rs

@@ -0,0 +1,34 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use ipc_channel::ipc::{self, IpcSender};
+use net::filemanager_thread::FileManagerThreadFactory;
+use net_traits::filemanager_thread::{FileManagerThreadMsg, FileManagerThreadError};
+
+#[test]
+fn test_filemanager() {
+    let chan: IpcSender<FileManagerThreadMsg> = FileManagerThreadFactory::new();
+
+    {
+        let (tx, rx) = ipc::channel().unwrap();
+        let _ = chan.send(FileManagerThreadMsg::SelectFile(tx));
+
+        match rx.recv().unwrap() {
+            Err(FileManagerThreadError::InvalidSelection) => {},
+            _ => assert!(false, "Should be an invalid selection before dialog is implemented"),
+        }
+    }
+
+    let _ = chan.send(FileManagerThreadMsg::Exit);
+
+    {
+        let (tx, rx) = ipc::channel().unwrap();
+        let _ = chan.send(FileManagerThreadMsg::SelectFile(tx));
+
+        match rx.try_recv() {
+            Ok(_) => assert!(false, "The thread should not response fine after exited"),
+            Err(_) => {},
+        }
+    }
+}