Refactor audio file player

- Do not play if there is no context available (e.g. unit testing)

test/api_test.dart

@@ -39,6 +39,30 @@ void main() {
 
     });
 
+    test("Login Failure", () async {
+      // Tests for various types of login failures
+      var api = InvenTreeAPI();
+
+      // Incorrect server address
+      var profile = await UserProfileDBManager().getSelectedProfile();
+
+      assert(profile != null);
+
+      if (profile != null) {
+        profile.server = "http://localhost:5555";
+        await UserProfileDBManager().updateProfile(profile);
+      }
+
+      bool result = await api.connectToServer();
+
+      assert(!result);
+
+      // TODO: Test the the right 'error message' is returned
+
+      // TODO: Test incorrect login details
+
+    });
+
     test("Login Success", () async {
       // Test that we can login to the server successfully
       var api = InvenTreeAPI();
@@ -46,10 +70,13 @@ void main() {
       // Attempt to connect
       final bool result = await api.connectToServer();
 
+      // Check expected values
       expect(result, equals(true));
       expect(api.hasToken, equals(true));
-
       expect(api.baseUrl, equals("http://localhost:12345/"));
+
+      expect(api.isConnected(), equals(true));
+      expect(api.isConnecting(), equals(false));
     });
   });
 }