Added unit tests for all the new widgets

src/ui/widgets/error_message_tests.rs

@@ -0,0 +1,14 @@
+#[cfg(test)]
+mod tests {
+  use crate::ui::widgets::error_message::ErrorMessage;
+  use pretty_assertions::assert_eq;
+  use ratatui::text::Text;
+
+  #[test]
+  fn test_error_message_new() {
+    let message = "This is an error message";
+    let error_message = ErrorMessage::new(message);
+
+    assert_eq!(error_message.text, Text::from(message));
+  }
+}