diff --git a/editor/src/utility_types.rs b/editor/src/utility_types.rs
index c80271f5cb..51bc59151a 100644
--- a/editor/src/utility_types.rs
+++ b/editor/src/utility_types.rs
@@ -108,3 +108,311 @@ impl DebugMessageTree {
 		self.message_handler.as_ref()
 	}
 }
+
+// ============================================================
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+
+	// Helper: creates a standard MessageData for reuse
+	fn sample_message_data() -> MessageData {
+		MessageData::new("TestMessage".to_string(), vec![("field_one".to_string(), 1), ("field_two".to_string(), 2)], "src/messages.rs", 42)
+	}
+
+	// MessageData Tests
+
+	#[test]
+	fn test_message_data_new_stores_name() {
+		let msg = sample_message_data();
+		assert_eq!(msg.name(), "TestMessage");
+	}
+
+	#[test]
+	fn test_message_data_new_stores_fields() {
+		let msg = sample_message_data();
+		let fields = msg.fields();
+		assert_eq!(fields.len(), 2);
+		assert_eq!(fields[0], ("field_one".to_string(), 1));
+		assert_eq!(fields[1], ("field_two".to_string(), 2));
+	}
+
+	#[test]
+	fn test_message_data_new_stores_path() {
+		let msg = sample_message_data();
+		assert_eq!(msg.path(), "src/messages.rs");
+	}
+
+	#[test]
+	fn test_message_data_new_stores_line_number() {
+		let msg = sample_message_data();
+		assert_eq!(msg.line_number(), 42);
+	}
+
+	#[test]
+	fn test_message_data_empty_fields() {
+		let msg = MessageData::new("Empty".to_string(), vec![], "src/lib.rs", 0);
+		assert!(msg.fields().is_empty());
+	}
+
+	#[test]
+	fn test_message_data_zero_line_number() {
+		let msg = MessageData::new("ZeroLine".to_string(), vec![], "src/lib.rs", 0);
+		assert_eq!(msg.line_number(), 0);
+	}
+
+	#[test]
+	fn test_message_data_large_line_number() {
+		let msg = MessageData::new("BigLine".to_string(), vec![], "src/lib.rs", usize::MAX);
+		assert_eq!(msg.line_number(), usize::MAX);
+	}
+
+	#[test]
+	fn test_message_data_name_empty_string() {
+		let msg = MessageData::new("".to_string(), vec![], "src/lib.rs", 1);
+		assert_eq!(msg.name(), "");
+	}
+
+	#[test]
+	fn test_message_data_fields_large_value() {
+		let msg = MessageData::new("Big".to_string(), vec![("huge".to_string(), usize::MAX)], "src/lib.rs", 1);
+		assert_eq!(msg.fields()[0].1, usize::MAX);
+	}
+
+	#[test]
+	fn test_message_data_debug_format() {
+		let msg = sample_message_data();
+		let debug_str = format!("{:?}", msg);
+		// Debug output should contain the name
+		assert!(debug_str.contains("TestMessage"));
+	}
+
+	// DebugMessageTree Tests
+
+	#[test]
+	fn test_debug_message_tree_new_sets_name() {
+		let tree = DebugMessageTree::new("RootNode");
+		assert_eq!(tree.name(), "RootNode");
+	}
+
+	#[test]
+	fn test_debug_message_tree_new_fields_is_none() {
+		let tree = DebugMessageTree::new("RootNode");
+		assert!(tree.fields().is_none());
+	}
+
+	#[test]
+	fn test_debug_message_tree_new_variants_is_none() {
+		let tree = DebugMessageTree::new("RootNode");
+		assert!(tree.variants().is_none());
+	}
+
+	#[test]
+	fn test_debug_message_tree_new_message_handler_is_none() {
+		let tree = DebugMessageTree::new("RootNode");
+		assert!(tree.message_handler_fields().is_none());
+	}
+
+	#[test]
+	fn test_debug_message_tree_new_message_handler_data_is_none() {
+		let tree = DebugMessageTree::new("RootNode");
+		assert!(tree.message_handler_data_fields().is_none());
+	}
+
+	#[test]
+	fn test_debug_message_tree_new_path_is_empty() {
+		let tree = DebugMessageTree::new("RootNode");
+		assert_eq!(tree.path(), "");
+	}
+
+	#[test]
+	fn test_debug_message_tree_new_line_number_is_zero() {
+		let tree = DebugMessageTree::new("RootNode");
+		assert_eq!(tree.line_number(), 0);
+	}
+
+	// add_fields() Tests
+
+	#[test]
+	fn test_add_fields_sets_fields() {
+		let mut tree = DebugMessageTree::new("Node");
+		tree.add_fields(vec!["alpha".to_string(), "beta".to_string()]);
+		let fields = tree.fields().expect("fields should be Some");
+		assert_eq!(fields.len(), 2);
+		assert_eq!(fields[0], "alpha");
+		assert_eq!(fields[1], "beta");
+	}
+
+	#[test]
+	fn test_add_fields_empty_vec() {
+		let mut tree = DebugMessageTree::new("Node");
+		tree.add_fields(vec![]);
+		let fields = tree.fields().expect("fields should be Some even if empty");
+		assert!(fields.is_empty());
+	}
+
+	#[test]
+	fn test_add_fields_overwrites_previous() {
+		let mut tree = DebugMessageTree::new("Node");
+		tree.add_fields(vec!["first".to_string()]);
+		tree.add_fields(vec!["second".to_string(), "third".to_string()]);
+		let fields = tree.fields().expect("fields should be Some");
+		assert_eq!(fields, &vec!["second".to_string(), "third".to_string()]);
+	}
+
+	// set_path() Tests
+
+	#[test]
+	fn test_set_path_updates_path() {
+		let mut tree = DebugMessageTree::new("Node");
+		tree.set_path("editor/src/dispatcher.rs");
+		assert_eq!(tree.path(), "editor/src/dispatcher.rs");
+	}
+
+	#[test]
+	fn test_set_path_empty_string() {
+		let mut tree = DebugMessageTree::new("Node");
+		tree.set_path("");
+		assert_eq!(tree.path(), "");
+	}
+
+	#[test]
+	fn test_set_path_overwrite() {
+		let mut tree = DebugMessageTree::new("Node");
+		tree.set_path("old/path.rs");
+		tree.set_path("new/path.rs");
+		assert_eq!(tree.path(), "new/path.rs");
+	}
+
+	// set_line_number() Tests
+
+	#[test]
+	fn test_set_line_number_updates_value() {
+		let mut tree = DebugMessageTree::new("Node");
+		tree.set_line_number(99);
+		assert_eq!(tree.line_number(), 99);
+	}
+
+	#[test]
+	fn test_set_line_number_zero() {
+		let mut tree = DebugMessageTree::new("Node");
+		tree.set_line_number(0);
+		assert_eq!(tree.line_number(), 0);
+	}
+
+	#[test]
+	fn test_set_line_number_overwrite() {
+		let mut tree = DebugMessageTree::new("Node");
+		tree.set_line_number(10);
+		tree.set_line_number(200);
+		assert_eq!(tree.line_number(), 200);
+	}
+
+	#[test]
+	fn test_set_line_number_max_value() {
+		let mut tree = DebugMessageTree::new("Node");
+		tree.set_line_number(usize::MAX);
+		assert_eq!(tree.line_number(), usize::MAX);
+	}
+
+	// add_variant() Tests
+
+	#[test]
+	fn test_add_variant_first_variant_creates_vec() {
+		let mut tree = DebugMessageTree::new("Root");
+		let child = DebugMessageTree::new("Child");
+		tree.add_variant(child);
+		let variants = tree.variants().expect("variants should be Some");
+		assert_eq!(variants.len(), 1);
+		assert_eq!(variants[0].name(), "Child");
+	}
+
+	#[test]
+	fn test_add_variant_multiple_variants() {
+		let mut tree = DebugMessageTree::new("Root");
+		tree.add_variant(DebugMessageTree::new("Child1"));
+		tree.add_variant(DebugMessageTree::new("Child2"));
+		tree.add_variant(DebugMessageTree::new("Child3"));
+		let variants = tree.variants().expect("variants should be Some");
+		assert_eq!(variants.len(), 3);
+		assert_eq!(variants[0].name(), "Child1");
+		assert_eq!(variants[1].name(), "Child2");
+		assert_eq!(variants[2].name(), "Child3");
+	}
+
+	#[test]
+	fn test_add_variant_nested_children() {
+		let mut root = DebugMessageTree::new("Root");
+		let mut child = DebugMessageTree::new("Child");
+		child.add_variant(DebugMessageTree::new("Grandchild"));
+		root.add_variant(child);
+
+		let child_ref = &root.variants().unwrap()[0];
+		let grandchild = &child_ref.variants().unwrap()[0];
+		assert_eq!(grandchild.name(), "Grandchild");
+	}
+
+	//  add_message_handler_field() Tests
+
+	#[test]
+	fn test_add_message_handler_field_sets_value() {
+		let mut tree = DebugMessageTree::new("Node");
+		let msg = sample_message_data();
+		tree.add_message_handler_field(msg);
+		let handler = tree.message_handler_fields().expect("message_handler should be Some");
+		assert_eq!(handler.name(), "TestMessage");
+	}
+
+	#[test]
+	fn test_add_message_handler_field_overwrites() {
+		let mut tree = DebugMessageTree::new("Node");
+		tree.add_message_handler_field(MessageData::new("First".to_string(), vec![], "a.rs", 1));
+		tree.add_message_handler_field(MessageData::new("Second".to_string(), vec![], "b.rs", 2));
+		assert_eq!(tree.message_handler_fields().unwrap().name(), "Second");
+	}
+
+	#[test]
+	fn test_add_message_handler_field_path_and_line() {
+		let mut tree = DebugMessageTree::new("Node");
+		tree.add_message_handler_field(MessageData::new("Handler".to_string(), vec![], "src/handler.rs", 77));
+		let handler = tree.message_handler_fields().unwrap();
+		assert_eq!(handler.path(), "src/handler.rs");
+		assert_eq!(handler.line_number(), 77);
+	}
+
+	//  add_message_handler_data_field() Tests
+
+	#[test]
+	fn test_add_message_handler_data_field_sets_value() {
+		let mut tree = DebugMessageTree::new("Node");
+		let msg = sample_message_data();
+		tree.add_message_handler_data_field(msg);
+		let data = tree.message_handler_data_fields().expect("message_handler_data should be Some");
+		assert_eq!(data.name(), "TestMessage");
+	}
+
+	#[test]
+	fn test_add_message_handler_data_field_overwrites() {
+		let mut tree = DebugMessageTree::new("Node");
+		tree.add_message_handler_data_field(MessageData::new("Old".to_string(), vec![], "x.rs", 5));
+		tree.add_message_handler_data_field(MessageData::new("New".to_string(), vec![], "y.rs", 10));
+		assert_eq!(tree.message_handler_data_fields().unwrap().name(), "New");
+	}
+
+	#[test]
+	fn test_add_message_handler_data_field_stores_fields() {
+		let mut tree = DebugMessageTree::new("Node");
+		tree.add_message_handler_data_field(MessageData::new("DataMsg".to_string(), vec![("x".to_string(), 3), ("y".to_string(), 7)], "src/data.rs", 20));
+		let data = tree.message_handler_data_fields().unwrap();
+		assert_eq!(data.fields(), &vec![("x".to_string(), 3), ("y".to_string(), 7)]);
+	}
+
+	//  Debug format Tests
+
+	#[test]
+	fn test_debug_message_tree_debug_format_contains_name() {
+		let tree = DebugMessageTree::new("DebugMe");
+		let debug_str = format!("{:?}", tree);
+		assert!(debug_str.contains("DebugMe"));
+	}
+}