diff --git a/packages/runtime/test/modal-handler.test.ts b/packages/runtime/test/modal-handler.test.ts
new file mode 100644
index 0000000..0f1c529
--- /dev/null
+++ b/packages/runtime/test/modal-handler.test.ts
@@ -0,0 +1,146 @@
+import { beforeEach, describe, expect, mock, test } from "bun:test";
+import { Client } from "discord.js";
+import ModalHandler from "../handler/ModalHandler";
+import Modal from "../interaction/Modal";
+
+describe("ModalHandler", () => {
+	let client: Client;
+	let handler: ModalHandler;
+
+	beforeEach(() => {
+		process.env.NODE_ENV = "test"; // Use in-memory DB
+		client = new Client({ intents: [] });
+		handler = new ModalHandler(client);
+	});
+
+	describe("registration", () => {
+		test("should add a modal", async () => {
+			const modal = new Modal().setCustomId("test-modal").run(() => {});
+			handler.add(modal);
+			// Verify it was added by triggering it with a fake interaction
+			const executed = mock(() => {});
+			modal.run(executed);
+
+			const interaction = {
+				customId: "test-modal",
+			} as any;
+
+			await handler.onModalSubmit(interaction);
+			expect(executed).toHaveBeenCalled();
+		});
+
+		test("should set multiple modals", async () => {
+			const modal1 = new Modal().setCustomId("test-modal-1").run(() => {});
+			const modal2 = new Modal().setCustomId("test-modal-2").run(() => {});
+
+			handler.set([modal1, modal2]);
+
+			const executed1 = mock(() => {});
+			const executed2 = mock(() => {});
+			modal1.run(executed1);
+			modal2.run(executed2);
+
+			await handler.onModalSubmit({ customId: "test-modal-1" } as any);
+			await handler.onModalSubmit({ customId: "test-modal-2" } as any);
+
+			expect(executed1).toHaveBeenCalled();
+			expect(executed2).toHaveBeenCalled();
+		});
+
+		test("should delete a modal", async () => {
+			const modal = new Modal().setCustomId("test-modal").run(() => {});
+			handler.add(modal);
+			handler.delete("test-modal");
+
+			const executed = mock(() => {});
+			modal.run(executed);
+
+			const interaction = {
+				customId: "test-modal",
+			} as any;
+
+			await handler.onModalSubmit(interaction);
+			expect(executed).not.toHaveBeenCalled();
+		});
+	});
+
+	describe("interaction routing", () => {
+		test("should route modal interaction without data", async () => {
+			const executed = mock(() => {});
+			const modal = new Modal().setCustomId("test-modal").run(executed);
+
+			handler.add(modal);
+
+			const interaction = {
+				customId: "test-modal",
+			} as any;
+
+			await handler.onModalSubmit(interaction);
+			expect(executed).toHaveBeenCalled();
+		});
+
+		test("should route modal interaction with data", async () => {
+			const executed = mock((_, data) => {
+				expect(data).toEqual({ id: 1 });
+			});
+			const modal = new Modal<{ id: number }>()
+				.setCustomId("data-modal")
+				.run(executed);
+
+			handler.add(modal);
+
+			const { InteractionHelper } = await import("../interaction/BaseInteraction");
+			const token = InteractionHelper.storeData({ id: 1 });
+			const interaction = {
+				customId: `data-modal:${token}`,
+			} as any;
+
+			await handler.onModalSubmit(interaction);
+			expect(executed).toHaveBeenCalled();
+		});
+
+		test("should handle expired interaction data", async () => {
+			const modal = new Modal().setCustomId("expired-modal").run(() => {});
+			handler.add(modal);
+
+			const reply = mock(() => {});
+			const interaction = {
+				customId: "expired-modal:invalid",
+				reply,
+			} as any;
+
+			await handler.onModalSubmit(interaction);
+			expect(reply).toHaveBeenCalled();
+		});
+	});
+
+	describe("error handling", () => {
+		test("should handle errors during execution", async () => {
+			const originalConsoleError = console.error;
+			console.error = mock(() => {}); // suppress expected error log
+
+			const modal = new Modal()
+				.setCustomId("error-modal")
+				.run(() => {
+					throw new Error("Test error");
+				});
+			handler.add(modal);
+
+			const reply = mock(() => {});
+			const interaction = {
+				customId: "error-modal",
+				reply,
+				isRepliable: () => true,
+				replied: false,
+				deferred: false,
+			} as any;
+
+			await handler.onModalSubmit(interaction);
+
+			expect(reply).toHaveBeenCalled();
+			expect(console.error).toHaveBeenCalled();
+
+			console.error = originalConsoleError;
+		});
+	});
+});