1 files changed, 18 insertions, 0 deletions
diff --git a/packages/todo/src/format.test.ts b/packages/todo/src/format.test.ts
new file mode 100644
index 0000000..bffb8a3
--- /dev/null
+++ b/packages/todo/src/format.test.ts
@@ -0,0 +1,18 @@
+import { describe, expect, it } from "vitest";
+import { formatTodoResult, type TodoItem } from "./pure.js";
+
+describe("formatTodoResult", () => {
+	it("formatTodoResult: returns JSON string of the todos", () => {
+		const todos: TodoItem[] = [
+			{ content: "alpha", status: "in_progress" },
+			{ content: "beta", status: "pending" },
+		];
+		expect(formatTodoResult(todos)).toBe(JSON.stringify(todos, null, 2));
+		// spot-check it is pretty-printed JSON (indented key)
+		expect(formatTodoResult(todos)).toContain('"content": "alpha"');
+	});
+
+	it('formatTodoResult: empty array returns "[]"', () => {
+		expect(formatTodoResult([])).toBe("[]");
+	});
+});