1 files changed, 66 insertions, 0 deletions
diff --git a/packages/todo/src/validate.test.ts b/packages/todo/src/validate.test.ts
new file mode 100644
index 0000000..c518041
--- /dev/null
+++ b/packages/todo/src/validate.test.ts
@@ -0,0 +1,66 @@
+import { describe, expect, it } from "vitest";
+import { validateTodos } from "./pure.js";
+
+describe("validateTodos", () => {
+	it("validateTodos: accepts valid list", () => {
+		const result = validateTodos({
+			todos: [
+				{ content: "Do thing A", status: "pending" },
+				{ content: "Do thing B", status: "in_progress" },
+				{ content: "Do thing C", status: "completed" },
+			],
+		});
+		expect(result).toEqual([
+			{ content: "Do thing A", status: "pending" },
+			{ content: "Do thing B", status: "in_progress" },
+			{ content: "Do thing C", status: "completed" },
+		]);
+	});
+
+	it("validateTodos: accepts empty array (clears the list)", () => {
+		const result = validateTodos({ todos: [] });
+		expect(result).toEqual([]);
+	});
+
+	it("validateTodos: rejects invalid status", () => {
+		const result = validateTodos({
+			todos: [{ content: "x", status: "bogus" }],
+		});
+		expect(result).toHaveProperty("error");
+	});
+
+	it("validateTodos: rejects empty content", () => {
+		const empty = validateTodos({
+			todos: [{ content: "", status: "pending" }],
+		});
+		expect(empty).toHaveProperty("error");
+		const whitespace = validateTodos({
+			todos: [{ content: "   ", status: "pending" }],
+		});
+		expect(whitespace).toHaveProperty("error");
+	});
+
+	it("validateTodos: rejects non-array todos", () => {
+		const result = validateTodos({ todos: "not-an-array" });
+		expect(result).toHaveProperty("error");
+	});
+
+	it("validateTodos: rejects null/non-object args", () => {
+		expect(validateTodos(null)).toHaveProperty("error");
+		expect(validateTodos(undefined)).toHaveProperty("error");
+		expect(validateTodos("string")).toHaveProperty("error");
+		expect(validateTodos(42)).toHaveProperty("error");
+		expect(validateTodos([])).toHaveProperty("error");
+	});
+
+	it("validateTodos: does NOT enforce one in_progress (allows multiple — description guides the model)", () => {
+		const result = validateTodos({
+			todos: [
+				{ content: "a", status: "in_progress" },
+				{ content: "b", status: "in_progress" },
+			],
+		});
+		expect(Array.isArray(result)).toBe(true);
+		expect(result).toHaveLength(2);
+	});
+});