test: add test for state helper

packages/hono-do/tests/helper/state.test.ts

@@ -0,0 +1,81 @@
+import { Updater, defineState } from "../../src/helper/state";
+
+describe("defineState", () => {
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  let storage: any;
+
+  beforeEach(() => {
+    storage = {
+      get: vi.fn(),
+      put: vi.fn(),
+    };
+  });
+
+  afterEach(() => {
+    vi.resetAllMocks();
+  });
+
+  it("set infered type correctly", async () => {
+    const [get, set] = await defineState(storage, "key", "value");
+
+    expectTypeOf(get).toEqualTypeOf<() => Promise<string>>();
+    expectTypeOf(set).toEqualTypeOf<
+      (value: string | Updater<string>) => Promise<string>
+    >();
+  });
+
+  it("set complex type correctly", async () => {
+    type ComplexType =
+      | {
+          status: "success";
+          data: {
+            foo: string;
+            bar: number;
+          };
+        }
+      | {
+          status: "error";
+          message: string;
+        };
+
+    const [get, set] = await defineState<ComplexType>(storage, "key", {
+      status: "success",
+      data: {
+        foo: "foo",
+        bar: 1,
+      },
+    });
+
+    expectTypeOf(get).toEqualTypeOf<() => Promise<ComplexType>>();
+    expectTypeOf(set).toEqualTypeOf<
+      (value: ComplexType | Updater<ComplexType>) => Promise<ComplexType>
+    >();
+
+    await set({
+      status: "error",
+      message: "error",
+    });
+  });
+
+  it("should work geter", async () => {
+    const [get] = await defineState(storage, "key", "value");
+
+    expect(await get()).toBe("value");
+    expect(storage.get).toBeCalledWith("key");
+    expect(storage.put).toBeCalledWith("key", "value");
+  });
+
+  it("should work setter (value)", async () => {
+    const [_, set] = await defineState(storage, "key", "value");
+
+    await set("new value");
+    expect(storage.put).toBeCalledWith("key", "new value");
+  });
+
+  it("should work setter (updater)", async () => {
+    const [_, set] = await defineState(storage, "key", "value");
+
+    await set((prev) => `${prev} + ${prev}`);
+    expect(storage.put).toBeCalledWith("key", "value + value");
+  });
+});