test: cover save slot quota overflow

spec/createEffectsHandler.storage.test.js

@@ -0,0 +1,81 @@
+import { afterEach, describe, expect, it, vi } from "vitest";
+import createEffectsHandler from "../src/createEffectsHandler.js";
+
+const createTicker = () => ({
+  add: vi.fn(),
+  remove: vi.fn(),
+});
+
+const createEngine = () => ({
+  selectRenderState: vi.fn(() => ({ id: "render-1" })),
+  handleAction: vi.fn(),
+  handleActions: vi.fn(),
+  handleInternalAction: vi.fn(),
+});
+
+describe("createEffectsHandler storage effects", () => {
+  afterEach(() => {
+    vi.restoreAllMocks();
+    vi.unstubAllGlobals();
+  });
+
+  it("throws when localStorage quota is exceeded while saving saveSlots", () => {
+    const quotaExceededError = new Error("quota exceeded");
+    quotaExceededError.name = "QuotaExceededError";
+
+    const setItem = vi.fn().mockImplementation(() => {
+      throw quotaExceededError;
+    });
+
+    vi.stubGlobal("localStorage", {
+      setItem,
+    });
+
+    const routeGraphics = {
+      render: vi.fn(),
+    };
+
+    const effectsHandler = createEffectsHandler({
+      getEngine: createEngine,
+      routeGraphics,
+      ticker: createTicker(),
+    });
+
+    const saveSlots = {
+      1: {
+        formatVersion: 1,
+        slotId: 1,
+        savedAt: 1700000000000,
+        image: "data:image/jpeg;base64,thumbnail",
+        state: {
+          contexts: [{ id: "context-1" }],
+          viewedRegistry: {
+            sections: [],
+            resources: [],
+          },
+        },
+      },
+    };
+
+    expect(() => {
+      effectsHandler([
+        {
+          name: "saveSlots",
+          payload: {
+            saveSlots,
+          },
+        },
+        {
+          name: "render",
+        },
+      ]);
+    }).toThrow(quotaExceededError);
+
+    expect(setItem).toHaveBeenCalledTimes(1);
+    expect(setItem).toHaveBeenCalledWith(
+      "saveSlots",
+      JSON.stringify(saveSlots),
+    );
+    expect(routeGraphics.render).not.toHaveBeenCalled();
+  });
+});