explorer: add tests for +page.svelte routes

explorer/src/routes/blocks/__tests__/page.spec.js

@@ -0,0 +1,58 @@
+import { afterAll, afterEach, describe, expect, it, vi } from "vitest";
+import { cleanup, render } from "@testing-library/svelte";
+import { get } from "svelte/store";
+
+import { duskAPI } from "$lib/services";
+import { transformBlock } from "$lib/chain-info";
+import { appStore } from "$lib/stores";
+import { apiBlocks } from "$lib/mock-data";
+
+import Blocks from "../+page.svelte";
+
+describe("Blocks page", () => {
+  vi.useFakeTimers();
+
+  const { fetchInterval, network } = get(appStore);
+  const getBlocksSpy = vi
+    .spyOn(duskAPI, "getBlocks")
+    .mockResolvedValue(apiBlocks.data.blocks.map(transformBlock));
+
+  afterEach(() => {
+    cleanup();
+    getBlocksSpy.mockClear();
+  });
+
+  afterAll(() => {
+    vi.useRealTimers();
+    getBlocksSpy.mockRestore();
+  });
+
+  it("should render the Blocks page, start polling for blocks and stop the polling when unmounted", async () => {
+    const { container, unmount } = render(Blocks);
+
+    expect(container.firstChild).toMatchSnapshot();
+    expect(getBlocksSpy).toHaveBeenCalledTimes(1);
+    expect(getBlocksSpy).toHaveBeenNthCalledWith(1, network);
+
+    await vi.advanceTimersByTimeAsync(1);
+
+    // snapshot with received data from APIs
+    expect(container.firstChild).toMatchSnapshot();
+
+    await vi.advanceTimersByTimeAsync(fetchInterval - 1);
+
+    expect(getBlocksSpy).toHaveBeenCalledTimes(2);
+    expect(getBlocksSpy).toHaveBeenNthCalledWith(2, network);
+
+    await vi.advanceTimersByTimeAsync(fetchInterval);
+
+    expect(getBlocksSpy).toHaveBeenCalledTimes(3);
+    expect(getBlocksSpy).toHaveBeenNthCalledWith(3, network);
+
+    unmount();
+
+    await vi.advanceTimersByTimeAsync(fetchInterval * 10);
+
+    expect(getBlocksSpy).toHaveBeenCalledTimes(3);
+  });
+});