vault-link/frontend/sync-client/src/services/fetch-controller.test.ts

import { describe, it, mock, beforeEach, afterEach } from "node:test";
import assert from "node:assert";
import { FetchController } from "./fetch-controller";
import { Logger } from "../tracing/logger";
import { SyncResetError } from "./sync-reset-error";
import { sleep } from "../utils/sleep";

describe("FetchController", () => {
	const createMockFetch = (shouldSleep: boolean) =>
		mock.fn(async () => {
			if (shouldSleep) {
				await sleep(30);
			}
			return Promise.resolve(new Response("OK", { status: 200 }));
		});

	beforeEach(() => {
		mock.timers.enable({ apis: ["setTimeout"] });
	});

	afterEach(() => {
		mock.timers.reset();
	});

	it("should allow fetch when canFetch is true", async () => {
		const logger = new Logger();
		const controller = new FetchController(true, logger);
		const mockFetch = createMockFetch(false);
		const controlledFetch = controller.getControlledFetchImplementation(
			logger,
			mockFetch
		);

		const response = await controlledFetch("http://example.com");

		assert.strictEqual(await response.text(), "OK");
		assert.strictEqual(mockFetch.mock.calls.length, 1);
	});

	it("should block fetch until canFetch becomes true", async () => {
		const logger = new Logger();
		const controller = new FetchController(false, logger);
		const mockFetch = createMockFetch(true);
		const controlledFetch = controller.getControlledFetchImplementation(
			logger,
			mockFetch
		);

		const fetchPromise = controlledFetch("http://example.com");
		assert.strictEqual(mockFetch.mock.calls.length, 0);

		controller.canFetch = true;
		await Promise.resolve();
		mock.timers.tick(30);

		const response = await fetchPromise;
		assert.strictEqual(await response.text(), "OK");
		assert.strictEqual(mockFetch.mock.calls.length, 1);
	});

	it("should reject during reset", async () => {
		const logger = new Logger();
		const controller = new FetchController(true, logger);
		const mockFetch = createMockFetch(true);
		const controlledFetch = controller.getControlledFetchImplementation(
			logger,
			mockFetch
		);

		const firstRequest = controlledFetch("http://example.com");
		assert.strictEqual(mockFetch.mock.calls.length, 1);

		controller.startReset();

		const secondRequest = controlledFetch("http://example.com");

		await assert.rejects(
			firstRequest,
			(error: unknown) => error instanceof SyncResetError
		);
		await assert.rejects(
			secondRequest,
			(error: unknown) => error instanceof SyncResetError
		);
		assert.strictEqual(mockFetch.mock.calls.length, 1);
	});

	it("should allow fetch after reset finishes", async () => {
		const logger = new Logger();
		const controller = new FetchController(true, logger);
		const mockFetch = createMockFetch(false);
		const controlledFetch = controller.getControlledFetchImplementation(
			logger,
			mockFetch
		);

		controller.startReset();
		controller.finishReset();

		const response = await controlledFetch("http://example.com");
		assert.strictEqual(await response.text(), "OK");
	});

	it("should throw when finishing reset without starting", () => {
		const logger = new Logger();
		const controller = new FetchController(true, logger);

		assert.throws(
			() => controller.finishReset(),
			(error: unknown) =>
				error instanceof Error &&
				error.message === "Cannot finish reset when not resetting"
		);
	});

	it("should defer canFetch changes during reset", async () => {
		const logger = new Logger();
		const controller = new FetchController(false, logger);
		const mockFetch = createMockFetch(true);
		const controlledFetch = controller.getControlledFetchImplementation(
			logger,
			mockFetch
		);

		controller.startReset();
		controller.canFetch = true;

		await assert.rejects(
			async () => controlledFetch("http://example.com"),
			(error: unknown) => error instanceof SyncResetError
		);

		controller.finishReset();

		const fetchPromise = controlledFetch("http://example.com");
		mock.timers.tick(30);

		const response = await fetchPromise;
		assert.strictEqual(await response.text(), "OK");
	});

	it("should handle different input types", async () => {
		const logger = new Logger();
		const controller = new FetchController(true, logger);
		const mockFetch = createMockFetch(false);
		const controlledFetch = controller.getControlledFetchImplementation(
			logger,
			mockFetch
		);

		await controlledFetch("http://example.com");
		await controlledFetch(new URL("http://example.com"));
		await controlledFetch(
			new Request("http://example.com", { method: "POST" })
		);

		assert.strictEqual(mockFetch.mock.calls.length, 3);
	});

	it("should handle fetch errors", async () => {
		const logger = new Logger();
		const controller = new FetchController(true, logger);
		const mockFetch = mock.fn(async () => {
			throw new Error("Network error");
		});
		const controlledFetch = controller.getControlledFetchImplementation(
			logger,
			mockFetch
		);

		await assert.rejects(
			async () => controlledFetch("http://example.com"),
			(error: unknown) =>
				error instanceof Error && error.message === "Network error"
		);
	});

	it("should not create unhandled rejection on reset with no waiting fetches", async () => {
		const logger = new Logger();
		const controller = new FetchController(true, logger);

		controller.startReset();
		mock.timers.tick(10);
		controller.finishReset();
	});
});