Add tests for DebouncedCache

assets/js/utils/__tests__/debounced-cache.spec.ts

@@ -0,0 +1,150 @@
+import { DebouncedCache } from '../debounced-cache';
+
+describe('DebouncedCache', () => {
+  beforeAll(() => {
+    vi.useFakeTimers();
+  });
+
+  const consoleSpy = {
+    debug: vi.spyOn(console, 'debug'),
+    error: vi.spyOn(console, 'error'),
+  };
+
+  afterEach(() => {
+    consoleSpy.debug.mockClear();
+    consoleSpy.error.mockClear();
+  });
+
+  it('should call the function after a debounce threshold and cache the result', async () => {
+    const { producer, cache } = createTestCache();
+
+    const consumer = vi.fn();
+
+    cache.schedule({ a: 1, b: 2 }, consumer);
+    await vi.runAllTimersAsync();
+
+    expect(producer).toHaveBeenCalledWith({ a: 1, b: 2 });
+    expect(consumer).toHaveBeenCalledWith(3);
+
+    cache.schedule({ a: 1, b: 2 }, consumer);
+    await vi.runAllTimersAsync();
+
+    expect(producer).toHaveBeenCalledTimes(1);
+    expect(consumer).toHaveBeenCalledTimes(2);
+
+    expect(consoleSpy.debug).not.toHaveBeenCalled();
+    expect(consoleSpy.error).not.toHaveBeenCalled();
+  });
+
+  describe('should abort the last scheduled call when a new one is scheduled', () => {
+    test('scheduling before the debounce threshold is reached', async () => {
+      const { producer, cache } = createTestCache();
+
+      const consumer1 = vi.fn();
+      const consumer2 = vi.fn();
+
+      cache.schedule({ a: 1, b: 2 }, consumer1);
+      cache.schedule({ a: 1, b: 2 }, consumer2);
+      await vi.runAllTimersAsync();
+
+      expect(consumer1).not.toHaveBeenCalled();
+      expect(consumer2).toHaveBeenCalledWith(3);
+      expect(producer).toHaveBeenCalledOnce();
+
+      // No logs should be emitted because the `setTimeout` call itself should have been aborted.
+      expect(consoleSpy.debug.mock.calls).toMatchInlineSnapshot(`[]`);
+      expect(consoleSpy.error.mock.calls).toMatchInlineSnapshot(`[]`);
+    });
+
+    test('scheduling after the debounce threshold is reached', async () => {
+      const threshold = 300;
+      const { producer, cache } = createTestCache(threshold);
+
+      const consumer1 = vi.fn();
+      const consumer2 = vi.fn();
+
+      cache.schedule({ a: 1, b: 2 }, consumer1);
+      vi.advanceTimersByTime(threshold);
+
+      cache.schedule({ a: 1, b: 2 }, consumer2);
+      await vi.runAllTimersAsync();
+
+      expect(consumer1).not.toHaveBeenCalled();
+      expect(consumer2).toHaveBeenCalledWith(3);
+      expect(producer).toHaveBeenCalledOnce();
+
+      expect(consoleSpy.debug.mock.calls).toMatchInlineSnapshot(`
+        [
+          [
+            "A call was aborted after the debounce threshold was reached",
+            DOMException {},
+          ],
+        ]
+      `);
+      expect(consoleSpy.error.mock.calls).toMatchInlineSnapshot(`[]`);
+    });
+  });
+
+  describe('should handle errors by logging them', () => {
+    test('error in producer', async () => {
+      const producer = vi.fn(() => Promise.reject(new Error('producer error')));
+      const cache = new DebouncedCache(producer);
+
+      const consumer = vi.fn();
+
+      cache.schedule(undefined, consumer);
+      await vi.runAllTimersAsync();
+
+      expect(consumer).not.toHaveBeenCalled();
+
+      expect(consoleSpy.debug).not.toHaveBeenCalled();
+      expect(consoleSpy.error.mock.calls).toMatchInlineSnapshot(`
+        [
+          [
+            "An error occurred while calling 'spy'.",
+            [Error: producer error],
+          ],
+        ]
+      `);
+    });
+
+    test('error in consumer', async () => {
+      const { producer, cache } = createTestCache();
+
+      const consumer = vi.fn(() => {
+        throw new Error('consumer error');
+      });
+
+      cache.schedule({ a: 1, b: 2 }, consumer);
+      await vi.runAllTimersAsync();
+
+      expect(producer).toHaveBeenCalledOnce();
+
+      expect(consoleSpy.debug).not.toHaveBeenCalled();
+      expect(consoleSpy.error.mock.calls).toMatchInlineSnapshot(`
+          [
+            [
+              "An error occurred while processing the result of 'producerImpl'.",
+              [Error: consumer error],
+            ],
+          ]
+        `);
+    });
+  });
+});
+
+function createTestCache(thresholdMs?: number) {
+  const producer = vi.fn(producerImpl);
+  const cache = new DebouncedCache(producer, { thresholdMs });
+
+  return { producer, cache };
+}
+
+interface ProducerParams {
+  a: number;
+  b: number;
+}
+
+async function producerImpl(params: ProducerParams): Promise<number> {
+  return params.a + params.b;
+}