test: add a basic test for file change queue

src/createFileChangeQueue.test.ts

@@ -0,0 +1,70 @@
+import { createFileChangeQueue } from './createFileChangeQueue';
+import { type Subscription } from './types';
+import { mkdir, rmdir, writeFile } from 'node:fs/promises';
+import { join } from 'node:path';
+import { setTimeout } from 'node:timers/promises';
+import * as sinon from 'sinon';
+import { beforeEach, expect, test } from 'vitest';
+
+const FIXTURES_DIRECTORY = join(__dirname, '.createFileChangeQueueFixtures');
+
+beforeEach(async () => {
+  try {
+    await rmdir(FIXTURES_DIRECTORY, {
+      recursive: true,
+    });
+  } catch {
+    //
+  }
+
+  await mkdir(FIXTURES_DIRECTORY);
+});
+
+test('deduplicates triggers', async () => {
+  const fooFile = join(FIXTURES_DIRECTORY, 'foo');
+
+  await writeFile(fooFile, 'foo');
+
+  const abortController = new AbortController();
+
+  const trigger = sinon.stub().resolves(null);
+
+  const subscription: Subscription = {
+    activeTask: null,
+    expression: ['match', '*'],
+    initialRun: false,
+    persistent: false,
+    teardown: async () => {},
+    trigger,
+  };
+
+  const fileChangeQueue = createFileChangeQueue({
+    abortSignal: abortController.signal,
+    project: FIXTURES_DIRECTORY,
+    subscriptions: [subscription],
+    userDebounce: {
+      wait: 100,
+    },
+  });
+
+  fileChangeQueue.trigger({
+    filename: fooFile,
+    hash: 'bar',
+  });
+
+  fileChangeQueue.trigger({
+    filename: fooFile,
+    hash: 'baz',
+  });
+
+  await setTimeout(200);
+
+  expect(trigger.callCount).toBe(1);
+
+  expect(trigger.firstCall.args[0]).toEqual([
+    {
+      filename: fooFile,
+      hash: 'baz',
+    },
+  ]);
+});