Refactor site generation into a modular content pipeline

test/dev-reload.test.js

@@ -0,0 +1,53 @@
+import assert from 'node:assert/strict'
+import { test } from 'node:test'
+import { createRegenerationQueue } from '../dev-reload.js'
+
+const waitFor = async (predicate) => {
+  for (let attempt = 0; attempt < 100; attempt += 1) {
+    if (predicate()) return
+    await new Promise((resolve) => setTimeout(resolve, 5))
+  }
+  assert.fail('timed out waiting for generation')
+}
+
+test('rapid edits coalesce and only the latest generation reloads', async () => {
+  const pending = []
+  const events = []
+  const queue = createRegenerationQueue({
+    generate: () => new Promise((resolve) => pending.push(resolve)),
+    onSuccess: () => events.push('reload'),
+    onError: () => events.push('error'),
+    delay: 1,
+  })
+  try {
+    queue.request()
+    queue.request()
+    await waitFor(() => pending.length === 1)
+    queue.request()
+    pending[0]()
+    await waitFor(() => pending.length === 2)
+    assert.deepEqual(events, [])
+    pending[1]()
+    await waitFor(() => events.length === 1)
+    assert.deepEqual(events, ['reload'])
+  } finally {
+    queue.close()
+  }
+})
+
+test('failed latest generation reports an error without reloading', async () => {
+  const events = []
+  const queue = createRegenerationQueue({
+    generate: () => Promise.reject(new Error('broken content')),
+    onSuccess: () => events.push('reload'),
+    onError: (error) => events.push(error.message),
+    delay: 1,
+  })
+  try {
+    queue.request()
+    await waitFor(() => events.length === 1)
+    assert.deepEqual(events, ['broken content'])
+  } finally {
+    queue.close()
+  }
+})