implemented a lot of features

tests/functional/fetch_ranges.spec.ts

@@ -0,0 +1,46 @@
+import { test } from '@japa/runner'
+import db from '@adonisjs/lucid/services/db'
+import testUtils from '@adonisjs/core/services/test_utils'
+import FetchRangeService from '#services/FetchRangeService'
+
+async function groupWithRanges(ranges: [number, number, string][]) {
+  const now = new Date()
+  const [group] = await db
+    .table('groups')
+    .insert({ name: `test.ranges.${Date.now()}`, active: false, last_indexed_id: 100, last_queued_id: 700, created_at: now, updated_at: now })
+    .returning(['id', 'name'])
+  for (const [start, end, status] of ranges) {
+    await db.table('fetch_ranges').insert({ group_id: group.id, start_id: start, end_id: end, status, created_at: now, updated_at: now })
+  }
+  return { id: Number(group.id), name: group.name }
+}
+
+test.group('FetchRangeService.advanceWatermark', (group) => {
+  group.each.setup(() => testUtils.db().withGlobalTransaction())
+
+  test('stops just below the first range that is not done', async ({ assert }) => {
+    const g = await groupWithRanges([
+      [101, 200, 'done'],
+      [201, 300, 'failed'],
+      [301, 400, 'done'],
+      [401, 700, 'queued'],
+    ])
+    assert.equal(await FetchRangeService.advanceWatermark(g), 200n)
+    // done ranges are forgotten, the gap and the queued range stay
+    const left = await db.from('fetch_ranges').where('group_id', g.id).orderBy('start_id').select('status')
+    assert.deepEqual(left.map((r) => r.status), ['failed', 'queued'])
+  })
+
+  test('reaches the queue cursor when everything is done', async ({ assert }) => {
+    const g = await groupWithRanges([
+      [101, 400, 'done'],
+      [401, 700, 'done'],
+    ])
+    assert.equal(await FetchRangeService.advanceWatermark(g), 700n)
+  })
+
+  test('never moves backwards', async ({ assert }) => {
+    const g = await groupWithRanges([[50, 60, 'failed']])
+    assert.equal(await FetchRangeService.advanceWatermark(g), 100n)
+  })
+})