fix: bound document extraction

src/main/workspace-file-access.test.ts

@@ -0,0 +1,60 @@
+import {
+  mkdtemp,
+  open,
+  rm,
+  writeFile
+} from 'node:fs/promises'
+import { tmpdir } from 'node:os'
+import { join } from 'node:path'
+import { describe, expect, it, vi } from 'vitest'
+import { readBoundedFile } from './workspace-file-access'
+
+type ReadMethod = (
+  this: Awaited<ReturnType<typeof open>>,
+  buffer: Buffer,
+  offset: number,
+  length: number,
+  position: number
+) => Promise<{ bytesRead: number; buffer: Buffer }>
+
+describe('workspace file access', () => {
+  it('continues reading after a short file-handle read', async () => {
+    const directory = await mkdtemp(join(tmpdir(), 'goodbuddy-short-read-'))
+    const path = join(directory, 'short-read.txt')
+    const content = Buffer.from('hello')
+    await writeFile(path, content)
+    const probe = await open(path, 'r')
+    const prototype = Object.getPrototypeOf(probe) as {
+      read: ReadMethod
+    }
+    const originalRead = prototype.read
+    await probe.close()
+    const read = vi
+      .spyOn(prototype, 'read')
+      .mockImplementation(function (
+        this: Awaited<ReturnType<typeof open>>,
+        buffer,
+        offset,
+        length,
+        position
+      ) {
+        return originalRead.call(
+          this,
+          buffer,
+          offset,
+          Math.min(length, position === 0 ? 2 : 3),
+          position
+        )
+      })
+
+    try {
+      await expect(
+        readBoundedFile(path, 5, 'too large')
+      ).resolves.toEqual(content)
+      expect(read).toHaveBeenCalledTimes(3)
+    } finally {
+      read.mockRestore()
+      await rm(directory, { recursive: true, force: true })
+    }
+  })
+})