add test to check that docs refer to existing attachments in zip

package.json

@@ -27,6 +27,7 @@
     "eslint": "^9.15.0",
     "globals": "^15.12.0",
     "npm-run-all": "^4.1.5",
+    "mime": "^4.0.4",
     "patch-package": "^8.0.0",
     "prettier": "^3.3.3",
     "typescript": "^5.6.3",

test/writer.js

@@ -1,11 +1,16 @@
 import test from "node:test";
-import { join, relative } from 'node:path'
+import { join, relative, basename } from 'node:path'
 import { json } from 'node:stream/consumers';
 import fs from 'node:fs/promises'
 import assert from "node:assert/strict";
 import yauzl from 'yauzl-promise'
+import mime from 'mime/lite';
 import MLEFWriter from "../src/writer.js";
 
+// add testing of links of docs to attachments
+// 1. if there's a ref, check that file exists (on the three folders?)
+// 2. check that there is no image unreferenced? (not that important)
+
 test("loading and packing a db into a zip", async (t) => {
   const dbName = 'db1'
   const path = new URL(join('./fixture', dbName), import.meta.url).pathname;
@@ -55,6 +60,17 @@ test("loading and packing a db into a zip", async (t) => {
     'the docs zipped matches the original'
   )
 
+  const attachmentsRef = docsInZip.flatMap(doc => doc.attachments)
+  const attachmentsInZipAsRefs = attachmentsInZip
+  .filter(attachment => attachment.match(/original/))
+  .map(attachment => ({ id: basename(attachment), type: mime.getType(attachment) }))
+
+  assert.deepEqual(
+    new Set(attachmentsRef),
+    new Set(attachmentsInZipAsRefs),
+    'references to attachments in docs link to images that exist'
+  )
+
   t.after(async () => {
     await teardown([out, outDefaultPath])
     zip.close()