feat(snjs): add e2e test for subsequent subscriptions settings persistance

packages/snjs/mocha/lib/Files.js

@@ -0,0 +1,31 @@
+export async function uploadFile(fileService, buffer, name, ext, chunkSize) {
+  const operation = await fileService.beginNewFileUpload(buffer.byteLength)
+
+  let chunkId = 1
+  for (let i = 0; i < buffer.length; i += chunkSize) {
+    const readUntil = i + chunkSize > buffer.length ? buffer.length : i + chunkSize
+    const chunk = buffer.slice(i, readUntil)
+    const isFinalChunk = readUntil === buffer.length
+
+    const error = await fileService.pushBytesForUpload(operation, chunk, chunkId++, isFinalChunk)
+    if (error) {
+      throw new Error('Could not upload file chunk')
+    }
+  }
+
+  const file = await fileService.finishUpload(operation, name, ext)
+
+  return file
+}
+
+export async function downloadFile(fileService, itemManager, remoteIdentifier) {
+  const file = itemManager.getItems(ContentType.File).find((file) => file.remoteIdentifier === remoteIdentifier)
+
+  let receivedBytes = new Uint8Array()
+
+  await fileService.downloadFile(file, (decryptedBytes) => {
+    receivedBytes = new Uint8Array([...receivedBytes, ...decryptedBytes])
+  })
+
+  return receivedBytes
+}