feat: add files package

packages/files/src/Domain/UseCase/FileDownloader.spec.ts

@@ -0,0 +1,58 @@
+import { FileContent } from '@standardnotes/models'
+import { FilesApiInterface } from '@standardnotes/services'
+import { FileDownloader } from './FileDownloader'
+
+describe('file downloader', () => {
+  let apiService: FilesApiInterface
+  let downloader: FileDownloader
+  let file: {
+    encryptedChunkSizes: FileContent['encryptedChunkSizes']
+    remoteIdentifier: FileContent['remoteIdentifier']
+  }
+
+  const numChunks = 5
+
+  beforeEach(() => {
+    apiService = {} as jest.Mocked<FilesApiInterface>
+    apiService.createFileValetToken = jest.fn()
+    apiService.downloadFile = jest
+      .fn()
+      .mockImplementation(
+        (
+          _file: string,
+          _chunkIndex: number,
+          _apiToken: string,
+          _rangeStart: number,
+          onBytesReceived: (bytes: Uint8Array) => void,
+        ) => {
+          return new Promise<void>((resolve) => {
+            for (let i = 0; i < numChunks; i++) {
+              onBytesReceived(Uint8Array.from([0xaa]))
+            }
+
+            resolve()
+          })
+        },
+      )
+
+    file = {
+      encryptedChunkSizes: [100_000],
+      remoteIdentifier: '123',
+    }
+  })
+
+  it('should pass back bytes as they are received', async () => {
+    let receivedBytes = new Uint8Array()
+
+    downloader = new FileDownloader(file, apiService)
+
+    expect(receivedBytes.length).toBe(0)
+
+    // eslint-disable-next-line @typescript-eslint/require-await
+    await downloader.run(async (encryptedBytes) => {
+      receivedBytes = new Uint8Array([...receivedBytes, ...encryptedBytes])
+    })
+
+    expect(receivedBytes.length).toEqual(numChunks)
+  })
+})