some frontend unit tests

test/frontend/tests/fileSender-tests.js

@@ -0,0 +1,17 @@
+import assert from 'assert';
+import FileSender from '../../../app/fileSender';
+
+// FileSender uses a File in real life but a Blob works for testing
+const blob = new Blob(['hello world!'], { type: 'text/plain' });
+blob.name = 'text.txt';
+
+describe('FileSender', function() {
+  describe('upload', function() {
+    it('returns an OwnedFile on success', async function() {
+      const fs = new FileSender(blob);
+      const file = await fs.upload();
+      assert.ok(file.id);
+      assert.equal(file.name, blob.name);
+    });
+  });
+});