Add `UserView` tests

test/userview_test.dart

@@ -0,0 +1,53 @@
+import 'dart:convert';
+
+import 'package:flutter_test/flutter_test.dart';
+import 'package:lemmur/client/models/user.dart';
+
+void main() {
+  test("UserView test", () {
+    Map<String, dynamic> userJson = jsonDecode("""
+      {
+        "id": 13709,
+        "actor_id": "https://dev.lemmy.ml/u/krawieck",
+        "name": "krawieck",
+        "preferred_username": null,
+        "avatar": null,
+        "banner": null,
+        "email": null,
+        "matrix_user_id": null,
+        "bio": null,
+        "local": true,
+        "admin": false,
+        "banned": false,
+        "show_avatars": true,
+        "send_notifications_to_email": false,
+        "published": "2020-08-03T12:22:12.389085",
+        "number_of_posts": 0,
+        "post_score": 0,
+        "number_of_comments": 0,
+        "comment_score": 0
+      }""");
+
+    var user = UserView.fromJson(userJson);
+
+    expect(user.id, 13709);
+    expect(user.actorId, "https://dev.lemmy.ml/u/krawieck");
+    expect(user.name, "krawieck");
+    expect(user.preferredUsername, null);
+    expect(user.avatar, null);
+    expect(user.banner, null);
+    expect(user.email, null);
+    expect(user.matrixUserId, null);
+    expect(user.bio, null);
+    expect(user.local, true);
+    expect(user.admin, false);
+    expect(user.banned, false);
+    expect(user.showAvatars, true);
+    expect(user.sendNotificationsToEmail, false);
+    expect(user.published, DateTime.parse("2020-08-03T12:22:12.389085"));
+    expect(user.numberOfPosts, 0);
+    expect(user.postScore, 0);
+    expect(user.numberOfComments, 0);
+    expect(user.commentScore, 0);
+  });
+}