add e2e testing (#167)

Reviewed-on: #167

integration_test/links_test.dart

@@ -0,0 +1,56 @@
+import "package:flutter_test/flutter_test.dart";
+import "package:integration_test/integration_test.dart";
+import "package:nexus/widgets/room_chat/room_chat.dart";
+import "package:nexus/widgets/rooms/room_summary_sheet.dart";
+import "package:nexus/widgets/users/user_bottom_sheet.dart";
+
+import "helpers/matrix_user.dart";
+import "helpers/test_app.dart";
+import "helpers/pump_until.dart";
+
+void main() {
+  IntegrationTestWidgetsFlutterBinding.ensureInitialized();
+
+  final app = TestApp("dave", "davepass");
+  setUpAll(app.setUp);
+  final run = DateTime.now().millisecondsSinceEpoch;
+  Future<MatrixUser> bob() => MatrixUser.login("bob", "bobpass");
+
+  Future<void> openLink(WidgetTester tester, String link) async {
+    await app.open(tester);
+    app.fakes.links.open(.parse(link));
+  }
+
+  group("a link opened by the OS", () {
+    testWidgets("to a user opens their popover", (tester) async {
+      await openLink(tester, "matrix:u/bob:localhost");
+
+      await tester.pumpUntil(find.byType(UserBottomSheet));
+    });
+
+    testWidgets("to a joined room opens it", (tester) async {
+      final inviter = await bob();
+      final roomId = await inviter.createRoom("Linked $run");
+      // Joined before Nexus starts, so the room is there once it syncs
+      await app.join(inviter, roomId);
+
+      await openLink(tester, "matrix:roomid/${roomId.substring(1)}");
+
+      await tester.pumpUntil(
+        find.byWidgetPredicate(
+          (widget) => widget is RoomChat && widget.roomId == roomId,
+        ),
+      );
+    });
+
+    testWidgets("to a room that isn't joined shows its summary", (
+      tester,
+    ) async {
+      final roomId = await (await bob()).createRoom("Unjoined $run");
+
+      await openLink(tester, "matrix:roomid/${roomId.substring(1)}");
+
+      await tester.pumpUntil(find.byType(RoomSummarySheet));
+    });
+  });
+}