flutter - How to make widget testing while using http.post

Question

I'm trying to use widget test for my project and test works fine till reach the point I use an http request in the actual page and it ,I think, ignore the request

final account = await http.post(
                  'http://10.0.2.2:5000/LogIn',
                  headers: <String, String>{
                    'Content-Type': 'application/json; charset=UTF-8',
                  },
                  body: json.encode({'email': email, 'password': password}),
                );

the account.body returns empty while it works well during using the emulator

 testWidgets("Successful Sign In", (WidgetTester tester) async {
  await tester.pumpWidget(MaterialApp(home: SignIn()));

  //1-find widgets needed
  final textfieldemail = find.byKey(Key("emailtextformfield"));
  expect(textfieldemail, findsOneWidget);
  final textfieldpassword = find.byKey(Key("passwordtextformfield"));
  expect(textfieldpassword, findsOneWidget);
  final buttonsignin = find.byKey(Key("Signin"));
  expect(buttonsignin, findsOneWidget);

  //2-execute the actual test
  await tester.enterText(textfieldemail, "[email protected]");
  await tester.enterText(textfieldpassword, "Weaam@91");
  await tester.tap(buttonsignin);
  await tester.pump(Duration(seconds: 5));
  //await tester.pump(Duration(seconds: 5));
  //await _navigateToAccountHome(tester);

  //3-check results
  expect(find.byType(DeliveryHome), findsOneWidget);
});

});

I am not sure if I missed something I'm still beginner

Answer 1

testWidgets by default uses a Mocked http class which will always return HTTP error 400. This is likely why your code works in emulator, but not in tests.

To get actual HTTP responses from a web server prefix/setup before your test with: HttpOverrides.global = null;

Example

Provided by dnfield (on Google Flutter team).

See full github thread

import 'dart:io';

import 'package:flutter_test/flutter_test.dart';
import 'package:http/http.dart';

void main() {
  setUpAll(() {
    // ↓ required to avoid HTTP error 400 mocked returns
    HttpOverrides.global = null;
  });
  testWidgets('http', (WidgetTester tester) async {
    await tester.runAsync(() async {
      final HttpClient client = HttpClient();
      final HttpClientRequest request =
      await client.getUrl(Uri.parse('https://google.com'));

      final HttpClientResponse response = await request.close();
      print(response.statusCode);  // Should get 200
    });
  });

  testWidgets('http2', (WidgetTester tester) async {
    await tester.runAsync(() async {
      final result = await get(Uri.parse('https://google.com'));
      print(result.statusCode); // Should get 200
    });
  });
}