import 'package:flutter_test/flutter_test.dart';

void main() {
  test('when actual is int', () {
    expect(100, moreOrLessEquals(100));
  });

  test('when actual is double', () {
    expect(100.0, moreOrLessEquals(100));
  });
}

package:test_api                                    expect
package:flutter_test/src/widget_tester.dart 460:16  expect
test/a.dart 5:5                                     main.<fn>

Expected: 100.0 (±1e-10)
  Actual: <100>
   Which: 100 is not in the range of 100.0 (±1e-10).