flutter/packages/flutter_test/test/controller_test.dart

// Copyright 2016 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'dart:ui';

import 'package:flutter/material.dart';
import 'package:flutter/widgets.dart';
import 'package:flutter_test/flutter_test.dart';
import 'package:flutter/gestures.dart';

class TestDragData {
  const TestDragData(
    this.slop,
    this.dragDistance,
    this.expectedOffsets,
  );

  final Offset slop;
  final Offset dragDistance;
  final List<Offset> expectedOffsets;
}

void main() {
  testWidgets(
    'WidgetTester.drag must break the offset into multiple parallel components if'
    'the drag goes outside the touch slop values',
    (WidgetTester tester) async {
      // This test checks to make sure that the total drag will be correctly split into
      // pieces such that the first (and potentially second) moveBy function call(s) in
      // controller.drag() will never have a component greater than the touch
      // slop in that component's respective axis.
      const List<TestDragData> offsetResults = <TestDragData>[
        TestDragData(
          Offset(10.0, 10.0),
          Offset(-150.0, 200.0),
          <Offset>[
            Offset(-7.5, 10.0),
            Offset(-2.5, 3.333333333333333),
            Offset(-140.0, 186.66666666666666),
          ],
        ),
        TestDragData(
          Offset(10.0, 10.0),
          Offset(150, -200),
          <Offset>[
            Offset(7.5, -10),
            Offset(2.5, -3.333333333333333),
            Offset(140.0, -186.66666666666666),
          ],
        ),
        TestDragData(
          Offset(10.0, 10.0),
          Offset(-200, 150),
          <Offset>[
            Offset(-10, 7.5),
            Offset(-3.333333333333333, 2.5),
            Offset(-186.66666666666666, 140.0),
          ],
        ),
        TestDragData(
          Offset(10.0, 10.0),
          Offset(200.0, -150.0),
          <Offset>[
            Offset(10, -7.5),
            Offset(3.333333333333333, -2.5),
            Offset(186.66666666666666, -140.0),
          ],
        ),
        TestDragData(
          Offset(10.0, 10.0),
          Offset(-150.0, -200.0),
          <Offset>[
            Offset(-7.5, -10.0),
            Offset(-2.5, -3.333333333333333),
            Offset(-140.0, -186.66666666666666),
          ],
        ),
        TestDragData(
          Offset(10.0, 10.0),
          Offset(8.0, 3.0),
          <Offset>[
            Offset(8.0, 3.0),
          ],
        ),
        TestDragData(
          Offset(10.0, 10.0),
          Offset(3.0, 8.0),
          <Offset>[
            Offset(3.0, 8.0),
          ],
        ),
        TestDragData(
          Offset(10.0, 10.0),
          Offset(20.0, 5.0),
          <Offset>[
            Offset(10.0, 2.5),
            Offset(10.0, 2.5),
          ],
        ),
        TestDragData(
          Offset(10.0, 10.0),
          Offset(5.0, 20.0),
          <Offset>[
            Offset(2.5, 10.0),
            Offset(2.5, 10.0),
          ],
        ),
        TestDragData(
          Offset(10.0, 10.0),
          Offset(20.0, 15.0),
          <Offset>[
            Offset(10.0, 7.5),
            Offset(3.333333333333333, 2.5),
            Offset(6.666666666666668, 5.0),
          ],
        ),
        TestDragData(
          Offset(10.0, 10.0),
          Offset(15.0, 20.0),
          <Offset>[
            Offset(7.5, 10.0),
            Offset(2.5, 3.333333333333333),
            Offset(5.0, 6.666666666666668),
          ],
        ),
        TestDragData(
          Offset(10.0, 10.0),
          Offset(20.0, 20.0),
          <Offset>[
            Offset(10.0, 10.0),
            Offset(10.0, 10.0),
          ],
        ),
        TestDragData(
          Offset(10.0, 10.0),
          Offset(0.0, 5.0),
          <Offset>[
            Offset(0.0, 5.0),
          ],
        ),

        //// Varying touch slops
        TestDragData(
          Offset(12.0, 5.0),
          Offset(0.0, 5.0),
          <Offset>[
            Offset(0.0, 5.0),
          ],
        ),
        TestDragData(
          Offset(12.0, 5.0),
          Offset(20.0, 5.0),
          <Offset>[
            Offset(12.0, 3.0),
            Offset(8.0, 2.0),
          ],
        ),
        TestDragData(
          Offset(12.0, 5.0),
          Offset(5.0, 20.0),
          <Offset>[
            Offset(1.25, 5.0),
            Offset(3.75, 15.0),
          ],
        ),
        TestDragData(
          Offset(5.0, 12.0),
          Offset(5.0, 20.0),
          <Offset>[
            Offset(3.0, 12.0),
            Offset(2.0, 8.0),
          ],
        ),
        TestDragData(
          Offset(5.0, 12.0),
          Offset(20.0, 5.0),
          <Offset>[
            Offset(5.0, 1.25),
            Offset(15.0, 3.75),
          ],
        ),
        TestDragData(
          Offset(18.0, 18.0),
          Offset(0.0, 150.0),
          <Offset>[
            Offset(0.0, 18.0),
            Offset(0.0, 132.0),
          ],
        ),
        TestDragData(
          Offset(18.0, 18.0),
          Offset(0.0, -150.0),
          <Offset>[
            Offset(0.0, -18.0),
            Offset(0.0, -132.0),
          ],
        ),
        TestDragData(
          Offset(18.0, 18.0),
          Offset(-150.0, 0.0),
          <Offset>[
            Offset(-18.0, 0.0),
            Offset(-132.0, 0.0),
          ],
        ),
        TestDragData(
          Offset(0.0, 0.0),
          Offset(-150.0, 0.0),
          <Offset>[
            Offset(-150.0, 0.0),
          ],
        ),
        TestDragData(
          Offset(18.0, 18.0),
          Offset(-32.0, 0.0),
          <Offset>[
            Offset(-18.0, 0.0),
            Offset(-14.0, 0.0),
          ],
        ),
      ];

      final List<Offset> dragOffsets = <Offset>[];

      await tester.pumpWidget(
        Listener(
          onPointerMove: (PointerMoveEvent event) {
            dragOffsets.add(event.delta);
          },
          child: const Text('test', textDirection: TextDirection.ltr),
        ),
      );

      for (int resultIndex = 0; resultIndex < offsetResults.length; resultIndex += 1) {
        final TestDragData testResult = offsetResults[resultIndex];
        await tester.drag(
          find.text('test'),
          testResult.dragDistance,
          touchSlopX: testResult.slop.dx,
          touchSlopY: testResult.slop.dy,
        );
        expect(
          testResult.expectedOffsets.length,
          dragOffsets.length,
          reason:
            'There is a difference in the number of expected and actual split offsets for the drag with:\n'
            'Touch Slop: ${testResult.slop}\n'
            'Delta:      ${testResult.dragDistance}\n',
        );
        for (int valueIndex = 0; valueIndex < offsetResults[resultIndex].expectedOffsets.length; valueIndex += 1) {
          expect(
            testResult.expectedOffsets[valueIndex],
            offsetMoreOrLessEquals(dragOffsets[valueIndex]),
            reason:
              'There is a difference in the expected and actual value of the ' +
              (valueIndex == 2 ? 'first' : valueIndex == 3 ? 'second' : 'third') +
              ' split offset for the drag with:\n'
              'Touch slop: ${testResult.slop}\n'
              'Delta:      ${testResult.dragDistance}\n'
          );
        }
        dragOffsets.clear();
      }
    },
  );
}