// Copyright 2014 The Flutter 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 'package:flutter/physics.dart'; import 'package:flutter_test/flutter_test.dart'; void main() { test('Friction simulation positive velocity', () { final FrictionSimulation friction = FrictionSimulation(0.135, 100.0, 100.0); expect(friction.x(0.0), moreOrLessEquals(100.0)); expect(friction.dx(0.0), moreOrLessEquals(100.0)); expect(friction.x(0.1), moreOrLessEquals(110.0, epsilon: 1.0)); expect(friction.x(0.5), moreOrLessEquals(131.0, epsilon: 1.0)); expect(friction.x(2.0), moreOrLessEquals(149.0, epsilon: 1.0)); expect(friction.finalX, moreOrLessEquals(149.0, epsilon: 1.0)); expect(friction.timeAtX(100.0), 0.0); expect(friction.timeAtX(friction.x(0.1)), moreOrLessEquals(0.1)); expect(friction.timeAtX(friction.x(0.5)), moreOrLessEquals(0.5)); expect(friction.timeAtX(friction.x(2.0)), moreOrLessEquals(2.0)); expect(friction.timeAtX(-1.0), double.infinity); expect(friction.timeAtX(200.0), double.infinity); }); test('Friction simulation negative velocity', () { final FrictionSimulation friction = FrictionSimulation(0.135, 100.0, -100.0); expect(friction.x(0.0), moreOrLessEquals(100.0)); expect(friction.dx(0.0), moreOrLessEquals(-100.0)); expect(friction.x(0.1), moreOrLessEquals(91.0, epsilon: 1.0)); expect(friction.x(0.5), moreOrLessEquals(68.0, epsilon: 1.0)); expect(friction.x(2.0), moreOrLessEquals(51.0, epsilon: 1.0)); expect(friction.finalX, moreOrLessEquals(50, epsilon: 1.0)); expect(friction.timeAtX(100.0), 0.0); expect(friction.timeAtX(friction.x(0.1)), moreOrLessEquals(0.1)); expect(friction.timeAtX(friction.x(0.5)), moreOrLessEquals(0.5)); expect(friction.timeAtX(friction.x(2.0)), moreOrLessEquals(2.0)); expect(friction.timeAtX(101.0), double.infinity); expect(friction.timeAtX(40.0), double.infinity); }); test('Friction simulation constant deceleration', () { final FrictionSimulation friction = FrictionSimulation(0.135, 100.0, -100.0, constantDeceleration: 100); expect(friction.x(0.0), moreOrLessEquals(100.0)); expect(friction.dx(0.0), moreOrLessEquals(-100.0)); expect(friction.x(0.1), moreOrLessEquals(91.0, epsilon: 1.0)); expect(friction.x(0.5), moreOrLessEquals(80.0, epsilon: 1.0)); expect(friction.x(2.0), moreOrLessEquals(80.0, epsilon: 1.0)); expect(friction.finalX, moreOrLessEquals(80.0, epsilon: 1.0)); expect(friction.timeAtX(100.0), 0.0); expect(friction.timeAtX(friction.x(0.1)), moreOrLessEquals(0.1)); expect(friction.timeAtX(friction.x(0.2)), moreOrLessEquals(0.2)); expect(friction.timeAtX(friction.x(0.3)), moreOrLessEquals(0.3)); expect(friction.timeAtX(101.0), double.infinity); expect(friction.timeAtX(40.0), double.infinity); }); }