packages/flutter/test/rendering/box_constraints_test.dart

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

void main() {
  test('BoxConstraints toString', () {
    expect(const BoxConstraints.expand().toString(), contains('biggest'));
    expect(const BoxConstraints().toString(), contains('unconstrained'));
    expect(const BoxConstraints.tightFor(width: 50.0).toString(), contains('w=50'));
  });

  test('BoxConstraints copyWith', () {
    const BoxConstraints constraints = BoxConstraints(
      minWidth: 3.0,
      maxWidth: 7.0,
      minHeight: 11.0,
      maxHeight: 17.0,
    );
    BoxConstraints copy = constraints.copyWith();
    expect(copy, equals(constraints));
    copy = constraints.copyWith(
      minWidth: 13.0,
      maxWidth: 17.0,
      minHeight: 111.0,
      maxHeight: 117.0,
    );
    expect(copy.minWidth, 13.0);
    expect(copy.maxWidth, 17.0);
    expect(copy.minHeight, 111.0);
    expect(copy.maxHeight, 117.0);
    expect(copy, isNot(equals(constraints)));
    expect(copy.hashCode, isNot(equals(constraints.hashCode)));
  });

  test('BoxConstraints operators', () {
    const BoxConstraints constraints = BoxConstraints(
      minWidth: 3.0,
      maxWidth: 7.0,
      minHeight: 11.0,
      maxHeight: 17.0,
    );
    BoxConstraints copy = constraints * 2.0;
    expect(copy.minWidth, 6.0);
    expect(copy.maxWidth, 14.0);
    expect(copy.minHeight, 22.0);
    expect(copy.maxHeight, 34.0);
    expect(copy / 2.0, equals(constraints));
    copy = constraints ~/ 2.0;
    expect(copy.minWidth, 1.0);
    expect(copy.maxWidth, 3.0);
    expect(copy.minHeight, 5.0);
    expect(copy.maxHeight, 8.0);
    copy = constraints % 3.0;
    expect(copy.minWidth, 0.0);
    expect(copy.maxWidth, 1.0);
    expect(copy.minHeight, 2.0);
    expect(copy.maxHeight, 2.0);
  });

  test('BoxConstraints lerp', () {
    expect(BoxConstraints.lerp(null, null, 0.5), isNull);
    const BoxConstraints constraints = BoxConstraints(
      minWidth: 3.0,
      maxWidth: 7.0,
      minHeight: 11.0,
      maxHeight: 17.0,
    );
    BoxConstraints copy = BoxConstraints.lerp(null, constraints, 0.5)!;
    expect(copy.minWidth, moreOrLessEquals(1.5));
    expect(copy.maxWidth, moreOrLessEquals(3.5));
    expect(copy.minHeight, moreOrLessEquals(5.5));
    expect(copy.maxHeight, moreOrLessEquals(8.5));
    copy = BoxConstraints.lerp(constraints, null, 0.5)!;
    expect(copy.minWidth, moreOrLessEquals(1.5));
    expect(copy.maxWidth, moreOrLessEquals(3.5));
    expect(copy.minHeight, moreOrLessEquals(5.5));
    expect(copy.maxHeight, moreOrLessEquals(8.5));
    copy = BoxConstraints.lerp(const BoxConstraints(
      minWidth: 13.0,
      maxWidth: 17.0,
      minHeight: 111.0,
      maxHeight: 117.0,
    ), constraints, 0.2)!;
    expect(copy.minWidth, moreOrLessEquals(11.0));
    expect(copy.maxWidth, moreOrLessEquals(15.0));
    expect(copy.minHeight, moreOrLessEquals(91.0));
    expect(copy.maxHeight, moreOrLessEquals(97.0));
  });

  test('BoxConstraints lerp with unbounded width', () {
    const BoxConstraints constraints1 = BoxConstraints(
      minWidth: double.infinity,
      minHeight: 10.0,
      maxHeight: 20.0,
    );
    const BoxConstraints constraints2 = BoxConstraints(
      minWidth: double.infinity,
      minHeight: 20.0,
      maxHeight: 30.0,
    );
    const BoxConstraints constraints3 = BoxConstraints(
      minWidth: double.infinity,
      minHeight: 15.0,
      maxHeight: 25.0,
    );
    expect(BoxConstraints.lerp(constraints1, constraints2, 0.5), constraints3);
  });

  test('BoxConstraints lerp with unbounded height', () {
    const BoxConstraints constraints1 = BoxConstraints(
      minWidth: 10.0,
      maxWidth: 20.0,
      minHeight: double.infinity,
    );
    const BoxConstraints constraints2 = BoxConstraints(
      minWidth: 20.0,
      maxWidth: 30.0,
      minHeight: double.infinity,
    );
    const BoxConstraints constraints3 = BoxConstraints(
      minWidth: 15.0,
      maxWidth: 25.0,
      minHeight: double.infinity,
    );
    expect(BoxConstraints.lerp(constraints1, constraints2, 0.5), constraints3);
  });

  test('BoxConstraints lerp from bounded to unbounded', () {
    const BoxConstraints constraints1 = BoxConstraints(
      minWidth: double.infinity,
      minHeight: double.infinity,
    );
    const BoxConstraints constraints2 = BoxConstraints(
      minWidth: 20.0,
      maxWidth: 30.0,
      minHeight: double.infinity,
    );
    const BoxConstraints constraints3 = BoxConstraints(
      minWidth: double.infinity,
      minHeight: 20.0,
      maxHeight: 30.0,
    );
    expect(() => BoxConstraints.lerp(constraints1, constraints2, 0.5), throwsAssertionError);
    expect(() => BoxConstraints.lerp(constraints1, constraints3, 0.5), throwsAssertionError);
    expect(() => BoxConstraints.lerp(constraints2, constraints3, 0.5), throwsAssertionError);
  });

  test('BoxConstraints normalize', () {
    const BoxConstraints constraints = BoxConstraints(
      minWidth: 3.0,
      maxWidth: 2.0,
      minHeight: 11.0,
      maxHeight: 18.0,
    );
    final BoxConstraints copy = constraints.normalize();
    expect(copy.minWidth, 3.0);
    expect(copy.maxWidth, 3.0);
    expect(copy.minHeight, 11.0);
    expect(copy.maxHeight, 18.0);
  });
}