// Copyright 2013 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:test/bootstrap/browser.dart';
import 'package:test/test.dart';
import 'package:ui/src/engine.dart';
import 'package:ui/ui.dart' as ui;

import '../../common/rendering.dart';
import '../../common/test_initialization.dart';
import '../paragraph/helper.dart';

void main() {
  internalBootstrapBrowserTest(() => testMain);
}

Future<void> testMain() async {
  setUpUnitTests();

  group('$CanvasParagraph.getBoxesForRange', () {
    test('return empty list for invalid ranges', () {
      final CanvasParagraph paragraph = rich(ahemStyle, (CanvasParagraphBuilder builder) {
        builder.addText('Lorem ipsum');
      })
        ..layout(constrain(double.infinity));

      expect(paragraph.getBoxesForRange(-1, 0), <ui.TextBox>[]);
      expect(paragraph.getBoxesForRange(0, 0), <ui.TextBox>[]);
      expect(paragraph.getBoxesForRange(11, 11), <ui.TextBox>[]);
      expect(paragraph.getBoxesForRange(11, 12), <ui.TextBox>[]);
      expect(paragraph.getBoxesForRange(4, 3), <ui.TextBox>[]);
    });

    test('handles single-line multi-span paragraphs', () {
      final CanvasParagraph paragraph = rich(ahemStyle, (CanvasParagraphBuilder builder) {
        builder.pushStyle(EngineTextStyle.only(color: blue));
        builder.addText('Lorem ');
        builder.pushStyle(EngineTextStyle.only(color: green));
        builder.addText('ipsum ');
        builder.pop();
        builder.addText('.');
      })
        ..layout(constrain(double.infinity));

      // Within the first span "Lorem ".

      expect(
        // "or"
        paragraph.getBoxesForRange(1, 3),
        <ui.TextBox>[
          box(10, 0, 30, 10),
        ],
      );
      expect(
        // "Lorem"
        paragraph.getBoxesForRange(0, 5),
        <ui.TextBox>[
          box(0, 0, 50, 10),
        ],
      );
      // Make sure the trailing space is also included in the box.
      expect(
        // "Lorem "
        paragraph.getBoxesForRange(0, 6),
        <ui.TextBox>[
          // "Lorem"
          box(0, 0, 50, 10),
          // " "
          box(50, 0, 60, 10),
        ],
      );

      // Within the second span "ipsum ".

      expect(
        // "psum"
        paragraph.getBoxesForRange(7, 11),
        <ui.TextBox>[
          box(70, 0, 110, 10),
        ],
      );
      expect(
        // "um "
        paragraph.getBoxesForRange(9, 12),
        <ui.TextBox>[
          // "um"
          box(90, 0, 110, 10),
          // " "
          box(110, 0, 120, 10),
        ],
      );

      // Across the two spans "Lorem " and "ipsum ".

      expect(
        // "rem ipsum"
        paragraph.getBoxesForRange(2, 11),
        <ui.TextBox>[
          // "rem"
          box(20, 0, 50, 10),
          // " "
          box(50, 0, 60, 10),
          // "ipsum"
          box(60, 0, 110, 10),
        ],
      );

      // Across all spans "Lorem ", "ipsum ", ".".

      expect(
        // "Lorem ipsum ."
        paragraph.getBoxesForRange(0, 13),
        <ui.TextBox>[
          // "Lorem"
          box(0, 0, 50, 10),
          // " "
          box(50, 0, 60, 10),
          // "ipsum"
          box(60, 0, 110, 10),
          // " "
          box(110, 0, 120, 10),
          // "."
          box(120, 0, 130, 10),
        ],
      );
    });

    test('handles multi-line single-span paragraphs', () {
      final CanvasParagraph paragraph = rich(ahemStyle, (CanvasParagraphBuilder builder) {
        builder.addText('Lorem ipsum dolor sit');
      })
        ..layout(constrain(90.0));

      // Lines:
      //   "Lorem "
      //   "ipsum "
      //   "dolor sit"

      // Within the first line "Lorem ".

      expect(
        // "or"
        paragraph.getBoxesForRange(1, 3),
        <ui.TextBox>[
          box(10, 0, 30, 10),
        ],
      );
      // Make sure the trailing space at the end of line is also included in the
      // box.
      expect(
        // "Lorem "
        paragraph.getBoxesForRange(0, 6),
        <ui.TextBox>[
          // "Lorem"
          box(0, 0, 50, 10),
          // " "
          box(50, 0, 60, 10),
        ],
      );

      // Within the second line "ipsum ".

      expect(
        // "psum "
        paragraph.getBoxesForRange(7, 12),
        <ui.TextBox>[
          // "psum"
          box(10, 10, 50, 20),
          // " "
          box(50, 10, 60, 20),
        ],
      );

      // Across all lines.

      expect(
        //    "em "
        // "ipsum "
        // "dolor s"
        paragraph.getBoxesForRange(3, 19),
        <ui.TextBox>[
          // "em"
          box(30, 0, 50, 10),
          // " "
          box(50, 0, 60, 10),
          // "ipsum"
          box(0, 10, 50, 20),
          // " "
          box(50, 10, 60, 20),
          // "dolor"
          box(0, 20, 50, 30),
          // " "
          box(50, 20, 60, 30),
          // "s"
          box(60, 20, 70, 30),
        ],
      );
    });

    test('handles multi-line multi-span paragraphs', () {
      final CanvasParagraph paragraph = rich(ahemStyle, (CanvasParagraphBuilder builder) {
        builder.pushStyle(EngineTextStyle.only(color: blue));
        builder.addText('Lorem ipsum ');
        builder.pushStyle(EngineTextStyle.only(color: green));
        builder.addText('dolor ');
        builder.pop();
        builder.addText('sit');
      })
        ..layout(constrain(90.0));

      // Lines:
      //   "Lorem "
      //   "ipsum "
      //   "dolor sit"

      // Within the first line "Lorem ".

      expect(
        // "ore"
        paragraph.getBoxesForRange(1, 4),
        <ui.TextBox>[
          box(10, 0, 40, 10),
        ],
      );
      expect(
        // "Lorem "
        paragraph.getBoxesForRange(0, 6),
        <ui.TextBox>[
          // "Lorem"
          box(0, 0, 50, 10),
          // " "
          box(50, 0, 60, 10),
        ],
      );

      // Within the second line "ipsum ".

      expect(
        // "psum "
        paragraph.getBoxesForRange(7, 12),
        <ui.TextBox>[
          // "psum"
          box(10, 10, 50, 20),
          // " "
          box(50, 10, 60, 20),
        ],
      );

      // Within the third line "dolor sit" which is made of 2 spans.

      expect(
        // "lor sit"
        paragraph.getBoxesForRange(14, 21),
        <ui.TextBox>[
          // "lor"
          box(20, 20, 50, 30),
          // " "
          box(50, 20, 60, 30),
          // "sit"
          box(60, 20, 90, 30),
        ],
      );

      // Across all lines.

      expect(
        //    "em "
        // "ipsum "
        // "dolor s"
        paragraph.getBoxesForRange(3, 19),
        <ui.TextBox>[
          //    "em"
          box(30, 0, 50, 10),
          //    " "
          box(50, 0, 60, 10),
          // "ipsum"
          box(0, 10, 50, 20),
          // " "
          box(50, 10, 60, 20),
          // "dolor"
          box(0, 20, 50, 30),
          // " "
          box(50, 20, 60, 30),
          // "s"
          box(60, 20, 70, 30),
        ],
      );
    });

    test('handles spans with varying heights/baselines', () {
      final CanvasParagraph paragraph = rich(ahemStyle, (CanvasParagraphBuilder builder) {
        builder.pushStyle(EngineTextStyle.only(fontSize: 20.0));
        // width = 20.0 * 6 = 120.0
        // baseline = 20.0 * 80% = 16.0
        builder.addText('Lorem ');
        builder.pushStyle(EngineTextStyle.only(fontSize: 40.0));
        // width = 40.0 * 6 = 240.0
        // baseline = 40.0 * 80% = 32.0
        builder.addText('ipsum ');
        builder.pushStyle(EngineTextStyle.only(fontSize: 10.0));
        // width = 10.0 * 6 = 60.0
        // baseline = 10.0 * 80% = 8.0
        builder.addText('dolor ');
        builder.pushStyle(EngineTextStyle.only(fontSize: 30.0));
        // width = 30.0 * 4 = 120.0
        // baseline = 30.0 * 80% = 24.0
        builder.addText('sit ');
        builder.pushStyle(EngineTextStyle.only(fontSize: 20.0));
        // width = 20.0 * 4 = 80.0
        // baseline = 20.0 * 80% = 16.0
        builder.addText('amet');
      })
        ..layout(constrain(420.0));

      // Lines:
      //   "Lorem ipsum dolor " (width: 420, height: 40, baseline: 32)
      //   "sit amet"           (width: 200, height: 30, baseline: 24)

      expect(
        // "em ipsum dol"
        paragraph.getBoxesForRange(3, 15),
        <ui.TextBox>[
          // "em"
          box(60, 16, 100, 36),
          // " "
          box(100, 16, 120, 36),
          // "ipsum"
          box(120, 0, 320, 40),
          // " "
          box(320, 0, 360, 40),
          // "dol"
          box(360, 24, 390, 34),
        ],
      );

      expect(
        // "sum dolor "
        // "sit amet"
        paragraph.getBoxesForRange(8, 26),
        <ui.TextBox>[
          // "sum"
          box(200, 0, 320, 40),
          // " "
          box(320, 0, 360, 40),
          // "dolor"
          box(360, 24, 410, 34),
          // " "
          box(410, 24, 420, 34),
          // "sit"
          box(0, 40, 90, 70),
          // " "
          box(90, 40, 120, 70),
          // "amet"
          box(120, 48, 200, 68),
        ],
      );
    });

    test('reverts to last line break opportunity', () {
      final CanvasParagraph paragraph = rich(ahemStyle, (ui.ParagraphBuilder builder) {
        // Lines:
        //   "AAA "
        //   "B_C DD"
        builder.pushStyle(EngineTextStyle.only(color: blue));
        builder.addText('AAA B');
        builder.pushStyle(EngineTextStyle.only(color: green));
        builder.addText('_C ');
        builder.pushStyle(EngineTextStyle.only(color: green));
        builder.addText('DD');
      });

      String getTextForFragment(LayoutFragment fragment) {
        return paragraph.plainText.substring(fragment.start, fragment.end);
      }

      // The layout algorithm will keep appending segments to the line builder
      // until it reaches: "AAA B_". At that point, it'll try to add the "C" but
      // realizes there isn't enough width in the line. Since the line already
      // had a line break opportunity, the algorithm tries to revert the line to
      // that opportunity (i.e. "AAA ") and pops the segments "_" and "B".
      //
      // Because the segments "B" and "_" have different directionality
      // preferences (LTR and no-preferenece, respectively), the algorithm
      // should've already created a box for "B". When the "B" segment is popped
      // we want to make sure that the "B" box is also popped.
      paragraph.layout(constrain(60));

      final ParagraphLine firstLine = paragraph.lines[0];
      final ParagraphLine secondLine = paragraph.lines[1];

      // There should be no "B" in the first line's fragments.
      expect(firstLine.fragments, hasLength(2));

      expect(getTextForFragment(firstLine.fragments[0]), 'AAA');
      expect(firstLine.fragments[0].left, 0.0);

      expect(getTextForFragment(firstLine.fragments[1]), ' ');
      expect(firstLine.fragments[1].left, 30.0);

      // Make sure the second line isn't missing any fragments.
      expect(secondLine.fragments, hasLength(5));

      expect(getTextForFragment(secondLine.fragments[0]), 'B');
      expect(secondLine.fragments[0].left, 0.0);

      expect(getTextForFragment(secondLine.fragments[1]), '_');
      expect(secondLine.fragments[1].left, 10.0);

      expect(getTextForFragment(secondLine.fragments[2]), 'C');
      expect(secondLine.fragments[2].left, 20.0);

      expect(getTextForFragment(secondLine.fragments[3]), ' ');
      expect(secondLine.fragments[3].left, 30.0);

      expect(getTextForFragment(secondLine.fragments[4]), 'DD');
      expect(secondLine.fragments[4].left, 40.0);
    });
  });

  group('$CanvasParagraph.getPositionForOffset', () {
    test('handles single-line multi-span paragraphs', () {
      final CanvasParagraph paragraph = rich(ahemStyle, (CanvasParagraphBuilder builder) {
        builder.pushStyle(EngineTextStyle.only(color: blue));
        builder.addText('Lorem ');
        builder.pushStyle(EngineTextStyle.only(color: green));
        builder.addText('ipsum ');
        builder.pop();
        builder.addText('.');
      })
        ..layout(constrain(double.infinity));

      // Above the line, at the beginning.
      expect(
        paragraph.getPositionForOffset(const ui.Offset(0, -5)),
        pos(0, ui.TextAffinity.downstream),
      );
      // At the top left corner of the line.
      expect(
        paragraph.getPositionForOffset(ui.Offset.zero),
        pos(0, ui.TextAffinity.downstream),
      );
      // At the beginning of the line.
      expect(
        paragraph.getPositionForOffset(const ui.Offset(0, 5)),
        pos(0, ui.TextAffinity.downstream),
      );
      // Below the line, at the end.
      expect(
        paragraph.getPositionForOffset(const ui.Offset(130, 12)),
        pos(13, ui.TextAffinity.upstream),
      );
      // At the end of the line.
      expect(
        paragraph.getPositionForOffset(const ui.Offset(130, 5)),
        pos(13, ui.TextAffinity.upstream),
      );
      // On the left half of "p" in "ipsum".
      expect(
        paragraph.getPositionForOffset(const ui.Offset(74, 5)),
        pos(7, ui.TextAffinity.downstream),
      );
      // On the left half of "p" in "ipsum" (above the line).
      expect(
        paragraph.getPositionForOffset(const ui.Offset(74, -5)),
        pos(7, ui.TextAffinity.downstream),
      );
      // On the left half of "p" in "ipsum" (below the line).
      expect(
        paragraph.getPositionForOffset(const ui.Offset(74, 15)),
        pos(7, ui.TextAffinity.downstream),
      );
      // On the right half of "p" in "ipsum".
      expect(
        paragraph.getPositionForOffset(const ui.Offset(76, 5)),
        pos(8, ui.TextAffinity.upstream),
      );
      // At the top of the line, on the left half of "p" in "ipsum".
      expect(
        paragraph.getPositionForOffset(const ui.Offset(74, 0)),
        pos(7, ui.TextAffinity.downstream),
      );
      // At the top of the line, on the right half of "p" in "ipsum".
      expect(
        paragraph.getPositionForOffset(const ui.Offset(76, 0)),
        pos(8, ui.TextAffinity.upstream),
      );
    });

    test('handles multi-line single-span paragraphs', () {
      final CanvasParagraph paragraph = rich(ahemStyle, (CanvasParagraphBuilder builder) {
        builder.addText('Lorem ipsum dolor sit');
      })
        ..layout(constrain(90.0));

      // Lines:
      //   "Lorem "
      //   "ipsum "
      //   "dolor sit"

      // Above the first line, at the beginning.
      expect(
        paragraph.getPositionForOffset(const ui.Offset(0, -5)),
        pos(0, ui.TextAffinity.downstream),
      );
      // At the top left corner of the line.
      expect(
        paragraph.getPositionForOffset(ui.Offset.zero),
        pos(0, ui.TextAffinity.downstream),
      );
      // At the beginning of the first line.
      expect(
        paragraph.getPositionForOffset(const ui.Offset(0, 5)),
        pos(0, ui.TextAffinity.downstream),
      );
      // At the end of the first line.
      expect(
        paragraph.getPositionForOffset(const ui.Offset(60, 5)),
        pos(6, ui.TextAffinity.upstream),
      );
      // At the end of the first line (above the line).
      expect(
        paragraph.getPositionForOffset(const ui.Offset(60, -5)),
        pos(6, ui.TextAffinity.upstream),
      );
      // After the end of the first line to the right.
      expect(
        paragraph.getPositionForOffset(const ui.Offset(70, 5)),
        pos(6, ui.TextAffinity.upstream),
      );
      // On the left half of " " in "Lorem ".
      expect(
        paragraph.getPositionForOffset(const ui.Offset(54, 5)),
        pos(5, ui.TextAffinity.downstream),
      );
      // On the right half of " " in "Lorem ".
      expect(
        paragraph.getPositionForOffset(const ui.Offset(56, 5)),
        pos(6, ui.TextAffinity.upstream),
      );

      // At the beginning of the second line "ipsum ".
      expect(
        paragraph.getPositionForOffset(const ui.Offset(0, 15)),
        pos(6, ui.TextAffinity.downstream),
      );
      // At the end of the second line.
      expect(
        paragraph.getPositionForOffset(const ui.Offset(60, 15)),
        pos(12, ui.TextAffinity.upstream),
      );
      // After the end of the second line to the right.
      expect(
        paragraph.getPositionForOffset(const ui.Offset(70, 15)),
        pos(12, ui.TextAffinity.upstream),
      );

      // Below the third line "dolor sit", at the end.
      expect(
        paragraph.getPositionForOffset(const ui.Offset(90, 40)),
        pos(21, ui.TextAffinity.upstream),
      );
      // At the end of the third line.
      expect(
        paragraph.getPositionForOffset(const ui.Offset(90, 25)),
        pos(21, ui.TextAffinity.upstream),
      );
      // After the end of the third line to the right.
      expect(
        paragraph.getPositionForOffset(const ui.Offset(100, 25)),
        pos(21, ui.TextAffinity.upstream),
      );
      // On the left half of " " in "dolor sit".
      expect(
        paragraph.getPositionForOffset(const ui.Offset(54, 25)),
        pos(17, ui.TextAffinity.downstream),
      );
      // On the right half of " " in "dolor sit".
      expect(
        paragraph.getPositionForOffset(const ui.Offset(56, 25)),
        pos(18, ui.TextAffinity.upstream),
      );
    });

    test('handles multi-line multi-span paragraphs', () {
      final CanvasParagraph paragraph = rich(ahemStyle, (CanvasParagraphBuilder builder) {
        builder.pushStyle(EngineTextStyle.only(color: blue));
        builder.addText('Lorem ipsum ');
        builder.pushStyle(EngineTextStyle.only(color: green));
        builder.addText('dolor ');
        builder.pop();
        builder.addText('sit');
      })
        ..layout(constrain(90.0));

      // Lines:
      //   "Lorem "
      //   "ipsum "
      //   "dolor sit"

      // Above the first line, at the beginning.
      expect(
        paragraph.getPositionForOffset(const ui.Offset(0, -5)),
        pos(0, ui.TextAffinity.downstream),
      );
      // At the beginning of the first line.
      expect(
        paragraph.getPositionForOffset(const ui.Offset(0, 5)),
        pos(0, ui.TextAffinity.downstream),
      );
      // At the end of the first line.
      expect(
        paragraph.getPositionForOffset(const ui.Offset(60, 5)),
        pos(6, ui.TextAffinity.upstream),
      );
      // After the end of the first line to the right.
      expect(
        paragraph.getPositionForOffset(const ui.Offset(70, 5)),
        pos(6, ui.TextAffinity.upstream),
      );
      // On the left half of " " in "Lorem ".
      expect(
        paragraph.getPositionForOffset(const ui.Offset(54, 5)),
        pos(5, ui.TextAffinity.downstream),
      );
      // On the right half of " " in "Lorem ".
      expect(
        paragraph.getPositionForOffset(const ui.Offset(56, 5)),
        pos(6, ui.TextAffinity.upstream),
      );

      // At the beginning of the second line "ipsum ".
      expect(
        paragraph.getPositionForOffset(const ui.Offset(0, 15)),
        pos(6, ui.TextAffinity.downstream),
      );
      // At the end of the second line.
      expect(
        paragraph.getPositionForOffset(const ui.Offset(60, 15)),
        pos(12, ui.TextAffinity.upstream),
      );
      // After the end of the second line to the right.
      expect(
        paragraph.getPositionForOffset(const ui.Offset(70, 15)),
        pos(12, ui.TextAffinity.upstream),
      );

      // Below the third line "dolor sit", at the end.
      expect(
        paragraph.getPositionForOffset(const ui.Offset(90, 40)),
        pos(21, ui.TextAffinity.upstream),
      );
      // At the end of the third line.
      expect(
        paragraph.getPositionForOffset(const ui.Offset(90, 25)),
        pos(21, ui.TextAffinity.upstream),
      );
      // After the end of the third line to the right.
      expect(
        paragraph.getPositionForOffset(const ui.Offset(100, 25)),
        pos(21, ui.TextAffinity.upstream),
      );
      // On the left half of " " in "dolor sit".
      expect(
        paragraph.getPositionForOffset(const ui.Offset(54, 25)),
        pos(17, ui.TextAffinity.downstream),
      );
      // On the right half of " " in "dolor sit".
      expect(
        paragraph.getPositionForOffset(const ui.Offset(56, 25)),
        pos(18, ui.TextAffinity.upstream),
      );
    });
  });

  group('$CanvasParagraph.getLineBoundary', () {
    test('single-line', () {
      final CanvasParagraph paragraph = rich(ahemStyle, (CanvasParagraphBuilder builder) {
        builder.addText('One single line');
      })
        ..layout(constrain(400.0));

      // "One single line".length == 15
      for (int i = 0; i < 15; i++) {
        expect(
          paragraph.getLineBoundary(ui.TextPosition(offset: i)),
          const ui.TextRange(start: 0, end: 15),
          reason: 'failed at offset $i',
        );
      }
    });

    test('multi-line', () {
      final CanvasParagraph paragraph = rich(ahemStyle, (CanvasParagraphBuilder builder) {
        builder.addText('First line\n');
        builder.addText('Second line\n');
        builder.addText('Third line');
      })
        ..layout(constrain(400.0));

      // "First line\n".length == 11
      for (int i = 0; i < 11; i++) {
        expect(
          paragraph.getLineBoundary(ui.TextPosition(offset: i)),
          // The "\n" is not included in the line boundary.
          const ui.TextRange(start: 0, end: 10),
          reason: 'failed at offset $i',
        );
      }

      // "Second line\n".length == 12
      for (int i = 11; i < 23; i++) {
        expect(
          paragraph.getLineBoundary(ui.TextPosition(offset: i)),
          // The "\n" is not included in the line boundary.
          const ui.TextRange(start: 11, end: 22),
          reason: 'failed at offset $i',
        );
      }

      // "Third line".length == 10
      for (int i = 23; i < 33; i++) {
        expect(
          paragraph.getLineBoundary(ui.TextPosition(offset: i)),
          const ui.TextRange(start: 23, end: 33),
          reason: 'failed at offset $i',
        );
      }
    });
  });

  test('$CanvasParagraph.getWordBoundary', () {
    final ui.Paragraph paragraph = plain(ahemStyle, 'Lorem ipsum dolor');

    const ui.TextRange loremRange = ui.TextRange(start: 0, end: 5);
    expect(paragraph.getWordBoundary(const ui.TextPosition(offset: 0)), loremRange);
    expect(paragraph.getWordBoundary(const ui.TextPosition(offset: 1)), loremRange);
    expect(paragraph.getWordBoundary(const ui.TextPosition(offset: 2)), loremRange);
    expect(paragraph.getWordBoundary(const ui.TextPosition(offset: 3)), loremRange);
    expect(paragraph.getWordBoundary(const ui.TextPosition(offset: 4)), loremRange);

    const ui.TextRange firstSpace = ui.TextRange(start: 5, end: 6);
    expect(paragraph.getWordBoundary(const ui.TextPosition(offset: 5)), firstSpace);

    const ui.TextRange ipsumRange = ui.TextRange(start: 6, end: 11);
    expect(paragraph.getWordBoundary(const ui.TextPosition(offset: 6)), ipsumRange);
    expect(paragraph.getWordBoundary(const ui.TextPosition(offset: 7)), ipsumRange);
    expect(paragraph.getWordBoundary(const ui.TextPosition(offset: 8)), ipsumRange);
    expect(paragraph.getWordBoundary(const ui.TextPosition(offset: 9)), ipsumRange);
    expect(paragraph.getWordBoundary(const ui.TextPosition(offset: 10)), ipsumRange);

    const ui.TextRange secondSpace = ui.TextRange(start: 11, end: 12);
    expect(paragraph.getWordBoundary(const ui.TextPosition(offset: 11)), secondSpace);

    const ui.TextRange dolorRange = ui.TextRange(start: 12, end: 17);
    expect(paragraph.getWordBoundary(const ui.TextPosition(offset: 12)), dolorRange);
    expect(paragraph.getWordBoundary(const ui.TextPosition(offset: 13)), dolorRange);
    expect(paragraph.getWordBoundary(const ui.TextPosition(offset: 14)), dolorRange);
    expect(paragraph.getWordBoundary(const ui.TextPosition(offset: 15)), dolorRange);
    expect(paragraph.getWordBoundary(const ui.TextPosition(offset: 16)), dolorRange);

    const ui.TextRange endRange = ui.TextRange(start: 17, end: 17);
    expect(paragraph.getWordBoundary(const ui.TextPosition(offset: 17)), endRange);
  });

  test('$CanvasParagraph.getWordBoundary can handle text affinity', () {
    final ui.Paragraph paragraph = plain(ahemStyle, 'Lorem ipsum dolor');

    const ui.TextRange loremRange = ui.TextRange(start: 0, end: 5);
    expect(paragraph.getWordBoundary(const ui.TextPosition(offset: 4)), loremRange);
    expect(paragraph.getWordBoundary(const ui.TextPosition(offset: 5, affinity: ui.TextAffinity.upstream)), loremRange);
  });

  test('$CanvasParagraph.longestLine', () {
    final ui.Paragraph paragraph = plain(ahemStyle, 'abcd\nabcde abc');
    paragraph.layout(const ui.ParagraphConstraints(width: 80.0));
    expect(paragraph.longestLine, 50.0);
  });

  test('$CanvasParagraph.width should be a whole integer when shouldDisableRoundingHack is false', () {
    if (ui.ParagraphBuilder.shouldDisableRoundingHack) {
      ui.ParagraphBuilder.setDisableRoundingHack(false);
      addTearDown(() => ui.ParagraphBuilder.setDisableRoundingHack(true));
    }
    // The paragraph width is only rounded to a whole integer if
    // shouldDisableRoundingHack is false.
    assert(!ui.ParagraphBuilder.shouldDisableRoundingHack);
    final ui.Paragraph paragraph = plain(ahemStyle, 'abc');
    paragraph.layout(const ui.ParagraphConstraints(width: 30.8));

    expect(paragraph.width, 30);
    expect(paragraph.height, 10);
  });

  test('Render after dispose', () async {
    final ui.Paragraph paragraph = plain(ahemStyle, 'abc');
    paragraph.layout(const ui.ParagraphConstraints(width: 30.8));

    final ui.PictureRecorder recorder = ui.PictureRecorder();
    final ui.Canvas canvas = ui.Canvas(recorder);
    canvas.drawParagraph(paragraph, ui.Offset.zero);
    final ui.Picture picture = recorder.endRecording();

    paragraph.dispose();

    final ui.SceneBuilder builder = ui.SceneBuilder();
    builder.addPicture(ui.Offset.zero, picture);
    final ui.Scene scene = builder.build();

    await renderScene(scene);

    picture.dispose();
    scene.dispose();
  });
}

/// Shortcut to create a [ui.TextBox] with an optional [ui.TextDirection].
ui.TextBox box(
  double left,
  double top,
  double right,
  double bottom, [
  ui.TextDirection direction = ui.TextDirection.ltr,
]) {
  return ui.TextBox.fromLTRBD(left, top, right, bottom, direction);
}

/// Shortcut to create a [ui.TextPosition].
ui.TextPosition pos(int offset, ui.TextAffinity affinity) {
  return ui.TextPosition(offset: offset, affinity: affinity);
}