// Copyright 2017 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' as ui;

import 'package:flutter/painting.dart';
import 'package:flutter_test/flutter_test.dart';

void main() {
  test('TextPainter caret test', () {
    final TextPainter painter = TextPainter()
      ..textDirection = TextDirection.ltr;

    String text = 'A';
    painter.text = TextSpan(text: text);
    painter.layout();

    Offset caretOffset = painter.getOffsetForCaret(
      const ui.TextPosition(offset: 0),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, 0);
    caretOffset = painter.getOffsetForCaret(ui.TextPosition(offset: text.length), ui.Rect.zero);
    expect(caretOffset.dx, painter.width);

    // Check that getOffsetForCaret handles a character that is encoded as a surrogate pair.
    text = 'A\u{1F600}';
    painter.text = TextSpan(text: text);
    painter.layout();
    caretOffset = painter.getOffsetForCaret(ui.TextPosition(offset: text.length), ui.Rect.zero);
    expect(caretOffset.dx, painter.width);
  });

  test('TextPainter null text test', () {
    final TextPainter painter = TextPainter()
      ..textDirection = TextDirection.ltr;

    List<TextSpan> children = <TextSpan>[const TextSpan(text: 'B'), const TextSpan(text: 'C')];
    painter.text = TextSpan(text: null, children: children);
    painter.layout();

    Offset caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 0), ui.Rect.zero);
    expect(caretOffset.dx, 0);
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 1), ui.Rect.zero);
    expect(caretOffset.dx, painter.width / 2);
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 2), ui.Rect.zero);
    expect(caretOffset.dx, painter.width);

    children = <TextSpan>[];
    painter.text = TextSpan(text: null, children: children);
    painter.layout();

    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 0), ui.Rect.zero);
    expect(caretOffset.dx, 0);
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 1), ui.Rect.zero);
    expect(caretOffset.dx, 0);
  });

  test('TextPainter caret emoji test', () {
    final TextPainter painter = TextPainter()
      ..textDirection = TextDirection.ltr;

    // Format: '👩‍<zwj>👩‍<zwj>👦👩‍<zwj>👩‍<zwj>👧‍<zwj>👧🇺🇸'
    // One three-person family, one four person family, one US flag.
    const String text = '👩‍👩‍👦👩‍👩‍👧‍👧🇺🇸';
    painter.text = const TextSpan(text: text);
    painter.layout(maxWidth: 10000);

    expect(text.length, 23);

    Offset caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 0), ui.Rect.zero);
    expect(caretOffset.dx, 0); // 👩‍
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: text.length), ui.Rect.zero);
    expect(caretOffset.dx, painter.width);

    // Two UTF-16 codepoints per emoji, one codepoint per zwj
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 1), ui.Rect.zero);
    expect(caretOffset.dx, 42); // 👩‍
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 2), ui.Rect.zero);
    expect(caretOffset.dx, 42); // <zwj>
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 3), ui.Rect.zero);
    expect(caretOffset.dx, 42); // 👩‍
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 4), ui.Rect.zero);
    expect(caretOffset.dx, 42); // 👩‍
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 5), ui.Rect.zero);
    expect(caretOffset.dx, 42); // <zwj>
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 6), ui.Rect.zero);
    expect(caretOffset.dx, 42); // 👦
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 7), ui.Rect.zero);
    expect(caretOffset.dx, 42); // 👦
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 8), ui.Rect.zero);
    expect(caretOffset.dx, 42); // 👩‍
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 9), ui.Rect.zero);
    expect(caretOffset.dx, 98); // 👩‍
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 10), ui.Rect.zero);
    expect(caretOffset.dx, 98); // <zwj>
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 11), ui.Rect.zero);
    expect(caretOffset.dx, 98); // 👩‍
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 12), ui.Rect.zero);
    expect(caretOffset.dx, 98); // 👩‍
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 13), ui.Rect.zero);
    expect(caretOffset.dx, 98); // <zwj>
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 14), ui.Rect.zero);
    expect(caretOffset.dx, 98); // 👧‍
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 15), ui.Rect.zero);
    expect(caretOffset.dx, 98); // 👧‍
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 16), ui.Rect.zero);
    expect(caretOffset.dx, 98); // <zwj>
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 17), ui.Rect.zero);
    expect(caretOffset.dx, 98); // 👧
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 18), ui.Rect.zero);
    expect(caretOffset.dx, 98); // 👧
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 19), ui.Rect.zero);
    expect(caretOffset.dx, 98); // 🇺
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 20), ui.Rect.zero);
    expect(caretOffset.dx, 112); // 🇺
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 21), ui.Rect.zero);
    expect(caretOffset.dx, 112); // 🇸
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 22), ui.Rect.zero);
    expect(caretOffset.dx, 112); // 🇸
  });

  test('TextPainter caret center space test', () {
    final TextPainter painter = TextPainter()
      ..textDirection = TextDirection.ltr;

    const String text = 'test text with space at end   ';
    painter.text = const TextSpan(text: text);
    painter.textAlign = TextAlign.center;
    painter.layout();

    Offset caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 0), ui.Rect.zero);
    expect(caretOffset.dx, 21);
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: text.length), ui.Rect.zero);
    expect(caretOffset.dx, 441);

    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 1), ui.Rect.zero);
    expect(caretOffset.dx, 35);
    caretOffset = painter.getOffsetForCaret(const ui.TextPosition(offset: 2), ui.Rect.zero);
    expect(caretOffset.dx, 49);
  });

  test('TextPainter error test', () {
    final TextPainter painter = TextPainter(textDirection: TextDirection.ltr);
    expect(() { painter.paint(null, Offset.zero); }, throwsFlutterError);
  });

  test('TextPainter requires textDirection', () {
    final TextPainter painter1 = TextPainter(text: const TextSpan(text: ''));
    expect(() { painter1.layout(); }, throwsAssertionError);
    final TextPainter painter2 = TextPainter(text: const TextSpan(text: ''), textDirection: TextDirection.rtl);
    expect(() { painter2.layout(); }, isNot(throwsException));
  });

  test('TextPainter size test', () {
    final TextPainter painter = TextPainter(
      text: const TextSpan(
        text: 'X',
        style: TextStyle(
          inherit: false,
          fontFamily: 'Ahem',
          fontSize: 123.0,
        ),
      ),
      textDirection: TextDirection.ltr,
    );
    painter.layout();
    expect(painter.size, const Size(123.0, 123.0));
  });

  test('TextPainter textScaleFactor test', () {
    final TextPainter painter = TextPainter(
      text: const TextSpan(
        text: 'X',
        style: TextStyle(
          inherit: false,
          fontFamily: 'Ahem',
          fontSize: 10.0,
        ),
      ),
      textDirection: TextDirection.ltr,
      textScaleFactor: 2.0,
    );
    painter.layout();
    expect(painter.size, const Size(20.0, 20.0));
  });

  test('TextPainter default text height is 14 pixels', () {
    final TextPainter painter = TextPainter(
      text: const TextSpan(text: 'x'),
      textDirection: TextDirection.ltr,
    );
    painter.layout();
    expect(painter.preferredLineHeight, 14.0);
    expect(painter.size, const Size(14.0, 14.0));
  });

  test('TextPainter sets paragraph size from root', () {
    final TextPainter painter = TextPainter(
      text: const TextSpan(text: 'x', style: TextStyle(fontSize: 100.0)),
      textDirection: TextDirection.ltr,
    );
    painter.layout();
    expect(painter.preferredLineHeight, 100.0);
    expect(painter.size, const Size(100.0, 100.0));
  });

  test('TextPainter intrinsic dimensions', () {
    const TextStyle style = TextStyle(
      inherit: false,
      fontFamily: 'Ahem',
      fontSize: 10.0,
    );
    TextPainter painter;

    painter = TextPainter(
      text: const TextSpan(
        text: 'X X X',
        style: style,
      ),
      textDirection: TextDirection.ltr,
    );
    painter.layout();
    expect(painter.size, const Size(50.0, 10.0));
    expect(painter.minIntrinsicWidth, 10.0);
    expect(painter.maxIntrinsicWidth, 50.0);

    painter = TextPainter(
      text: const TextSpan(
        text: 'X X X',
        style: style,
      ),
      textDirection: TextDirection.ltr,
      ellipsis: 'e',
    );
    painter.layout();
    expect(painter.size, const Size(50.0, 10.0));
    expect(painter.minIntrinsicWidth, 50.0);
    expect(painter.maxIntrinsicWidth, 50.0);

    painter = TextPainter(
      text: const TextSpan(
        text: 'X X XXXX',
        style: style,
      ),
      textDirection: TextDirection.ltr,
      maxLines: 2,
    );
    painter.layout();
    expect(painter.size, const Size(80.0, 10.0));
    expect(painter.minIntrinsicWidth, 40.0);
    expect(painter.maxIntrinsicWidth, 80.0);

    painter = TextPainter(
      text: const TextSpan(
        text: 'X X XXXX XX',
        style: style,
      ),
      textDirection: TextDirection.ltr,
      maxLines: 2,
    );
    painter.layout();
    expect(painter.size, const Size(110.0, 10.0));
    expect(painter.minIntrinsicWidth, 70.0);
    expect(painter.maxIntrinsicWidth, 110.0);

    painter = TextPainter(
      text: const TextSpan(
        text: 'XXXXXXXX XXXX XX X',
        style: style,
      ),
      textDirection: TextDirection.ltr,
      maxLines: 2,
    );
    painter.layout();
    expect(painter.size, const Size(180.0, 10.0));
    expect(painter.minIntrinsicWidth, 90.0);
    expect(painter.maxIntrinsicWidth, 180.0);

    painter = TextPainter(
      text: const TextSpan(
        text: 'X XX XXXX XXXXXXXX',
        style: style,
      ),
      textDirection: TextDirection.ltr,
      maxLines: 2,
    );
    painter.layout();
    expect(painter.size, const Size(180.0, 10.0));
    expect(painter.minIntrinsicWidth, 90.0);
    expect(painter.maxIntrinsicWidth, 180.0);
  }, skip: true); // https://github.com/flutter/flutter/issues/13512

  test('TextPainter handles newlines properly', () {
    final TextPainter painter = TextPainter()
      ..textDirection = TextDirection.ltr;

    const double SIZE_OF_A = 14.0; // square size of "a" character
    String text = 'aaa';
    painter.text = TextSpan(text: text);
    painter.layout();

    // getOffsetForCaret in a plain one-line string is the same for either affinity.
    int offset = 0;
    painter.text = TextSpan(text: text);
    painter.layout();
    Offset caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(SIZE_OF_A * offset, 0.0001));
    expect(caretOffset.dy, closeTo(0.0, 0.0001));
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: ui.TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(SIZE_OF_A * offset, 0.0001));
    expect(caretOffset.dy, closeTo(0.0, 0.0001));
    offset = 1;
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(SIZE_OF_A * offset, 0.0001));
    expect(caretOffset.dy, closeTo(0.0, 0.0001));
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: ui.TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(SIZE_OF_A * offset, 0.0001));
    expect(caretOffset.dy, closeTo(0.0, 0.0001));
    offset = 2;
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(SIZE_OF_A * offset, 0.0001));
    expect(caretOffset.dy, closeTo(0.0, 0.0001));
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: ui.TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(SIZE_OF_A * offset, 0.0001));
    expect(caretOffset.dy, closeTo(0.0, 0.0001));
    offset = 3;
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(SIZE_OF_A * offset, 0.0001));
    expect(caretOffset.dy, closeTo(0.0, 0.0001));
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: ui.TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(SIZE_OF_A * offset, 0.0001));
    expect(caretOffset.dy, closeTo(0.0, 0.0001));

    // For explicit newlines, getOffsetForCaret places the caret at the location
    // indicated by offset regardless of affinity.
    text = '\n\n';
    painter.text = TextSpan(text: text);
    painter.layout();
    offset = 0;
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(0.0, 0.0001));
    expect(caretOffset.dy, closeTo(0.0, 0.0001));
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: ui.TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(0.0, 0.0001));
    expect(caretOffset.dy, closeTo(0.0, 0.0001));
    offset = 1;
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(0.0, 0.0001));
    expect(caretOffset.dy, closeTo(SIZE_OF_A, 0.0001));
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: ui.TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(0.0, 0.0001));
    expect(caretOffset.dy, closeTo(SIZE_OF_A, 0.0001));
    offset = 2;
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(0.0, 0.0001));
    expect(caretOffset.dy, closeTo(SIZE_OF_A * 2, 0.0001));
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: ui.TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(0.0, 0.0001));
    expect(caretOffset.dy, closeTo(SIZE_OF_A * 2, 0.0001));

    // getOffsetForCaret in an unwrapped string with explicit newlines is the
    // same for either affinity.
    text = '\naaa';
    painter.text = TextSpan(text: text);
    painter.layout();
    offset = 0;
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(0.0, 0.0001));
    expect(caretOffset.dy, closeTo(0.0, 0.0001));
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: ui.TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(0.0, 0.0001));
    expect(caretOffset.dy, closeTo(0.0, 0.0001));
    offset = 1;
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(0.0, 0.0001));
    expect(caretOffset.dy, closeTo(SIZE_OF_A, 0.0001));
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: ui.TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(0.0, 0.0001));
    expect(caretOffset.dy, closeTo(SIZE_OF_A, 0.0001));

    // When text wraps on its own, getOffsetForCaret disambiguates between the
    // end of one line and start of next using affinity.
    text = 'aaaaaaaa'; // Just enough to wrap one character down to second line
    painter.text = TextSpan(text: text);
    painter.layout(maxWidth: 100); // SIZE_OF_A * text.length > 100, so it wraps
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: text.length - 1),
      ui.Rect.zero,
    );
    // When affinity is downstream, cursor is at beginning of second line
    expect(caretOffset.dx, closeTo(0.0, 0.0001));
    expect(caretOffset.dy, closeTo(SIZE_OF_A, 0.0001));
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: text.length - 1, affinity: ui.TextAffinity.upstream),
      ui.Rect.zero,
    );
    // When affinity is upstream, cursor is at end of first line
    expect(caretOffset.dx, closeTo(98.0, 0.0001));
    expect(caretOffset.dy, closeTo(0.0, 0.0001));

    // When given a string with a newline at the end, getOffsetForCaret puts
    // the cursor at the start of the next line regardless of affinity
    text = 'aaa\n';
    painter.text = TextSpan(text: text);
    painter.layout();
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: text.length),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(0.0, 0.0001));
    expect(caretOffset.dy, closeTo(SIZE_OF_A, 0.0001));
    offset = text.length;
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(0.0, 0.0001));
    expect(caretOffset.dy, closeTo(SIZE_OF_A, 0.0001));

    // Given a one-line right aligned string, positioning the cursor at offset 0
    // means that it appears at the "end" of the string, after the character
    // that was typed first, at x=0.
    painter.textAlign = TextAlign.right;
    text = 'aaa';
    painter.text = TextSpan(text: text);
    painter.layout();
    offset = 0;
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(0.0, 0.0001));
    expect(caretOffset.dy, closeTo(0.0, 0.0001));
    painter.textAlign = TextAlign.left;

    // When given an offset after a newline in the middle of a string,
    // getOffsetForCaret returns the start of the next line regardless of
    // affinity.
    text = 'aaa\naaa';
    painter.text = TextSpan(text: text);
    painter.layout();
    offset = 4;
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(0.0, 0.0001));
    expect(caretOffset.dy, closeTo(SIZE_OF_A, 0.0001));
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(0.0, 0.0001));
    expect(caretOffset.dy, closeTo(SIZE_OF_A, 0.0001));

    // When given a string with multiple trailing newlines, places the caret
    // in the position given by offset regardless of affinity.
    text = 'aaa\n\n\n';
    offset = 3;
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(SIZE_OF_A * 3, 0.0001));
    expect(caretOffset.dy, closeTo(0.0, 0.0001));
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(SIZE_OF_A * 3, 0.0001));
    expect(caretOffset.dy, closeTo(0.0, 0.0001));

    offset = 4;
    painter.text = TextSpan(text: text);
    painter.layout();
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(0.0, 0.0001));
    expect(caretOffset.dy, closeTo(SIZE_OF_A, 0.001));
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(0.0, 0.0001));
    expect(caretOffset.dy, closeTo(SIZE_OF_A, 0.0001));

    offset = 5;
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(0.0, 0.0001));
    expect(caretOffset.dy, closeTo(SIZE_OF_A * 2, 0.001));
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(0.0, 0.0001));
    expect(caretOffset.dy, closeTo(SIZE_OF_A * 2, 0.0001));

    offset = 6;
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(0.0, 0.0001));
    expect(caretOffset.dy, closeTo(SIZE_OF_A * 3, 0.0001));

    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(0.0, 0.0001));
    expect(caretOffset.dy, closeTo(SIZE_OF_A * 3, 0.0001));

    // When given a string with multiple leading newlines, places the caret in
    // the position given by offset regardless of affinity.
    text = '\n\n\naaa';
    offset = 3;
    painter.text = TextSpan(text: text);
    painter.layout();
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(0.0, 0.0001));
    expect(caretOffset.dy, closeTo(SIZE_OF_A * 3, 0.0001));
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(0.0, 0.0001));
    expect(caretOffset.dy, closeTo(SIZE_OF_A * 3, 0.0001));

    offset = 2;
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(0.0, 0.0001));
    expect(caretOffset.dy, closeTo(SIZE_OF_A * 2, 0.0001));
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(0.0, 0.0001));
    expect(caretOffset.dy, closeTo(SIZE_OF_A * 2, 0.0001));

    offset = 1;
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(0.0, 0.0001));
    expect(caretOffset.dy,closeTo(SIZE_OF_A, 0.0001));
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(0.0, 0.0001));
    expect(caretOffset.dy, closeTo(SIZE_OF_A, 0.0001));

    offset = 0;
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(0.0, 0.0001));
    expect(caretOffset.dy, closeTo(0.0, 0.0001));
    caretOffset = painter.getOffsetForCaret(
      ui.TextPosition(offset: offset, affinity: TextAffinity.upstream),
      ui.Rect.zero,
    );
    expect(caretOffset.dx, closeTo(0.0, 0.0001));
    expect(caretOffset.dy, closeTo(0.0, 0.0001));
  });
}