/// Returns the [TextRange] of the line at the given [TextPosition].
///
/// The newline (if any) is returned as part of the range.
///
/// Not valid until after layout.
///
/// This can potentially be expensive, since it needs to compute the line
/// metrics, so use it sparingly.
TextRange getLineBoundary(TextPosition position)

test('getLineBoundary includes newline characters', () {
  const text = 'aaa\nbbb';

  final paragraphStyle = ui.ParagraphStyle(
    textDirection: ui.TextDirection.ltr,
  );
  final paragraphBuilder = ui.ParagraphBuilder(paragraphStyle)
    ..addText(text);
  final constraints = ui.ParagraphConstraints(width: 1000);
  final paragraph = paragraphBuilder.build();
  paragraph.layout(constraints);

  var range = paragraph.getLineBoundary(const TextPosition(offset: 0));
  expect(
    range.textInside(text),
    equals('aaa\n'),  // actual: aaa
  );
  expect(range.start, 0);
  expect(range.end, 4); // actual: 3

  range = paragraph.getLineBoundary(const TextPosition(offset: 5));
  expect(
    range.textInside(text),
    equals('bbb'),
  );
  expect(range.start, 4);
  expect(range.end, 7);
});