act.tap(spotText('textSpan')) should click the exact TextSpan

[passsy]

Currently, act.tap() taps the center of the RenderObject. But RenderParagraph can give the exact location of the text and there should be clicked, allowing TextSpans with gesture recognizers.

      Offset locationOfTextSpan(String text) {
        assert(text.length > 1);
        final paragraph =
            spotText(text).snapshotRenderObject() as RenderParagraph;
        final fullText = paragraph.text.toPlainText();
        final start = fullText.indexOf(text);
        final end = start + text.length;
        final barLocationStart =
            paragraph.getOffsetForCaret(TextPosition(offset: start), Rect.zero);
        final barLocationEnd =
            paragraph.getOffsetForCaret(TextPosition(offset: end), Rect.zero);
        if (barLocationStart.dy == barLocationEnd.dy) {
          // on same line, click the middle
          return Offset(
            (barLocationStart.dx + barLocationEnd.dx) / 2,
            (barLocationStart.dy + barLocationEnd.dy) / 2,
          );
        } else {
          // click one pixel inside the first character
          return barLocationStart + const Offset(1, 1);
        }
      }

      Future<void> tapTextSpan(String text) async {
        final spanLocation = locationOfTextSpan(text);

        final binding = TestWidgetsFlutterBinding.instance;
        final downEvent = PointerDownEvent(position: spanLocation);
        binding.handlePointerEvent(downEvent);

        final upEvent = PointerUpEvent(position: spanLocation);
        binding.handlePointerEvent(upEvent);
      }

      testWidgets('concatenates text spans', (tester) async {
        await tester.pumpWidget(
          _stage(
            children: [
              RichText(
                text: TextSpan(
                  children: [
                    TextSpan(text: 'foo'),
                    TextSpan(
                      text: 'bar',
                      recognizer: TapGestureRecognizer()
                        ..onTap = () => print('click'),
                    ),
                  ],
                ),
              ),
            ],
          ),
        );

        spotText('foo').existsOnce();
        spotText('foobar').existsOnce();

        await tapTextSpan('bar');
      });

This example should be the default