chromium/third_party/blink/web_tests/accessibility/input-type-text-caret-position.html

<!DOCTYPE html>
<html>
  <head>
    <script src="../resources/js-test.js"></script>
  </head>
  <body>

    <input type="text" id="input" value="Line 1">

    <script>
        description("This tests that caret position is reported correctly for text input elements.");

        if (window.accessibilityController) {

            let input = document.getElementById('input');
            input.focus();
            window.inputAccessible =
                accessibilityController.accessibleElementById('input');

            for (let characterIndex = 0; characterIndex < 7; ++characterIndex) {
                input.setSelectionRange(characterIndex, characterIndex);
                shouldBe("inputAccessible", "inputAccessible.selectionAnchorObject");
                shouldBeEqualToNumber("inputAccessible.selectionAnchorOffset",
                    characterIndex);
                shouldBe("inputAccessible", "inputAccessible.selectionFocusObject");
                shouldBeEqualToNumber("inputAccessible.selectionFocusOffset",
                    characterIndex);
            }

        }
    </script>

  </body>
</html>