haracterIndex = 2
    const x = rect.left + characterWidth * characterIndex;
    const y = rect.top + rect.height / 2;
    const caretPosition = document.caretPositionFromPoint(x, y);
    const caretRangeExpected = new Range();
    caretRangeExpected.setStart(textDiv.firstChild, characterIndex);
    caretRectExpected = caretRangeExpected.getBoundingClientRect();
    assert_true(caretPosition.getClientRect instanceof Function);
    const caretRectActual = caretPosition.getClientRect();
    assert_true(caretR