Codebase Browser
chromium
Go to App

chromium/third_party/blink/web_tests/editing/selection/select_all/select_all_iframe.html 

<!doctype html>
<script src="../../../resources/testharness.js"></script>
<script src="../../../resources/testharnessreport.js"></script>
<iframe id="iframe"></iframe>
<script>
test(function() {
    var iframe = document.getElementById('iframe');
    iframe.contentDocument.body.innerText = 'foo bar';
    iframe.focus();
    iframe.contentDocument.execCommand('selectAll');

    var selection = window.getSelection();
    assert_equals(selection.anchorNode, null, 'anchorNode');
    assert_equals(selection.anchorOffset, 0, 'anchorOffset');
    assert_equals(selection.focusNode, null, 'focusNode');
    assert_equals(selection.focusOffset, 0, 'focusOffset');

    var selectionInFrame = iframe.contentDocument.defaultView.getSelection();
    var sample = iframe.contentDocument.body.firstChild;
    assert_equals(selectionInFrame.anchorNode, sample, 'anchorNode');
    assert_equals(selectionInFrame.anchorOffset, 0, 'anchorOffset');
    assert_equals(selectionInFrame.focusNode, sample, 'focusNode');
    assert_equals(selectionInFrame.focusOffset, 7, 'focusOffset');

}, 'SelectAll command in IFRAME selects only content of IFRAME');
</script>