chromium/third_party/blink/renderer/core/testing/data/longpress_selection.html

<!DOCTYPE html>
<html>
<head>
<style>
span {
    font-size: 300%;
}
</style>
</head>
<body>
Hello this is some text for testing. Here is a
<span id="target" contenteditable>
testword
</span>
that we should be able to select by longpressing.

To test onselectstart, here is
<span id="onselectstartfalse" onselectstart="return false;">
anotherbitoftext
</span>
that we should not be able to select.
</body>
</html>