chromium/src/third_party/blink/web_tests/editing/selection/rangeCount.html

<p>This tests Selection::rangeCount.  You should see "Hello World" selected below.  You should not see any failures below.</p>
<div id="div" contenteditable="true">Hello World</div>
<ul id="console"></ul>
<script>
function log(str) {
    var li = document.createElement("li");
    li.appendChild(document.createTextNode(str));
    var console = document.getElementById("console");
    console.appendChild(li);
}

function runTest() {
    
    try {
        if (window.testRunner)
            testRunner.dumpAsText();
            
        var div = document.getElementById("div");
        var text = div.firstChild;
        var sel = window.getSelection();
            
        if (sel.rangeCount == undefined) {
            log("Selection::rangeCount not implemented.");
            return;
        }
        
        if (sel.rangeCount != 0)
            log("Failure.  Expected: rangeCount == 0, Found: " + sel.rangeCount);
        
        sel.collapse(text, 0);
        if (sel.rangeCount != 1)
            log("Failure.  Expected: rangeCount == 1, Found: " + sel.rangeCount);
        
        document.execCommand("SelectAll");
        if (sel.rangeCount != 1)
            log("Failure.  Expected: rangeCount == 1, Found: " + sel.rangeCount);
        
    } catch(e) {
        log(e);
    }
}

runTest();
</script>