chromium/third_party/blink/web_tests/fast/dom/HTMLImageElement/image-alt-text.html

<html>
<head>
</head>
<body>
This tests whether alt text is shown for image elements with no src attribute.
You should see "Success" twice, followed by a blue rectangle.
<p>
<img alt="Success"><br>
<img alt="Success" width="100" height="50" border="1"><br>

<img src="resources/blue_rect.jpg" alt="FAILED!"><br>
</body>
</html>