Test the use of alt with no value

This link contains an image that only has alt.

<a href="foo.html">

  <img src="http://our.umbraco.org/media/avatar/3042.jpg" alt >

</a> 

This image has alt.

<img src="http://our.umbraco.org/media/avatar/3042.jpg" alt > 

This image that has alt="".

<img src="http://our.umbraco.org/media/avatar/3042.jpg" alt="" > 

This image has no alt attribute.

<img src="http://our.umbraco.org/media/avatar/3042.jpg"  > 

Results

The alt attribute is being treated as alt="" by VoiceOver and I would assume other screen readers. The link that includes an image with alt announces the link's url. The images with alt and alt="" are ignored. The image without an alt attribute announces the image's src.