The group has finished the test case for provision of short text alternatives as required by WCAG Success Criterion 1.1.1.
Its core component is the text computation algorithm as defined in the current UAAG as well as the WAI-ARIA recommendation. This algorithm specifies how user agents should handle the different attributes that may be used to provide a textual alternative.
It does not only cover images, but also input elements of type image, areas of an image map and embed- and object-elements.
Assuming that the attributes are accessibility supported, all these elements are semi-automated tested for the correct use of sufficient techniques for provision of a textual alternative. All circumstances, in which WCAG allows to omit a text alternative, such as for grouped images or as a part of a link, are considered. Additionally it is tested for the correct hiding of purely decorative content from assistive technologies and common failures like the use of placeholders or filenames as an alternative.
On most elements human evaluation is needed for the complete test.
The tests are semi-automated so automated tools can implement many of the 18 steps. The Auto-WCAG community is looking forward to see what developers can do with this great new test case.