What is Alt -text?
Alt-text is an attribute on web elements that is used by screen-readers to assist those with disabilities by providing a description of that element. It is an inbuilt feature in Power BI used to describe the visual to those that are visually impaired. Microsoft recommends that report builders should alt text to every object that conveys meaningful information on a report.
Why does PowerTester need the visual alt-text?
PowerTester requires a unique reference for each visual on a page of a report, alt-text is used for this purpose. It is used by PowerTester to identify the target visual in the page of the report. Therefore for each Power BI report page the alt-text must be unique.
How to enter Alt-text in Power BI?
You can add alt-text to Power BI reports by opening a report in either Power BI Desktop or the web app Then select the visual and in the Visualizations pane, select the Format section, expand General, scroll to the bottom, and fill in the Alt Text textbox. The Alt Text textbox has a limit of 250 characters.
For more information view the official Microsoft article.