Core considerations - Unit testing
Developers can quickly improve products by the simple act of unit testing for accessibility. Run an automated tool to capture detectable violations. Check zoom and reflow of the content. Then before you check-in your code, put your mouse aside and make sure you can fully operate the components with a keyboard. Checking as you go with a keyboard is the easiest way to improve accessibility and reduce future effort and risk.
Incorporate and run verification tools
IBM has taken several steps to ease accessibility testing and improve automation. As developers, you can manually run the Accessibility Checker for Chrome or Firefox from your browser or IDE. You can view issues by element or by accessibility requirement. You can also add accessibility into your continuous integration testing. Ensuring that checkers run without violations helps developers meet 4.1.1 Parsing and 4.1.2 Name, Role, Value.
Check that the content can be zoomed
Developers can quickly validate whether they can adjust the content size while remaining accessible. Use the browser to zoom the content to 200% and ensure that text still fits in its containers and nothing odd happens to positioning of controls and other elements. Then keep increasing up to 400%. Ensure that the breakpoints match the design specifications. All content should be visible without requiring horizontal scrolling.
Confirm component keyboard interaction
Every component must be keyboard operable. As developers confirm the success of the keyboard operation (which should be indicated in the wireframes), they also confirm they never become stuck in a keyboard trap. Keys used for interaction are Escape, Space bar, Enter, Home, End, Page Up, Page Down, and the arrow keys. Complex interactions may also use modifier keys such as Shift, Ctrl, and Alt. IBM recommends the ARIA authoring practices as a model for keyboard interaction. Developers can also use this interaction test to confirm that visual indicators for states (selected/unselected, expanded/collapsed) align with the UX design.
Check tab order
When testing a larger portion of the content, repeatedly press the Tab key to traverse all interactive elements or groups of elements. This allows you to reconfirm several things:
*Acceptable behavior for complex components and groups of widgets, such a menus or toolbars, is to use a single tab stop, with arrow key navigation between the items in the group or complex component.