Accessibility testing tools such the WAVE and HiSoftware Compliance Sheriff can provide efficiencies that cannot be equaled. They can help detect if a web page is inaccessible and identify issues that might otherwise be time consuming or difficult to identify manually. They will catch things such as missing alt text, form controls without labels, and contrast errors. They can catch those types of errors much better than a person can and those kind of errors are very important to accessibility. Automated testing tools excel when the decision logic can be boiled down to a simple yes or no answer, and that answer can be determined using machine accessible data. Automated tools can quickly locate a lot of obvious problems, reducing the initial time one needs to spend looking over a page for problems.
Passing automated accessibility testing does not mean that a Web site or application is accessible. The greatest danger with automated accessibility tools is the assumption that they can somehow replace human involvement in improving accessibility. Use accessibility tools, but remember they are only one part of the toolkit. Sole reliance on them as sole indicators of accessibility compliance gives a false sense of security. In addition they may inaccurately portray a site or app as being fully accessible to people with disabilities when in fact problems exist. Evaluating Web site accessibility is an art not a science - it can't be reduce to running a site through an automated tool.
A level of human interaction will always be required to assure that content is fully accessible. An automated tool is not a complete solution. For example:
- Logical flow or logical meaning of content can only be assured through a manual review.
- Ensuring that the tab order is logical and follows an expected path and that the current input focus is visible to the end user all require human interaction.
- Keyboard access can only be confirmed by a live tester taking the steps to evaluate those functions.
- Verifying that text alternatives are meaningful can only be accomplished by manual review.
Therefore you can't stop at automated testing. To be effective, accessibility checkers should form part of a wider process. A comprehensive approach, including testing by people with different abilities and skills as well as evaluation by individuals knowledgeable in the field of accessible Web design is best. While automated tools are not a complete solution they are a necessary part of any serious accessibility evaluation effort.
In addition, a limitation of the WAVE is that it will test one single page at a time and not a whole site.