Usability testing shall use a model of the software/system that specifies its usability requirements including any required usability design standards to which the software/system must conform. Usability requirements shall specify the usability goals for the system. Usability goals will be based on system goals (the reason for having the system, the difference it is to make for the organisation or individual, its purpose and the tasks it will aid), and the contexts of use for the software/system (who is to use the system and the environment in which it is to be used, user characteristics and user tasks). Usability goals will be defined for the effectiveness, efficiency and satisfaction for specified users to achieve specified goals in one or more specified contexts of use.
Testing techniques shall be selected that can be used to exercise a certain usability characteristic (e.g. understandability, operability or task effectiveness). Test cases shall subsequently be defined to determine whether the usability requirements are met. For each test case the following will be defined:
§ The input to the system or the action to be taken by the user or both if the test covers both the software and non-software parts of the system/task
§ The usability requirement(s) exercised
§ The expected outcome (can be either a change to the state of the system/software, an output from the system/software or a change in the state of the user. For example if the usability requirement is for the user to have learnt something the test is checking that this particular user has learnt that thing.)
More than one usability requirement may by exercised by a single test case. The test design shall be documented.
Usability testing shall be measured as the percentage exercised of the total specified usability requirements.