RE: [usage-centered] task cases as acceptance tests?
> I'm in a situation where I need to produce acceptance tests forGood question. We have used task cases to generate inspection scenarios and
> existing applications. I'm burdened with a little understanding of
> usage-centered design, and now have a hard time looking at any
> application without quickly backing up, trying to understand who's
> using the app - their role - and quickly writing a task case for what
> they're trying to accomplish, then comparing this task case to the
> application I'm seeing. Basically I'm using the task case as the
> foundation/starting block for acceptance testing.
> It works for me to just use the task case as an acceptance test.
> Obviously I need to convert the generalities in the task case to
> specifics as I manually execute a test. I'm having a hard time
> getting other folks to make this leap. The temptation is to write a
> long complex test case, that's time consuming to write, and brittle.
> Minor changes in the application result in changes to the acceptance
> test - which often don't get done. The result is acceptance tests
> that don't square with the acceptable product.
> Do I have a question here? Maybe. Does anyone, Larry and Lucy
> included, have experience using usage-centered design methods in
> support of acceptance testing. What components of ucd lend
> themselves well to acceptance testing? What is inapropriate to use?
usability test scenarios on a couple of projects. We build each scenario or
test cases as the enactment of a cluster of closely connected task cases
based on (extension, inclusion, precedence, etc.). Because test cases and
inspection/test scenarios are concrete (referring to an actual interface and
specifying actual expected behavior), they are necessarily more sensitive to
design changes. Tests must specify correct results ("the user clicks New or
the Create Project tool, which launches the new project screen with default
values for name and type; opening the project view tab from the new project
screen should display an empty list of project elements..."). If the
architecture, functionality, or method of navigation changes, the text
case/scenario does have to be rewritten. I don't know of a simple or elegant
way around this.
However, traceability and maintainability can be improved if each test
case/scenario is linked to the cluster of task cases from which it has been
generated. Of course, these in turn are linked to the interaction contexts
that support them. A change in a task or the interaction context that
supports it can then be traced back to the test case/scenario that validates
that part of the system and the test/scenario can be rewritten and "rerun."
Furthermore, the number of task cases combined into a test case/scenario can
be limited, so that test cases/scenarios are kept relatively compact.
Furthermore, guided by the task model, you can avoid (most) duplication in
which one task case is built into a number of different test cases. This
should help avoid massive rewriting and retesting when some small thing
--Larry Constantine | Director of Research & Development
Constantine & Lockwood, Ltd. | www.foruse.com
Winners of the Performance-Centered Design Competition 2001