Testing Complex Applications - Software Testing: Testing Across the Entire Software Development Life Cycle - page 247

Figure 14.12 Tier 2 identification for a complex n-tier application

Application components that seem to provide the business functionality lay-
ers on the other side of the web services are “lassoed” last as seen in Figure 14.14.
These components and their activities will be included in the tier 4 test strategy
chessboard.
From this tier identifi cation, we develop the individual tier testing strategy
chessboards. Then we stack the chessboards starting with tier 4, then tier 3, then tier
2, then tier 1 with tier-to-tier connectivity layers in between each pair of tiers.
Finally, we review the overall testing strategy with the development team to
confi rm that the strategy represents the most logical testing progression of the tiers
and their components. It is possible that this review may reveal some alternate ap-
proaches to the overall development that can take advantage of the test results as
they are completed. It is equally possible that one or more of the tier components
were not correctly described to the testers or some component activities have been
redefi ned. The design changes probably imply test planning changes. The good news
is that you have been able to address these development changes very early in your
test planning, minimizing disruption and rewriting of test cases later in the “throes
of battle.”