Testing Strategy - Software Testing: Testing Across the Entire Software Development Life Cycle - page 71

At the bottom along the horizontal axis, or x -axis, are the phases of the phased
development methodology (PDM) discussed in Chapter 2. The PDM starts with the
left-most column and proceeds left to right until implementation is complete. Each
subsequent column to the right represents the next phase of development.
At the left side along the vertical axis, or y -axis, are the software platform layers
necessary to operate a typical software application. The bottom-most row represents
the most basic software, the operating system, the software that “talks” directly to the
hardware. The next layer up is security software that restricts/allows access to all the
layer activities above it. The next layer up is data resources that provides fi le or da-
tabase management of data stored on fi xed or removable media. The next layer up is
connectivity that provides interchange of tasks and data among software components
located on different computers via networks. These connected computers can be lo-
cated physically in the same room, the next room, the next building, the next city, the
next state, the next country, or the next continent. Finally, the topmost row represents
the application under development that is the primary focus of the test plan. The exis-
tence of layers below the application under development gives us a strong indication
that planning testing just for the application under development may be insuffi cient.
So far, software testing may appear to be a simple choice among a number of
testing techniques whenever a tester sees the need. In fact, the strategy for using
these techniques is much more complex. The key to successful testing is to de-
velop the appropriate testing strategy for the application under development and the

Software testing

Static White

Performance

Black
X Too late to test

Software

Application

X

Connectivity
(private,

Data resources
(data

Security
(access,

Operating
System

Preliminary
investigation

Preliminary
construction

Final
constrnuction

Ship
or

Post-
implement

+ Analysis

Phased development

Figure 4.2

Testing strategy for the application under test