teSting eStimation 181
Total Function points 5 [UFPB 1 ADD 1 CHGA]2[CHGB2DELFP]
UFPB: Function points previously counted before enhancement.
ADD: Newly added functionality which leads to new function points after
enhancements.
CHGA: Changed function points counted after enhancements.
CHGB: Changed function points before enhancements.
DELFP: Deleted function points.
(a) can you explain hoW tpa Works?
There are three main elements which determine estimates for black box
testing: size, test strategy, and productivity. Using all three elements we can
determine the estimate for black box testing for a given project. Let’s take a
look at these elements.
Size: The most important aspect of estimating is definitely the size of the
project. The size of a project is mainly defined by the number of function
points. But a function point fails or pays the least attention to the following
factors:
Complexity: Complexity defines how many conditions exist
in function points identified during a project. More conditions
means more test cases which means more testing estimates.
For instance, the following is an application which takes the
customer name from the end user. If the customer name is
greater than 20 characters then the application should give
an error. So for this case there will be one test case. But let’s
say the end user also puts one more condition that if the user
inputs any invalid character then the application should give
an error. Because there is one more extra condition in the
project the complexity has increased, which also means that
we need to test two cases. The following illustrates this figure.
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182 Software teSting interview QueStionS
Interfacing: How much does one function affect the other
part of the system? If a function is modified then accordingly
the other systems have to be tested as one function always
impacts another.
Uniformity: How reusable is the application? It is important
to consider how many similar structured functions exist in
the system. It is important to consider the extent to which the
system allows testing with slight modifications.
Test strategy: Every project has certain requirements. The importance of all
these requirements also affects testing estimates. Any requirement importance
is from two perspectives: one is the user importance and the other is the user
usage. Depending on these two characteristics a requirement rating can be
generated and a strategy can be chalked out accordingly, which also means
that estimates vary accordingly.
Productivity: This is one more important aspect to be considered while
estimating black box testing. Productivity depends on many aspects. For
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FIGURE 159 Complexity
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