Page 195 - DCAP405_SOFTWARE_ENGINEERING

Software Engineering

Notes like syntax errors does not detect them; the programmer must examine the output carefully
to detect them.
2. String Testing: Programs are invariably related to one another and interact in a total
system. Each program is tested to see whether it conforms to related programs in the
system. Each part of the system is tested against the entire module with both test and live
data before the whole system is ready to be tested.
3. System Testing: It is deigned to uncover weaknesses that were not found in earlier tests.
This includes forced system failure and validation of total system, as its user in the
operational environment will implement it. Under this testing, we take low volumes of
transactions based on live data. This volume is increased until the maximum level for each
transaction type is reached.
4. System Documentation: All design and test documentation should be well prepared and
kept in the library for future reference. The library is the central location for maintenance
of the new system.

5. User Acceptance Testing: Acceptance test has the objective of selling the user on the validity
and reliability of the system. It verifies that the system’s procedures operate to system
specifications and that the integrity of important data is maintained. Performance of an
acceptance test is actually the user’s show. User motivation is very important for the
successful performance of the system.

Self Assessment

Fill in the blanks:
13. The errors resulting from the interaction between ………………… are initially avoided.
14. The library is the central location for …………………… of the new system.

11.6 Debugging

The goal of testing is to identify errors in the program. The process of testing gives symptoms
of the presence of an error. After getting the symptom, we begin to investigate to localize the
error i.e. to find out the module causing the error. This section of code is then studied to find the
cause of the problem. This process is called debugging. Hence, debugging is the activity of
locating and correcting errors. It starts once a failure is detected.

11.6.1 Debugging Techniques

Although developers learn a lot about debugging from their experiences, but these are applied
in a trial and error manner. Debugging is not an easy process as per human psychology as error
removal requires the acceptance of error and an open mind willing to admit the error.
However, Pressman explains certain characteristics of bugs that can be useful for developing a
systematic approach towards debugging. These are:
The symptoms and cause may be geographically remote. That is, the symptom may appear in
one part of the program, while the cause may actually be located in other part. Highly coupled
programs can worsen this situation.
The symptom may disappear (temporarily) when another error is corrected.
The symptom may actually be caused by non errors (e.g. round off inaccuracies).

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