Lecture 20 software testing (2)

Introduction to Software Engineering
Muhammad Nasir
Software Testing Strategies (2)
m.nasir@iiu.edu.pk

Agenda
 Integration Testing
 Validation Testing
 System Testing
 Recovery Testing
 Security Testing
 Stress Testing
 Performance Testing
 Deployment Testing

Integration Testing
 Integration testing is a systematic
technique for constructing the program
structure while at the same time conducting
tests to uncover errors associated with
interfacing.
 The objective is to take unit tested
components and build a program structure
that has been dictated by design.

Non-Incremental Approach
 There is often a tendency to attempt
non-incremental integration; that is,
to construct the program using a "big
bang" approach.
 A set of errors is encountered.

 Correction is difficult because isolation
of causes is complicated by the large
size of the entire program.
 Once these errors are corrected, new
ones appear and the process continues
in a seemingly endless loop.

(Big Bang)

Incremental Approach
 Incremental integration is the exact
opposite of the big bang approach.
 The program is constructed and tested
in small increments, where errors are
easier to isolate and correct;

Validation Testing
 Validation testing begins at the end of
integration testing, when the software is
completely assembled as a package.
 Validation Testing Includes
 Configuration Testing – Checking all the
elements in the package and their version
 Alpha Testing – Controlled Testing by user at
developer site
 Beta Testing – Open Testing a User site

System Testing
 Software is only one element of a larger
computer-based system
 Ultimately, software is incorporated with
other system elements (e.g., hardware,
people, information)
 System testing is actually a series of
different tests whose primary purpose is to
fully exercise the computer-based system.

System Testing
 System Testing Includes;
 Recovery Testing
 Security Testing
 Stress Testing
 Performance Testing
 Deployment Testing

Recovery Testing
 Recovery testing is a system test that forces
the software to fail in a variety of ways and
verifies that recovery is properly performed.
 If recovery is automatic (performed by the
system itself), re-initialization, check-pointing
mechanisms, data recovery, and restart are
evaluated for correctness.
 If recovery requires human intervention, that
is mean-time-to-repair (MTTR) is evaluated
to determine whether it is within acceptable
limits.

Security Testing
 Security testing attempts to verify that
protection mechanisms built into a system
will, in fact, protect it from improper break
through .
 During security testing, the tester plays the
role(s) of the individual who desires to break
through the system.
 Given enough time and resources, good
security testing will ultimately penetrate a
system.

Security Testing
 The tester may attempt to acquire passwords;
 May attack the system with custom software
designed to break down any defenses that have
been constructed;
 May overwhelm the system, thereby denying service
to others;
 May purposely cause system errors, hoping to
penetrate during recovery; may browse through
insecure data, hoping to find the key to system entry.

Stress Testing
 Stress testing executes a system in a manner that demands
resources in abnormal quantity, frequency, or volume.
For example,
1. special tests may be designed that generate ten interrupts per
second
2. Input data rates may be increased by an order of magnitude to
determine how input functions will respond
3. Test cases that require maximum memory or other resources
are executed
 A variation of stress testing is a technique called sensitivity
testing

Performance Testing
 Performance testing occurs throughout all
steps in the testing process.
 Even at the unit level, the performance of an
individual module may be assessed as white-box
tests are conducted.
 Performance tests are often coupled with
stress testing and usually require both
hardware and software instrumentation
 It is often necessary to measure resource
utilization (e.g., processor cycles).

Deployment Testing
 In many cases, software must execute on a
variety of platforms and under more than one
operating system environment.
 In addition, deployment testing examines all
installation procedures and specialized
installation software that will be used by
customers,
 and all documentation that will be used to
introduce the software to end users

Deployment Testing
 A more thorough deployment test
might encompass combinations of
Web browsers with various operating
systems (e.g., Linux, Mac OS,
Windows).
 Because security is a major issue, a
complete set of security tests would be
integrated with the deployment test.

The End
 Thanks for listening
 Questions would be appreciated.

Lecture 20 software testing (2)

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