Transcript term paper_ASE - Louisiana Tech University

TESTING FOR THE
RELIABILITY OF A
SOFTWARE
SARAT CHANDRA YADAVALLI
CSC 532
TERM PAPER
Software Reliability Engineering Introduction
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Reliability for software is the probability of failure
free operation of a computer programme in a
specified environment for some specified interval
of natural units or time.
Software reliability engineering is the standard
that empowers the testers and developers to
simultaneously Ensure that product reliability meets user needs
 Speed the product to market faster
 Reduce product cost
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Software Reliability Engineering Process Diagram
1.List Associated
Systems
2. Develop Operational
Profiles
3.Engineer “Just Right”
Reliability
4. Prepare for Test
5.Execute Test
6.Guide Test
Requirements and
Architecture
Design and
Implementation
Test
Developing Operation Profiles
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Developing operational profiles will give
the information about how users will
employ the product being built
With the information given, both
development and test can be made more
realistic
Terminology
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Operation is a major system logical task,
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Operational Profile (OP) is simply the set
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OP can be represented in 2 ways:
of short duration which returns control to
the system when complete
of operations and their probabilities of
occurrence.
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Tabular representation
Graphical representation
Tabular Representation
Graphical Representation
Methodology
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Identify the initiators of operations
Choose between tabular or graphical
representation
Create an operations list for each initiator
and consolidate the results
Determine the occurrence rates of the
individual operations
Determine the occurrence probabilities
Preparing for Test
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The operational profile information is applied to
planning for efficient test.
Testing is the process of executing a program
with the intention of finding design errors in a
given environment.
Testing can only prove the incorrectness of the
software but not its correctness.
Concepts
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Run is a specified instance of an operation.
A run is characterized by the operation and its
input state
Input variable can be either direct or indirect
A test case is the partial specification of a run
through the naming of its direct input variables
and their values.
A run involves the execution of a test case.
Test procedure is a controller that sets up
environmental conditions and that invokes
randomly selected test cases at random times.
Direct and Indirect Input Variables for Process Fax
Call Operation of Fone Follower
Procedure
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Preparing test cases – It can be done by
simply recording in the field all the input
variables needed to initiate the runs that make
up the field execution of the software
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Preparing test procedures
Preparing test cases
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Estimating the number of new test cases
needed for the current release
Allocating the number of new test cases
among the systems to be tested
Allocating the number of new test cases
for each system among its new operations
Specify the new test cases
Adding the new test cases to the test
cases from previous releases.
Estimating the number of new test cases
needed for the current release
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Two factors must be taken into account:
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Time
Cost
Compute the number of test cases you have
time to prepare
Compute the number of test cases you can
afford to prepare
Take the minimum of these as the number of
test cases you will plan to prepare
Allocating the number of new test cases for
each system among its new operations
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Convert the graphical representation into tabular
Identify the rarely occurring critical new operations and
determine how many test cases to preassign to each
Determine the allocation probabilities for the other new
operations
Preassign one test case to each infrequent other new
operations
Assign the remaining test cases to the remaining other
new operations in accordance with the allocation
probabilities
Allocating the number of new test cases
among the systems to be tested
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Bulk of the test cases should be allocated to the
product itself
Majority of test cases are allocated to the
number of operations of the variation that occur
and do not occur for the product
Give particular weight to the differing operations
that have high occurrence probabilities
Allocation of Test cases to Operations of Fone Follower
Test cases Specification
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Select test cases within operations with equal
probability
Prepare test scripts for the selected test cases
When invoked, the test cases must convey the
operation they belong to and their direct input
variables to the system under test
Conclusion
“A laudable standard for software reliability
is Five 9’s - software which works
99.999% of the time”
We have discussed  The procedure to identify the operational
profiles used in defining the test cases.
 Procedure to prepare for test
References
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Text Book : Software Reliability Engineering – John D. Musa
http://members.aol.com/JohnDMusa/ARTweb.htm
Lyu, M. (Editor). 1996. Handbook of Software Reliability Engineering , ISBN 007-039400-8, McGraw-Hill, New York.
Tierney, J. 1997. SRE at Microsoft. Keynote speech at 8th International
Symposium On Software Reliability Engineering, November 1977, Albuquerque,
NM.
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Challenges in Software Reliability and Testing - Philip J. Boland, Department of
Statistics, National University of Ireland – Dublin.
Y. K. Malaiya and J. Denton “ Module Size Distribution and Defect Density,” Proc.
IEEE International Symposium on Software Reliability Engineering, Oct. 2000,
pp. 62-71
Operational Profile Specification, Test Case Generation, and Reliability Estimation
for Modules - D.M. Woit, Queen’s University, February 1994.
N. Li and Y.K. Malaiya “ROBUST: A Next Generation Software Reliability
Engineering Tool” Proc. IEEE Int. Symp. on Software Reliability Engineering, pp.
375-380, Oct. 1995.
Predicting Software Reliability from Testing Taking into Account Other Knowledge
about a Program - Antonia Bertolino (IStituto di Elaborazione della Informazione
del CNR, Pisa,Italy), Lorenzo Strigini (Centre for Software Reliability, City
University, London).