Software Engineering: A Practitioner’s Approach,
6/e
Chapter 13
Software Testing Strategies
copyright © 1996, 2001, 2005
R.S. Pressman & Associates, Inc.
For University Use Only
May be reproduced ONLY for student use at the university level
when used in conjunction with Software Engineering: A Practitioner's Approach.
Any other reproduction or use is expressly prohibited.
These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with
permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 1
Software Testing
Testing is the process of exercising a
program with the specific intent of finding
errors prior to delivery to the end user.
These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with
permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 2
What Testing Shows
errors
requirements conformance
performance
an indication
of quality
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permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 3
Who Tests the Software?
developer independent tester
Understands the system Must learn about the system,
but, will test "gently" but, will attempt to break it
and, is driven by "delivery" and, is driven by quality
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permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 4
Testing Strategy
unit test integration
test
system validation
test test
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Testing Strategy
We begin by ‘testing-in-the-small’ and move toward
‘testing-in-the-large’
For conventional software
The module (component) is our initial focus
Integration of modules follows
For OO software
our focus when “testing in the small” changes from an
individual module (the conventional view) to an OO class that
encompasses attributes and operations and implies
communication and collaboration
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permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 6
Strategic Issues
State testing objectives explicitly.
Understand the users of the software and develop a profile for each user category.
Develop a testing plan that emphasizes “rapid cycle testing.”
Build “robust” software that is designed to test itself
Use effective formal technical reviews as a filter prior to testing
Conduct formal technical reviews to assess the test strategy and test cases themselves.
Develop a continuous improvement approach for the testing process.
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permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 7
Unit Testing
module
to be
tested
results
software
engineer
test cases
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permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 8
Unit Testing
module
to be
tested
interface
local data structures
boundary conditions
independent paths
error handling paths
test cases
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Unit Test Environment
driver
interface
local data structures
Module boundary conditions
independent paths
error handling paths
stub stub
test cases
RESULTS
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Integration Testing Strategies
Options:
• the “big bang” approach
• an incremental construction strategy
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Top Down Integration
A
top module is tested with
stubs
B F G
stubs are replaced one at
a time, "depth first"
C
as new modules are integrated,
some subset of tests is re-run
D E
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Bottom-Up Integration
A
B F G
drivers are replaced one at a
time, "depth first"
C
worker modules are grouped into
builds and integrated
D E
cluster
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Sandwich Testing
A
Top modules are
tested with stubs
B F G
Worker modules are grouped into
builds and integrated
D E
cluster
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Object-Oriented Testing
begins by evaluating the correctness and consistency of
the OOA and OOD models
testing strategy changes
the concept of the ‘unit’ broadens due to encapsulation
integration focuses on classes and their execution across a
‘thread’ or in the context of a usage scenario
validation uses conventional black box methods
test case design draws on conventional methods, but
also encompasses special features
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permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 15
Broadening the View of “Testing”
It can be argued that the review of OO analysis and
design models is especially useful because the
same semantic constructs (e.g., classes, attributes,
operations, messages) appear at the analysis,
design, and code level. Therefore, a problem in the
definition of class attributes that is uncovered
during analysis will circumvent side effects that
might occur if the problem were not discovered
until design or code (or even the next iteration of
analysis).
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permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 16
Testing the CRC Model
1. Revisit the CRC model and the object-relationship model.
2. Inspect the description of each CRC index card to determine if a
delegated responsibility is part of the collaborator’s definition.
3. Invert the connection to ensure that each collaborator that is
asked for service is receiving requests from a reasonable source.
4. Using the inverted connections examined in step 3, determine
whether other classes might be required or whether responsibilities
are properly grouped among the classes.
5. Determine whether widely requested responsibilities might be
combined into a single responsibility.
6. Steps 1 to 5 are applied iteratively to each class and through
each evolution of the OOA model.
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OOT Strategy
class testing is the equivalent of unit testing
operations within the class are tested
the state behavior of the class is examined
integration applied three different strategies
thread-based testing—integrates the set of classes
required to respond to one input or event
use-based testing—integrates the set of classes required
to respond to one use case
cluster testing—integrates the set of classes required to
demonstrate one collaboration
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permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 18
Smoke Testing
A common approach for creating “daily builds” for product
software
Smoke testing steps:
Software components that have been translated into code are
integrated into a “build.”
A build includes all data files, libraries, reusable modules, and engineered
components that are required to implement one or more product
functions.
A series of tests is designed to expose errors that will keep the build
from properly performing its function.
The intent should be to uncover “show stopper” errors that have the
highest likelihood of throwing the software project behind schedule.
The build is integrated with other builds and the entire product (in
its current form) is smoke tested daily.
The integration approach may be top down or bottom up.
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permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 19
High Order Testing
Validation testing
Focus is on software requirements
System testing
Focus is on system integration
Alpha/Beta testing
Focus is on customer usage
Recovery testing
forces the software to fail in a variety of ways and verifies that recovery is properly
performed
Security testing
verifies that protection mechanisms built into a system will, in fact, protect it from
improper penetration
Stress testing
executes a system in a manner that demands resources in abnormal quantity,
frequency, or volume
Performance Testing
test the run-time performance of software within the context of an integrated
system
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permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 20
Debugging:
A Diagnostic Process
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The Debugging Process
test cases
new test results
regression cases
tests suspected
causes
corrections
Debugging
identified
causes
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permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 22
Debugging Effort
time required
to diagnose the
time required symptom and
to correct the error determine the
and conduct cause
regression tests
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permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 23
Symptoms & Causes
symptom and cause may be
geographically separated
symptom may disappear when
another problem is fixed
cause may be due to a
combination of non-errors
cause may be due to a system
or compiler error
symptom cause may be due to
assumptions that everyone
cause believes
symptom may be intermittent
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permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 24
Consequences of Bugs
infectious
damage
catastrophic
extreme
serious
disturbing
annoying
mild
Bug Type
Bug Categories: function-related bugs,
system-related bugs, data bugs, coding bugs,
design bugs, documentation bugs, standards
violations, etc.
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permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 25
Debugging Techniques
brute force / testing
backtracking
induction
deduction
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Debugging: Final Thoughts
1. Don't run off half-cocked, think about the
symptom you're seeing.
2. Use tools (e.g., dynamic debugger) to gain
more insight.
3. If at an impasse, get help from someone else.
4. Be absolutely sure to conduct regression tests
when you do "fix" the bug.
These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with
permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 27
