Case Study 2: Why Six-Sigma Efforts Do Not Apply to Software

Read the case study titled, “Why Six-Sigma Efforts Do Not Apply to Software” located in Chapter 9 of the textbook (see attached) and consider a situation where you are working for a large software development company that is considering applying the Six-Sigma quality constraints to the software it produces. 

Write a five to six (5-6) page paper in which you:

1. Explain the Six-Sigma quality constraints and provide a justification as to why the software development company should consider it.   

2. Compare and contrast quality control processes for both hardware and software.

3. Examine the arguments presented in the case study and evaluate their applications to control the quality of software produced in the organization. 

4. Propose a testing strategy for a software development project that ensures high quality of the software delivered.

5. Describe the idiosyncrasies of software, and explain why software needs a different set of rules for testing and for quality control as opposed to those used in hardware.

6. Use at least three (3) quality resources in this assignment. Note: Wikipedia and similar Websites do not qualify as quality resources. 

Your assignment must follow these formatting requirements:

• Be typed, double spaced, using Times New Roman font (size 12), with one-inch margins on all sides; citations and references must follow APA or school-specific format. Check with your professor for any additional instructions.

• Include a cover page containing the title of the assignment, the student’s name, the professor’s name, the course title, and the date. The cover page and the reference page are not included in the required assignment page length.

The specific course learning outcomes associated with this assignment are:

• Compare and contrast testing techniques and concepts to include functional, performance, acceptance, and installation.

• Use technology and information resources to research issues in software engineering.

• Write clearly and concisely about advanced software engineering topics using proper writing mechanics and technical style conventions.

Grading for this assignment will be based on answer quality, logic / organization of the paper, and language and writing skills. Click here to view the rubric for this assignment.

Chapter 9
Testing the System

Shari L. Pfleeger
Joann M. Atlee

4th Edition

4th Edition

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

Contents
9.1 Principles of system testing
9.2 Function testing
9.3 Performance testing
9.4 Reliability, availability, and maintainability
9.5 Acceptance testing
9.6 Installation testing
9.7 Automated system testing
9.8 Test documentation
9.9 Testing safety-critical systems
9.10 Information systems example
9.11 Real-time example
9.12 What this chapter means for you

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

Chapter 9 Objectives
Function testing
Performance testing
Acceptance testing
Software reliability, availability, and maintainability
Installation testing
Test documentation
Testing safety-critical systems

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.1 Principles of System Testing
Source of Software Faults During Development

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.1 Principles of System Testing System Testing Process
Function testing: does the integrated system perform as promised by the requirements specification?
Performance testing: are the non-functional requirements met?
Acceptance testing: is the system what the customer expects?
Installation testing: does the system run at the customer site(s)?

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.1 Principles of System Testing
System Testing Process (continued)
Pictorial representation of steps in testing process

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.1 Principles of System Testing
Techniques Used in System Testing
Build or integration plan
Regression testing
Configuration management
versions and releases
production system vs. development system
deltas, separate files and conditional compilation
change control

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.1 Principles of System Testing
Build or Integration Plan
Define the subsystems (spins) to be tested
Describe how, where, when, and by whom the tests will be conducted

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.1 Principles of System Testing
Example of Build Plan for Telecommunication System
Spin Functions Test Start Test End
O Exchange 1 September 15 September
1 Area code 30 September 15 October
2 State/province/district 25 October 5 November
3 Country 10 November 20 November
4 International 1 December 15 December

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.1 Principles of System Testing
Example Number of Spins for Star Network
Spin 0: test the central computer’s general functions
Spin 1: test the central computer’s message-translation function
Spin 2: test the central computer’s message-assimilation function
Spin 3: test each outlying computer in the stand alone mode
Spin 4: test the outlying computer’s message-sending function
Spin 5: test the central computer’s message-receiving function

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.1 Principles of System Testing
Regression Testing
Identifies new faults that may have been introduced as current one are being corrected
Verifies a new version or release still performs the same functions in the same manner as an older version or release

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.1 Principles of System Testing
Regression Testing Steps
Inserting the new code
Testing functions known to be affected by the new code
Testing essential function of m to verify that they still work properly
Continuing function testing m + 1

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.1 Principles of System Testing
Configuration Management
Versions and releases
Production system vs. development system
Deltas, separate files and conditional compilation
Change control

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.1 Principles of System Testing
Test Team
Professional testers: organize and run the tests
Analysts: who created requirements
System designers: understand the proposed solution
Configuration management specialists: to help control fixes
Users: to evaluate issues that arise

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.2 Function Testing
Purpose and Roles
Compares the system’s actual performance with its requirements
Develops test cases based on the requirements document

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.2 Function Testing
Cause-and-Effect Graph
A Boolean graph reflecting logical relationships between inputs (causes), and the outputs (effects) or transformations (effects)

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.2 Function Testing
Notation for Cause-and-Effect Graph

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.2 Function Testing
Cause-and-Effect Graphs Example
INPUT: The syntax of the function is LEVEL(A,B) where A is the height in meters of the water behind the dam, and B is the number of centimeters of rain in the last 24-hour period
PROCESSING: The function calculates whether the water level is within a safe range, is too high, or is too low
OUTPUT: The screen shows one of the following messages
1. “LEVEL = SAFE” when the result is safe or low
2. “LEVEL = HIGH” when the result is high
3. “INVALID SYNTAX”
depending on the result of the calculation

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.2 Function Testing
Cause-and-Effect Graphs Example (Continued)
Causes
The first five characters of the command “LEVEL”
The command contains exactly two parameters separated by a comma and enclosed in parentheses
The parameters A and B are real numbers such that the water level is calculated to be LOW
The parameters A and B are real numbers such that the water level is calculated to be SAFE
The parameters A and B are real numbers such that the water level is calculated to be HIGH

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.2 Function Testing
Cause-and-Effect Graphs Example (Continued)
Effects
1. The message “LEVEL = SAFE” is displayed on the screen
2. The message “LEVEL = HIGH” is displayed on the screen
The message “INVALID SYNTAX” is printed out
Intermediate nodes
1. The command is syntactically valid
2. The operands are syntactically valid

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.2 Function Testing
Cause-and-Effect Graphs of LEVEL Function Example
Exactly one of a set of conditions can be invoked
At most one of a set of conditions can be invoked
At least one of a set of condition can be invoked
One effects masks the observance of another effect
Invocation of one effect requires the invocation of another

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.2 Function Testing
Decision Table for Cause-and-Effect Graph of LEVEL Function
Test 1 Test 2 Test 3 Test 4 Test 5
Cause 1 I I I S I
Cause 2 I I I X S
Cause 3 I S S X X
Cause 4 S I S X X
Cause 5 S S I X X
Effect 1 P P A A A
Effect 2 A A P A A
Effect 3 A A A P P

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.3 Performance Tests
Purpose and Roles
Used to examine
the calculation
the speed of response
the accuracy of the result
the accessibility of the data
Designed and administrated by the test team

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.3 Performance Tests
Types of Performance Tests
Stress tests
Volume tests
Configuration tests
Compatibility tests
Regression tests
Security tests
Timing tests
Environmental tests
Quality tests
Recovery tests
Maintenance tests
Documentation tests
Human factors (usability) tests

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.4 Reliability, Availability, and Maintainability
Definition
Software reliability: operating without failure under given condition for a given time interval
Software availability: operating successfully according to specification at a given point in time
Software maintainability: for a given condition of use, a maintenance activity can be carried out within stated time interval, procedures and resources

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.4 Reliability, Availability, and Maintainability
Different Level of Failure Severity
Catastrophic: causes death or system loss
Critical: causes severe injury or major system damage
Marginal: causes minor injury or minor system damage
Minor: causes no injury or system damage

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.4 Reliability, Availability, and Maintainability
Failure Data
Table of the execution time (in seconds) between successive failures of a command-and-control system

Interfailure Times (Read left to right, in rows)
3 30 113 81 115 9 2 91 112 15
138 50 77 24 108 88 670 120 26 114
325 55 242 68 422 180 10 1146 600 15
36 55 242 68 227 65 176 58 457 300
97 263 452 255 197 193 6 79 816 1351
148 21 233 134 357 193 236 31 369 748
0 232 330 365 1222 543 10 16 529 379
44 129 810 290 300 529 281 160 828 1011
445 296 1755 1064 1783 860 983 707 33 868
724 2323 2930 1461 843 12 261 1800 865 1435
30 143 108 0 3110 1247 943 700 875 245
729 1897 447 386 446 122 990 948 1082 22
75 482 5509 100 10 1071 371 790 6150 3321
1045 648 5485 1160 1864 4116

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.4 Reliability, Availability, and Maintainability
Failure Data (Continued)
Graph of failure data from previous table

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.4 Reliability, Availability, and Maintainability
Uncertainty Inherent from Failure Data
Type-1 uncertainty: how the system will be used
Type-2 uncertainty: lack of knowledge about the effect of fault removal

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.4 Reliability, Availability, and Maintainability
Measuring Reliability, Availability, and Maintainability
Mean time to failure (MTTF)
Mean time to repair (MTTR)
Mean time between failures (MTBF)
MTBF = MTTF + MTTR
Reliability R = MTTF/(1+MTTF)
Availability A = MTBF (1+MTBF)
Maintainability M = 1/(1+MTTR)

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.4 Reliability, Availability, and Maintainability
Reliability Stability and Growth
Probability density function f or time t, f (t): when the software is likely to fail
Distribution function: the probability of failure
F(t) = ∫ f (t) dt
Reliability Function: the probability that the software will function properly until time t
R(t) = 1- F(t)

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.4 Reliability, Availability, and Maintainability
Uniformity Density Function
Uniform in the interval from t=0..86,400 because the function takes the same value in that interval

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.4 Reliability, Availability, and Maintainability
Sidebar 9.4 Difference Between Hardware and Software Reliability
Complex hardware fails when a component breaks and no longer functions as specified
Software faults can exist in a product for long time, activated only when certain conditions exist that transform the fault into a failure

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.4 Reliability, Availability, and Maintainability
Reliability Prediction
Predicting next failure times from past history

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.4 Reliability, Availability, and Maintainability
Elements of a Prediction System
A prediction model: gives a complete probability specification of the stochastic process
An inference procedure: for unknown parameters of the model based on values of t₁, t₂, …, ti-1
A prediction procedure: combines the model and inference procedure to make predictions about future failure behavior

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.4 Reliability, Availability, and Maintainability
Reliability Model
The Jelinski-Moranda model: assumes
no type-2 uncertainty
corrections are perfect
fixing any fault contributes equally to improving the reliability
The Littlewood model
treats each corrected fault’s contribution to reliability as independent variable
uses two source of uncertainty

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.4 Reliability, Availability, and Maintainability
Successive Failure Times for Jelinski-Moranda
I Mean Time to ith failure Simulated Time to ith Failure
1 22 11
2 24 41
3 26 13
4 28 4
5 30 30
6 33 77
7 37 11
8 42 64
9 48 54
10 56 34
11 67 183
12 83 83
13 111 17
14 167 190
15 333 436

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.5 Acceptance Tests
Purpose and Roles
Enable the customers and users to determine if the built system meets their needs and expectations
Written, conducted and evaluated by the customers

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.5 Acceptance Tests
Types of Acceptance Tests
Pilot test: install on experimental basis
Alpha test: in-house test
Beta test: customer pilot
Parallel testing: new system operates in parallel with old system

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.4 Reliability, Availability, and Maintainability
Result of Acceptance Tests
List of requirements
are not satisfied
must be deleted
must be revised
must be added

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.6 Installation Testing
Before the testing
Configure the system
Attach proper number and kind of devices
Establish communication with other system
The testing
Regression tests: to verify that the system has been installed properly and works

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.7 Automated System Testing
Simulator
Presents to a system all the characteristics of a device or system without actually having the device or system available
Looks like other systems with which the test system must interface
Provides the necessary information for testing without duplication the entire other system

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.8 Test Documentation
Test plan: describes system and plan for exercising all functions and characteristics
Test specification and evaluation: details each test and defines criteria for evaluating each feature
Test description: test data and procedures for each test
Test analysis report: results of each test

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.8 Test Documentation
Documents Produced During Testing

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.8 Test Documentation
Test Plan
The plan begins by stating its objectives, which should
guide the management of testing
guide the technical effort required during testing
establish test planning and scheduling
explain the nature and extent of each test
explain how the test will completely evaluate system function and performance
document test input, specific test procedures, and expected outcomes

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.8 Test Documentation
Parts of a Test Plan

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.8 Testing Documentation
Test-Requirement Correspondence Chart

Test Requirement 2.4.1:
Generate and
Maintain Database Requirement 2.4.2:
Selectively Retrieve
Data Requirement 2.4.3:
Produced Specialized
Reports
1. Add new record X
2. Add field X
3. Change field X
4. Delete record X
5. Delete field X
6. Create index X
Retrieve record with a requested
7. Cell number X
8. Water height X
9. Canopy height X
10. Ground cover X
11, Percolation rate X
12. Print full database X
13. Print directory X
14. Print keywords X
15. Print simulation summary X

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.8 Test Documentation
Sidebar 9.8 Measuring Test Effectiveness and Efficiency
Test effectiveness can be measured by dividing the number of faults found in a given test by the total number of faults found
Test efficiency is computed by dividing the number of faults found in testing by the effort needed to perform testing

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.8 Test Documentation
Test Description
Including
the means of control
the data
the procedures

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.8 Test Documentation
Test Description Example
INPUT DATA:
Input data are to be provided by the LIST program. The program generates randomly a list of N words of alphanumeric characters; each word is of length M. The program is invoked by calling
RUN LIST(N,M)
in your test driver. The output is placed in global data area LISTBUF. The test datasets to be used for this test are as follows:
Case 1: Use LIST with N=5, M=5
Case 2: Use LIST with N=10, M=5
Case 3: Use LIST with N=15, M=5
Case 4: Use LIST with N=50, M=10
Case 5: Use LIST with N=100, M=10
Case 6: Use LIST with N=150, M=10
INPUT COMMANDS:
The SORT routine is invoked by using the command
RUN SORT (INBUF,OUTBUF) or
RUN SORT (INBUF)
OUTPUT DATA:
If two parameters are used, the sorted list is placed in OUTBUF. Otherwise, it is placed in INBUF.
SYSTEM MESSAGES:
During the sorting process, the following message is displayed:
“Sorting … please wait …”
Upon completion, SORT displays the following message on the screen:
“Sorting completed”
To halt or terminate the test before the completion message is displayed, press CONTROL-C on the keyboard.

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.8 Test Documentation
Test Script for Testing The “change field”
Step N: Press function key 4: Access data file.
Step N+1: Screen will ask for the name of the date file.
Type ‘sys:test.txt’
Step N+2: Menu will appear, reading
* delete file
* modify file
* rename file
Place cursor next to ‘modify file’ and press RETURN key.
Step N+3: Screen will ask for record number. Type ‘4017’.
Step N+4: Screen will fill with data fields for record 4017:
Record number: 4017 X: 0042 Y: 0036
Soil type: clay Percolation: 4 mtrs/hr
Vegetation: kudzu Canopy height: 25 mtrs
Water table: 12 mtrs Construct: outhouse
Maintenance code: 3T/4F/9R
Step N+5: Press function key 9: modify
Step N+6: Entries on screen will be highlighted. Move cursor to VEGETATION field. Type ‘grass’ over ‘kudzu’ and press RETURN key.
Step N+7: Entries on screen will no longer be highlighted.
VEGETATION field should now read ‘grass’.
Step N+8: Press function key 16: Return to previous screen.
Step N+9: Menu will appear, reading
* delete file
* modify file
* rename file
To verify that the modification has been recorded,place cursor next to ‘modify file’ and press RETURN key.
Step N+10: Screen will ask for record number. Type ‘4017’.
Step N+11: Screen will fill with data fields for record 4017:
Record number: 4017 X: 0042 Y: 0036
Soil type: clay Percolation: 4 mtrs/hr
Vegetation: grass Canopy height: 25 mtrs
Water table: 12 mtrs Construct: outhouse
Maintenance code: 3T/4F/9R

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.8 Test Documentation
Test Analysis Report
Documents the result of test
Provides information needed to duplicate the failure and to locate and fix the source of the problem
Provides information necessary to determine if the project is complete
Establish confidence in the system’s performance

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.8 Test Documentation
Problem Report Forms
Location: Where did the problem occur?
Timing: When did it occur?
Symptom: What was observed?
End result: What were the consequences?
Mechanism: How did it occur?
Cause: Why did it occur?
Severity: How much was the user or business affected?
Cost: How much did it cost?

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.10 Information Systems Example
The Piccadilly System
Many variables, many different test cases to consider
An automated testing tool may be useful

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.10 Information Systems Example
Things to Consider in Selecting a Test Tool
Capability
Reliability
Capacity
Learnability
Operability
Performance
Compatibility
Nonintrusiveness

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.10 Information Systems Example
Sidebar 9.13 Why Six-Sigma Efforts Do Not Apply to Software
A six-sigma quality constraint says that in a billion parts, we can expect only 3.4 to be outside the acceptable range
It is not apply to software because
People are variable, the software process inherently contains a large degree of uncontrollable variation
Software either conforms or it does not, there are no degree of conformance
Software is not the result of a mass-production process

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.11 Real-Time Example
Ariane-5 Failure
Simulation might help preventing the failure
Could have generated signals related to predicted flight parameters while turntable provided angular movement

Pfleeger and Atlee, Software Engineering: Theory and Practice
Chapter 9.*

9.12 What This Chapter Means for You
Should anticipate testing from the very beginning of the system life cycle
Should think about system functions during requirement analysis
Should use fault-tree analysis, failure modes and effect analysis during design
Should build safety case during design and code reviews
Should consider all possible test cases during testing