1. Instructor: Peter Clarke
CEN 5076 Software Testing
Fall 2005
Instructor: Peter Clarke

2. Course Introduction Syllabus Project STRG Questions
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3. Software Engineering
Software Engineering is the application of a systematic, disciplined, quantifiable approach to the development, operation and maintenance of software; that is, the application of engineering to software.  (5/5 points)
(Source: IEEE Std , IEEE Standard Glossary of Software Engineering Terminology)
CEN 5076 Class /29

4. Software Process
S/w Specification – requirements elicitation (func. & non-func.) and analysis.
S/w Development – systems design, detailed design (OO design), implementation.
S/w Validation – validating system against requirements (testing).
S/w Evolution – meet changing customer needs and error correction (maintenance).
CEN 5076 Class /29

5. Software Specification
Functionality of the software and constraints (non-functional requirements) on its operation must be defined.
Involves:
Requirements elicitation
the client and developers define the purpose of the system.
Output - description of the system in terms of actors and uses cases.
Actors include roles such as end users and other computers the system needs.
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6. Software Specification cont
Uses cases are general sequences of events that describe all possible actions between actor and the system for a given piece of functionality.
Analysis
Objective: produce a model of the system that is correct, complete, consistent, unambiguous, realistic, and verifiable.
Developers transform the use cases into an object model that completely describes the system.
Model is checked for ambiguities and inconsistencies.
Output: Object model annotated with attributes, operations, and associations.
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7. Software Development Software to meet the specification is produced.
System Design
Goals of the project are defined.
System decomposed into smaller subsystems (architectural model).
Strategies to build system identified e.g., h/w and s/w platform, data management, control flow, and security.
Output: model describing subsystem decomposition and system strategies.
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8. Software Development cont
Object Design
Bridges the gap between analysis model and the strategies identified in the system design.
Includes:
describing object and subsystem interfaces,
selecting off-the-shelf components,
Restructure object model to attain design goals e.g., extensibility, understandability, and required performance.
Output: detailed object model annotated with constraints and supporting documentation.
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9. Software Development cont
Implementation
Translation of the object model into source code.
No general process followed.
There are tools to assists the programmer such as CASE tools.
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10. Software Validation (or V&V)
Ensures the software does what the customer want, i.e., that the software conforms to its specification and meets the expectations of the customer.
Validation: ‘Are we building the right product?’
Ensures the software meets the expectations of the customer.
Verification: ‘Are we building the product right?’
Ensures the software conforms to the specification.
CEN 5076 Class /29

11. Software Validation (V&V) cont
Techniques
Software inspections (static): analyze and check system representations e.g., requirements documents, design diagrams, and program source code.
Software testing (dynamic): executing an implementation of the software with test data and examining the outputs against expected results.
V&V process establishes the existence of defects.
Debugging is a process that locates and corrects these defects.
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12. Software Evolution Software must evolve to meet the customer needs.
Software maintenance is the process of changing a system after it has been delivered. Reasons for maintenance:
to repair faults,
to adapt the software to a different operating environment, and
to add to or modify system’s functionality.
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13. Attributes of Good Software
Maintainability
Ease of changing the software to meets the changing needs of the customer.
Dependability
Reliability, security and safety.
Efficiency
Responsiveness, processing time, and memory usage.
Usability
Appropriate user interface and adequate documentation.
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14. Software Process Models
Waterfall
V-Model
Evolutionary
Boehm’s Spiral Model
Incremental
Unified Software Development Process Model (USDP)
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15. Waterfall Model (Royse 1970)
Requirements
Definition
System and
software design
Implementation
and unit testing
Integration and
system testing
Operation and
maintenance
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16. V-Model (Jensen & Tonies 1979)
Requirements
Specification
Acceptance
test
System design
System and
integration test
Detailed Design
Unit Test
Implementation
Horizontal lines denote
The information flow
between activities at the
same abstraction level.
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17. Evolutionary Model Concurrent activities Outline Description Initial
Version
Specification
Outline
Description
Intermediate
Versions
Development
Final
Version
Validation
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18. Boehm’s Spiral Model (Boehm 1987)
Evaluate alternatives,
identify & resolve risks
Design objectives,
alternatives, & constraints
Risk
analysis
Risk
analysis
Risk
analysis
Prototype 3
Prototype 2
Prototype 1
Not shown
in detail
Requirements
plan
Concept of
operation
S/w
Reqs.
Detailed
Design
Sys.
Product
Design
Development
Plan
Reqs.
Validation
Code
Integration
Plan
Design
Validation
Unit Test
Develop & verify
next level product
Integration
& Test
Acceptance
Test
Plan next phase
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19. Incremental Development (Mills et al. 1980)
Define outline
requirements
Assign requirements
to increments
Design system
architecture
Develop system
increment
Validate
increment
Integrate
increment
Validate
system
Final
system
System incomplete
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20. Unified Software Development Process
System
Development
Analysis model
Process is use
case driven!
specified by
realized by
Design model
Use case
model
distributed by
Deployment model
All models are related
through traceability
dependencies.
implemented by
Implementation
model
Requirements
captured as a
set of use cases.
verified by
Test model
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21. View of UDSP from a Testing Perspective
System
Development
Process is use
case driven!
Analysis model
specified by
Verified and/or
validate
realized by
Design model
Use case
model
Test model
distributed by
Deployment model
Requirements
captured as a
set of use cases.
implemented by
All models are related
through traceability
dependencies.
Implementation
model
CEN 5076 Class /29

22. What is software testing?
Software testing is the process of operating software under specified conditions, observing or recording the results and making an evaluation of some aspect of the software.
(IEEE/ANSI std )
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23. What is software testing?
Software testing is the process of uncovering evidence of defects in software systems.
A defect can be introduced during any phase of development or maintenance and results from one or more “bugs” – mistakes, misunderstandings, omissions or even misguided intent on the part of the developers.
(McGregor & Sykes 2001)
CEN 5076 Class /29

24. Testing Terminology
The following defns are taken from Binder 2000 and McGregor & Sykes 2001.
Failure – is the manifested inability of a system or component to perform a required function within specified limits e.g. abnormal termination, or unmet time and space constraints of the software.
A fault is missing or incorrect code.
An error is a human action that produces a fault.
CEN 5076 Class /29

25. Testing Terminology cont
A bug is an error or a fault.
Debugging is the process of tracking down the source of failures (errors and/or faults) and making repairs.
A test case specifies the pretest state of the component under test (CUT) and its environment, the test inputs and conditions, and the expected results.
A test point is a specific value for test case input state variables.
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26. Testing Terminology cont
A test suite is a collection of test cases, typically related to some testing goal or criterion.
A test driver is a class or utility program that applies test cases to a CUT.
A stub is a partial, temporary implementation of a component.
A test harness is a system of test drivers and other tools to support test execution.
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27. Testing Approach (McGregor & Sykes)
Analyze a little
Design a little
Code a little
Test what you can
Kinds of testing
Model testing
Class testing, replaces unit testing
Interaction testing, replaces integration testing
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28. Testing Approach (McGregor & Sykes)
Kinds of testing cont.
System (and subsystem) testing
Acceptance testing
Deployment/self testing
Motto: Test early, Test often, Test enough
CEN 5076 Class /29