Off the-shelf components (cots)

1. Testing off the shelf Components
Dr. Himanshu Hora
SRMS College of Engineering & Technology
Bareilly (INDIA)

2. Outline :
 Introduction to COTS components
 Advantages of COTS components
 Challenges in testing COTS components
 Testing types of COTS components
 References

3. Introduction:
What is Component Based Software Engineering (CBSE)?
 Idea to develop software systems by selecting appropriate
off-the-shelf components and then assemble them with a
well-defined software architecture.
 CBSE has three major functions:
Developing software from prefabricated, reusable
parts.
The ability to use those parts in other applications.
Easily maintaining and customizing those parts to
produce new functions and features.

4. What is a COTS component:
What is a Commercial Off the shelf (COTS) component:
 Independent and replaceable part of a system that fulfills a
clear function
 Works in the context of a well defined architecture
 A component communicates with other components by its
interfaces
 Developed by different developers, using different
languages and different platforms

5. Contd….
Component 1
Component
repository
select
Component 2
Software system
Component n
assemble

6. Advantages of COTS:
Development cost is reduced
Development time is reduced
Complex systems can be built by reusing pre-existing
components
Testing effort is reduced

7. Testing Components: Challenges
 COTS is a Black Box
 Lack of Functional and Technical Requirements
 The Level of Quality is Unknown
 Unknown Development Processes and Methods
 Compatibility Issues
 Uncertain Upgrade Schedules and Quality
 Difficulty in Regression Testing and Test Automation
 Interoperability and Integration Issues

8. Testing techniques:
 Black-box component testing
 System-level fault injection
 Operational system testing
 Software Wrapping
 Interface propagation Analysis

9. Black box Testing:
 To understand the behavior of a component, various
inputs are executed and outputs are analyzed
 To catch all types of errors all possible combinations of
input values should be executed
 To make testing feasible, test cases are selected
randomly from test case space

10. Contd….

11. Fault Injection:
request
Fault
simulation
tool
Erroneous or
malicious input
Component
Fault
simulation
tool
Exceptions, No
response

12. Contd….
 A technique for improving the coverage of a test by
introducing faults to test code paths
 Fault propagate through to an observable failure follows
a well defined cycle
 When executed, a fault may cause an error, which is an
invalid state within a system boundary
 An error may cause further errors within the system
boundary
 Each new error acts as a fault
 When error states are observed at the system boundary
they are termed failures
 This is termed the fault-error-failure cycle

13. Contd….

16. Operational system testing:
 complements system-level fault injection
 System is operated with random inputs (valid and invalid
inputs)
 Provides more accurate assessment of COTS quality
 A key operational testing feature is error detection,
which ensures correct functional implementation
 Operational testing allows component interaction

17. Software Wrapping :
Input wrapper
Input
Output wrapper
Component
output

18. Contd….
 Wrapper: generally refers to a type of packaging, such as
a flat sheet to enclose an object
 It is a piece of code that one builds to isolate the
underlying components from other components of the
system
 Glue: A glue component provides the functionality to
combine different components

19. Interface propagation Analysis:
COTS
Component 1
Fault Injector
 Modify input, call correct method.
 Call correct method, modify output.
COTS
Component 2

20. Contd….
 Interface Propagation Analysis is used by injecting faults
at one component
 This is done at component integration level
 A known faulty input is injected using fault injector into
the system
 Components effected by this input are observed (how
they handle the faulty input)

21. Refrences:
 http://www.cigital.com/presentations/zurich98/sld087.h
tm
 http://my.safaribooksonline.com/book/softwareengineering-and-development/softwaretesting/0201325640/testing-interactions/ch06lev1sec4
 http://my.safaribooksonline.com/book/softwareengineering-and-development/softwaretesting/0201325640/testing-interactions/ch06lev1sec4

22. Thank You
Dr. Himanshu Hora
SRMS College of Engineering & Technology
Bareilly (INDIA)