How to verify and validate a software in software engineering

1. WHAT IS VERIFICATION AND VALIDATION OF SOFTWARE ??
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SUBMITTED BY : Group 2
Adeel Kamran 03
Ali Raza Sheikh 04
Ali Raza 07
Sir Shafiq Shb
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2. Software verification
Definition:
“The process of evaluating software to determine whether the products of a given development
phase satisfy the conditions imposed at the start of that phase.”
Articles:
• Fault – wrong or missing function in the code.
• Failure – the manifestation of a fault during execution. The software was not effective. It does
not do "what" it is supposed to do.
• Malfunction – according to its specification the system does not meet its specified functionality.
The software was not efficient (it took too many resources such as CPU cycles, it used too much
memory, performed too many I/O operations, etc.), it was not usable, it was not reliable, etc. It
does not do something "how" it is supposed to do it.
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3. Types of Verification:
Verification is static type of s/w testing. It means code is not executed. The product
is evaluated by going through the code.
There are three types of verification.
1) Walk through
2) Inspection
3) Reviews
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4. Walk through:
 This is the informal type of software verification.
 Initiated by the author of the s/w product to a colleague for assistance in
locating defects or suggestions for improvements.
 They are usually unplanned.
 Author explains the product.
 Colleague comes out with observations.
 Author notes down relevant points and takes corrective actions.
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5. Inspection:
Word-by-word checking of a software product.
Intentions:
- Locating defects.
- Confirming traceability of relevant requirements.
- Checking for conformance to relevant standards and conventions.
Inspections are more formal than walkthroughs. It involves 5 major roles
-Author: person who originally created the work product.
- Moderator: Person responsible to ensure the discussions proceed on the productive lines.
- Reader: Person responsible for reading aloud small logical units of the work product
- Recorder: Person who records/documents all the defects that arise from the inspection team.
- Inspector: All of the inspection team members who analyze and detect the defects within the
work
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6. Reviews
 Subsequent examination of a product for the purpose of monitoring earlier changes.
 One or more persons check the changed documents or data to determine if the
changes are correct.
 analysis undertaken at a fixed point in time to determine the degree to which stated
objectives have been reached.
Division of verification:
- Inspection: Typical walkthroughs, software reviews, technical reviews, and
formal inspections.
- Analysis: It is about estimation of execution times and estimation of system
resources.
- Testing: Verification phase is about white box testing. Techniques include
statement coverage, condition coverage, and decision coverage.
- Demonstration: It is about black box testing. Techniques include error
guessing, boundary-value analysis, and equivalence partitioning.
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7. Four levels of verification:
1) Component Testing:
Verifying the design implementation for one software element like unit / module or a group of
software elements
2) Integration Testing:
Testing with orderly progression which involves the integration of various software and or
hardware elements together and tested. It continuous until the complete system has been
integrated.
3) System Testing:
A type of testing which tests integrated software and hardware system verification whether the
system meets the specified requirements.
4) Acceptance Testing:
A testing process that determines whether a system satisfies the acceptance criterion and for
enabling the customer for determining whether or not to accept the system.
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8. Software Validation
 Validation: Are we building the right product?
In simple terms, software verification is:
"Assuming we should build X, does our software
achieve its goals without any bugs or gaps?"
On the other hand, software validation is:
"Was X what we should have built? Does X
meet the high level requirements?"
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9. Software Validation:
 Software validation checks that
the software product satisfies or
fits the intended use (high-level
checking).
 the software meets the user
requirements, not or as needs of
those who will operate the
software only; but, as the needs
of all the stakeholders (such as
users, operators, administrators,
managers, investors, etc.).
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10. Software Validation steps
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11. Internal validation:
 During internal software validation it is assumed that the
goals of the stakeholders were correctly understood and
that they were expressed in the requirement artifacts
precise and comprehensively. If the software meets the
requirement specification, it has been internally validated.
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12. External validation:
 External validation happens when it is performed by
asking the stakeholders if the software meets their needs.
Different software development methodologies call for
different levels of user and stakeholder involvement and
feedback; so, external validation can be a discrete or a
continuous event. Successful final external validation
occurs when all the stakeholders accept the software
product and express that it satisfies their needs
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13. What is basic difference between v&v
( verification and validation )
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14. The terms Verification and Validation are commonly used in
software engineering to mean two different types of
analysis. The usual definitions are:
Verification: Are we building the system right?
Validation: Are we building the right system?
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15.  In other words, validation is concerned with checking that the
system will meet the customer’s actual needs, while
verification is concerned with whether the system is well-
engineered, error-free, and so on. Verification will help to
determine whether the software is of high quality, but it will
not ensure that the system is useful.
 The distinction between the two terms is largely to do with the
role of specifications. Validation is the process of checking
whether the specification captures the customer’s needs,
while verification is the process of checking that the software
meets the specification.
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16. As You Can See In This Diagram
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17. Verification Validation
Verification is a static practice
of verifying documents, design,
code and program.
Validation is a dynamic
mechanism of validating and
testing the actual product.
It does not involve executing
the code.
It always involves executing the
code.
It is human based checking of
documents and files.
It is computer based execution
of program.
It generally comes first-done
before validation.
It generally follows
after verification.
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18. Conclusion:
 1) Verification and Validation both are necessary and
complementary.
 2) Both of them provides its own sets of Error Filters.
3) Each of them has its own way of detect out the errors
left in the software.
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19. Result:
 Lots of people use verification and validation
interchangeably but both have different
meanings. Verification process describes whether the
outputs are according to inputs or not, and validation is
whether the software is accepted by the user or not.
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20. THANK YOU FOR YOUR
ATTENTION!
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