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Software Testing and QualityAssurance (Elective)

Unit 5Session 1

Rajesh Singh01-Oct-2011

Software Testing and Quality Assurance (Elective II 410445) Unit 5

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Topics to be covered in this session:

1)Quality is free

2)Example3)Software Quality4)Quality attributes5)Quality Assurance6)Quality Control7)Cost of Quality8)Summary

Assignment 1- Code Complexity and Case Study of White BoxAssignment 2- Validation Testing and example

1)Smita Joshi (Assignment 1)2)Hardik Gandhi (Assignment 1)3)Tejashree (Assignment 1 and 2)4)Renuka (Assignment 2)5)Soniya Thakur (Assignment 2)6)Shital bajare (Assignment 1)

7)Archana (Assignment 1)


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Quality Is Free

Quality is free? Impossible? Nope, it's true. In 1979, Philip Crosby wrote

in his book Quality is Free: The Art of Making Quality Certain, that indeed

it costs nothing extra (actually it costs less) to produce something of high

quality versus something of low quality.

Given what you've learned so far about software testing and the work

involved in finding and fixing bugs, this may seem impossible, but it's not.

The cost of finding and fixing bugs over time increases. The later bugs are

found, the more they cost not just linearly more, but exponentially more.

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Now, divide the cost of quality into two categories: the costs of

conformance and the costs of nonconformance.

The costs of conformance are all the costs associated with planning and

running tests just one time, to make sure that the software does what it's

intended to do.

If bugs are found and you must spend time isolating, reporting, and

regression testing them to assure that they're fixed, the costs of

nonconformance go up.

These costs, because they are found before the product is released, are

classified as internal failures

If bugs are missed and make it through to the customers, the result will be

costly product support calls, possibly fixing, retesting, and releasing thesoftware, and in a worst-case scenario a product recall or lawsuits. The

costs to address these external failures fall under the costs of

nonconformance

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Example

The last telemetry from Mars Polar Landerwas sent just prior to

atmospheric entry on December 3, 1999. No further signals have been

received from the lander. The cause of this loss of communication is

unknown.

According to the investigation that followed, the most likely cause of the

failure of the mission was a software error that mistakenly identified the

vibration caused by the deployment of the lander's legs as being caused

by the vehicle touching down on the Martian surface, resulting in thevehicle's descent engines being cut off whilst it was still 40 meters above

the surface, rather than on touchdown as planned.
http://en.wikipedia.org/wiki/Image:Mars_polar_lander.jpg

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What is Software Quality

Conformance to explicitly stated functional and performance

requirements, explicitly documented development standards, and implicit

characteristics that are expected of all professionally developed software.

Software Quality aspect of software is measureable so that you can

improve it.

IEEE Definition of "Software Quality

1.The degree to which a system, component, or process meets specified

requirements.

2.The degree to which a system, component, or process meets customer

or user needs or expectations.

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Quality Attributes

Following factors are used to measure software development

quality. Each attribute can be used to measure the product performance.

Reliability

Measure if product is reliable enough to sustain in any condition. Should

give consistently correct results.

Product reliability is measured in terms of working of project under

different working environment and different conditions.

Maintainability

Different versions of the product should be easy to maintain. For

development its should be easy to add code to existing system, should be

easy to upgrade for new features and new technologies time to time.

Maintenance should be cost effective and easy. System be easy to

maintain and correcting defects or making a change in the software.

Usability

This can be measured in terms of ease of use. Application should be user

friendly. Should be easy to learn. Navigation should be simple.

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Portability

This can be measured in terms of Costing issues related to porting,

Technical issues related to porting, Behavioral issues related to porting.

Efficiency

To Major system quality attribute is measured in terms of time required to

complete any task given to the system. For example system should utilize

processor capacity, disk space and memory efficiently. If system is using

all the available resources then user will get degraded performance failing

the system for efficiency. If system is not efficient then it can not be usedin real time applications.

Integrity or security

Integrity comes with security. System integrity or security should be

sufficient to prevent unauthorized access to system functions, preventing

information loss, ensure that the software is protected from virus infection,and protecting the privacy of data entered into the system.

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Testability

System should be easy to test and find defects. If required should be easy

to divide in different modules for testing.

Flexibility

Should be flexible enough to modify. Adaptable to other products with

which it needs interaction. Should be easy to interface with other standard

3rd party components.

ReusabilitySoftware reuse is a good cost efficient and time saving development way.

Different code libraries classes should be generic enough to use easily in

different application modules. Dividing application into different modules

so that modules can be reused across the application.

InteroperabilityInteroperability of one system to another should be easy for product to

exchange data or services with other systems. Different system modules

should work on different operating system platforms, different databases

and protocols conditions.

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Some thing Extra

The so called Quality Movement which was first established in Japan in

1946 by the U.S. Occupation Force's, was based on W. Edwards Deming(USA) research and papers on Statistical Quality Control (SQC).

The QA methods, in manufacturing, proved themselves to work (in

Sales, Customer satisfaction and the right cost of production, i.e. PROFIT)

and were adopted all over the world. QA groups (for manufacturing)

became the norm.

Why cant we apply the same in Software industry and this is how Software

Quality Assurance came into existence.

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Software Quality Assurance

The function of software quality that assures that the standards, processes

and procedures are appropriate for the project and are correctly

implemented.

Software Quality Control

The function of software quality that checks that the project follows its

standards processes, and procedures, and that the project produces the

required internal and external (deliverable) products.

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Example

These terms appear similar but a simple example highlights the fundamental

difference.

Consider a software project that includes requirements, user Interface design and aSQL database implementation.

The SQA team would produce a quality plan that would specify any standards,

processes and procedures that apply to the example project. These might include, by

way of example, IEEE xyzspecification layout (for the requirements), Motif style guide

abc(for the user interface design) and Open SQL standards (for the SQL

implementation). All of the standards, processes and procedures that should be

followed are identified and documented in the quality plan, this is done by SQA.

When the requirements are produced (in this example) the Software Quality Control

team would ensure that the requirements did in fact follow the documented standard

(in this case IEEE xyz). The same task, by SQC, would be undertaken for the user

interface design and the SQL implementation, that is they both followed the standardidentified by SQA. Later the SQA team could make audits to verify that IEEE xyzand

not IEEE abcwas indeed used as the requirements standard.

In this way a difference between correctly implementedby SQA and followedby SQC

can clearly be drawn.

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Cost of Quality

The price of non conformance or the cost of poor quality ,the term 'Cost of

Quality', refers to the costs associated with providing poor quality product or

service.

Research shows that the costs of poor quality can range from 15%-40% of

business costs (e.g., rework, returns or complaints, reduced service levels,

lost revenue).

Most businesses do not know what their quality costs are because they do

not keep reliable statistics. Finding and correcting mistakes consumes an

inordinately large portion resources.

Typically, the cost to eliminate a failure in the customer phase is five timesgreater than it is at the development or manufacturing phase. Effective

quality management decreases production costs because the sooner an

error is found and corrected, the less costly it will be.

S f i d Q li ( l i 0 ) i

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Cost of quality comprises of four elements:

1External Failure Cost - cost associated with defects found after the

customer receives the product or service ex: processing customer

complaints, customer returns, warranty claims, product recalls.

2Internal Failure Cost - cost associated with defects found before the

customer receives the product or service ex: scrap, rework, re-inspection, re-

testing, material review, material downgrades.

3Inspection (appraisal) Cost - cost incurred to determine the degree ofconformance to quality requirements (measuring, evaluating or auditing) ex:

inspection, testing, process or service audits, calibration of measuring and

test equipment.

4Prevention Cost- cost incurred to prevent (keep failure and appraisal cost

to a minimum) poor quality ex: new product review, quality planning, suppliersurveys, process reviews, quality improvement teams, education and

training.

S ft T ti d Q lit A (El ti II 410445 ) U it 5

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Questions:

1)What is software Quality?

2)How can we reduce Cost of Quality?

3)Mention 4 attributes of Software Quality?

4)Difference between SQA and SQC

S ft T ti d Q lit A (El ti II 410445) U it 5

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Thank You for yourPatience!!

If you need some more informationyou can drop me an email at

[email protected]


01-Oct Unit 5 Part 1

Documents

Transcript of 01-Oct Unit 5 Part 1