Chapter SIX Implementation, Testing and

Pragmatics

Making it a reality

Topics

DocumentationCoding, Testing and inspectionOthers

Installation Training Maintenance

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Introduction

Pragmatics concerned with how the system design process we have done so far would be linked to the reality or how it is would give sense or meaning to the stakeholders.

These issues will cover Coding, testing along with documentation and object oriented benefit realization.

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Documentation4

Documentation

There are various types of documentations required in object oriented Software engineering System Documentation: detailed information

about a system’s design specifications, its inner workings, and its functionality.

User Documentation: written or other visual information about an application system, how it works, and how to use it. User documentation is often in the form of online help, sometimes with Web connections for further information.

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Cont…

The system documentation can be for internal or external to the system being developed.  Internal System Documentation: comments in

source code, generated during the coding process or automatically by software compilers or documenters are internal to the system.

External System Documentation: outcomes of all diagrams, including use cases, design classes, activity and sequence diagrams, etc are categorized under this sub category.

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Coding and Testing7

Coding

Translating the design specification in to a working system (a reality)

Two important issues Coding style

To make readable and maintainableAdding as much comments as possible, use

combination of uppercase and lower case in naming …

Programming language selection A language that supports features required

For a web based applications vs window based

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Software Testing

Testing is the process of exercising aA software/program with the specific intent of finding errors prior to delivery to the end user.Testing is Verification and Validation

“Are we building the right system?”“Are we building the system right ?”

What Testing Shows

errorserrors

requirements conformancerequirements conformance

performanceperformance

an indicationan indicationof qualityof quality

Who Tests the Software?

developer independent tester

Understands the system

but, will test "gently"

and, is driven by "delivery"

Must learn about the system,but, will attempt to break it

and, is driven by quality

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Cont…

A failure is an unacceptable behaviour exhibited by a system The frequency of failures measures the reliability An important design objective is to achieve a very low

failure rate and hence high reliability. A failure can result from a violation of an explicit or

implicit requirement

A defect is a flaw in any aspect of the system that contributes, or may potentially contribute, to the occurrence of one or more failures could be in the requirements, the design and the code It might take several defects to cause a particular failure

An error is a slip-up or inappropriate decision by a software developer that leads to the introduction of a defect

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Effective and Efficient Testing

To test effectively, you must use a strategy that uncovers as many defects as possible.

To test efficiently, you must find the largest possible number of defects using the fewest possible tests Testing is like detective work:

The tester must try to understand how programmers and designers think, so as to better find defects.

The tester must not leave anything uncovered, and must be suspicious of everything.

It does not pay to take an excessive amount of time; tester has to be efficient.

Software Testing

Methods

Strategies

white-boxmethods

black-box

methods

White-Box Testing

... our goal is to ensure that all statements and conditions have been executed at least once ...

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Cont…

Also called ‘Glass-box testing’ or ‘structural’ testing

Testers have access to the system design They can

Examine the design documents View the code Observe at run time the steps taken by algorithms and

their internal data Individual programmers often informally employ

glass-box testing to verify their own code

Black-Box Testing

requirementsrequirements

eventseventsinputinput

outputoutput

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Cont…

Testers provide the system with inputs and observe the outputs They can see none of:

The source code The internal data Any of the design documentation describing the system’s

internals

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Writing Formal Test Cases and Test Plans

A test case is an explicit set of instructions designed to detect a particular class of defect in a software system. A test case can give rise to many tests. Each test is a particular running of the test case on a

particular version of the system.

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Test plans

A test plan is a document that contains a complete set of test cases for a system

Along with other information about the testing process. The test plan is one of the standard forms of

documentation. If a project does not have a test plan:

Testing will inevitably be done in an ad-hoc manner. Leading to poor quality software.

The test plan should be written long before the testing starts.

You can start to develop the test plan once you have developed the requirements.

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Information to include in a formal test case

A. Identification and classification: Each test case should have a number, and may also be given a descriptive

title. The system, subsystem or module being tested should also be clearly

indicated. The importance of the test case should be indicated.

B. Instructions: Tell the tester exactly what to do. The tester should not normally have to refer to any documentation in

order to execute the instructions.C. Expected result:

Tells the tester what the system should do in response to the instructions. The tester reports a failure if the expected result is not encountered.

D. Cleanup (when needed): Tells the tester how to make the system go ‘back to normal’ or shut down

after the test.

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The roles of people involved in testing

The first pass of unit and integration testing is called developer testing. Preliminary testing performed by the software

developers who do the design.

Independent testing is performed by a separate group. They do not have a vested interest in seeing as many test

cases pass as possible. They develop specific expertise in how to do good

testing, and how to use testing tools.

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Testing performed by users and clients

Alpha testing Performed by the user or client, but under the

supervision of the software development team. Beta testing

Performed by the user or client in a normal work environment.

Recruited from the potential user population. An open beta release is the release of low-quality

software to the general population. Acceptance testing

Performed by users and customers. However, the customers do it on their own initiative.

Finally

Software testing is four steps procedure Initially, tests focus on each component

individually, ensuring that it functions properly as a unit. makes heavy use of white-box testing

techniques, exercising specific paths in a module's control structure to ensure complete coverage and maximum error detection.

Cont…Next, components must be assembled or

integrated to form the complete software package.

Integration testing addresses the issues associated with the dual problems of verification and program construction. Black-box test case design techniques are the most

prevalent during integration, although a limited amount of white-box testing may be used to ensure coverage of major control paths.

Cont…

After the software has been integrated (constructed), a set of high-order tests are conducted. Validation criteria (established during requirements analysis) must be tested. Validation testing provides final assurance that

software meets all functional, behavioral, and performance requirements. Black-box testing techniques are used exclusively during

validation.

Cont….

The last high-order testing step falls outside the boundary of software engineering and into the broader context of computer system engineering. Software, once validated, must be combined with other system elements (e.g., hardware, people, databases). System testing verifies that all elements mesh

properly and that overall system function/performance is achieved.

Others

Installation Putting the system in to work Direct/phased/parallel/ one site

Training Enabling end users and technical personals to work

and mange the system/software For whom and how much?

Maintenance Providing continuous support as long as the

software/system is alive. Adaptive/perfective/corrective

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Summary

Introduction Understanding motivations and basic concepts

Terminologies , concepts, processes, approaches

Modeling using UML Understanding modeling tools in software

development Types, categories and structure

Requirement elicitation Collecting and organizing users requirement-

WHAT- User needs From function, class, and interface points of view

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Cont…

Requirement Analysis Analyzing and modeling requirements-WHAT

System In terms of Function, Logic and Objects (classes)

System and object design Specifying the new system-HOW

At an architecture level and detail design level

Implementation, testing and Pragmatic Making it a reality

Coding, testing and documentation

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End of The chapter and the course

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