Topic: Test Case Design

Message

   Test Case Design

Testing Methodologies   

Test
case design for software testing is as important as the design of the
software itself. All test cases shall be designed to find the maximum
errors through their execution. 

Testing methodologies are used
for designing test cases. These methodologies provide the developer
with a systematic approach for testing.  

Any software product can be tested in one of the two ways:

1.Knowing
the specific function the product has been designed to perform, tests
can be planned and conducted to demonstrate that each function is fully
operational, and to find and correct the errors in it.

2.Knowing
the internal working of a product, tests can be conducted to ensure
that the internal operation performs according to specification and all
internal components are being adequately exercised and in the process,
errors if any are eliminated. 

The first test approach is called black-box testing and the second is called white-box testing.

The
attributes of both black-box and white-box testing can be combined to
provide an approach that validates the software interface and also
selectively assures that internal structures of software are correct.

The
black-box and white-box testing methods are applicable across all
environments, architectures and applications but unique guidelines and
approaches to testing are warranted in some cases. This document covers
Testing GUIs, and Client/Server Architectures.

The testing methodologies applicable to test case design in different testing phases are as given below:

Black-box Testing
Black-box
tests are used to demonstrate that the software functions are
operational; that input is properly accepted and output is correctly
produced; and that the integrity of external information (e.g., data
files) is maintained. It enables the developer to derive sets of input
conditions (test cases) that will fully exercise all functional
requirements for a program. 

Black-box testing uncovers errors of the following categories:

1.In-correct or  missing functions
2.Interface errors
3.Errors in the data structures or external data base access
4.Performance errors
5.Initialisation and termination errors

Black-box
testing is applied during the later stages of the testing as it
purposely disregards control structure and attention is focused on the
problem domain. Test cases are to be designed to answer the following
questions:

•How is functional validity tested?
•What categories of input will make good test case?
•Is the system particularly sensitive to certain input values?
•How are the boundaries of data input isolated?
•What data rates and data volume can the system tolerate?
•What effect will specific combinations of data have on system operation?

The following black-box testing methods are practically feasible and adopted depending on the applicability:
1.Graph-based testing methods
2.Equivalence partitioning
3.Boundary value analysis

White-box Testing   
White-box
testing of software is designed for close examination of procedural
detail. Providing test cases that exercise specific sets of conditions
and/or loops tests logical paths through the software.

Unfortunately,
even for few LOC, the numbers of paths become too many and present
certain logistic problems. Due to this, a limited number of important
logical paths can be selected and exercised. Important data structures
can be probed for validity. 

White box testing is a test case
design method that uses the control structure of the procedural design
to derive test cases. The test cases derived from white-box testing
methods will:

1.Guarantee that all independent paths within a module have been exercised at least ones
2.Exercise all logical decisions on their true and false sides
3.Execute all loops at their boundaries and within their operational bounds
4.Exercise internal data structures to ensure their validity.

White
box testing need to be adopted under Unit level testing strategy. It
can be adapted to a limited extent under integration testing if
situation warrants for it. Basis path testing and control structure
testing are some of the most widely used white-box testing techniques.

Author	Message
tanushree Senior Member Joined: 04Apr2007 Online Status: Offline Posts: 2160	Topic: Test Case Design Posted: 17Oct2007 at 3:40am
	Test Case Design Testing Methodologies Test case design for software testing is as important as the design of the software itself. All test cases shall be designed to find the maximum errors through their execution. Testing methodologies are used for designing test cases. These methodologies provide the developer with a systematic approach for testing. Any software product can be tested in one of the two ways: 1.Knowing the specific function the product has been designed to perform, tests can be planned and conducted to demonstrate that each function is fully operational, and to find and correct the errors in it. 2.Knowing the internal working of a product, tests can be conducted to ensure that the internal operation performs according to specification and all internal components are being adequately exercised and in the process, errors if any are eliminated. The first test approach is called black-box testing and the second is called white-box testing. The attributes of both black-box and white-box testing can be combined to provide an approach that validates the software interface and also selectively assures that internal structures of software are correct. The black-box and white-box testing methods are applicable across all environments, architectures and applications but unique guidelines and approaches to testing are warranted in some cases. This document covers Testing GUIs, and Client/Server Architectures. The testing methodologies applicable to test case design in different testing phases are as given below: Black-box Testing Black-box tests are used to demonstrate that the software functions are operational; that input is properly accepted and output is correctly produced; and that the integrity of external information (e.g., data files) is maintained. It enables the developer to derive sets of input conditions (test cases) that will fully exercise all functional requirements for a program. Black-box testing uncovers errors of the following categories: 1.In-correct or missing functions 2.Interface errors 3.Errors in the data structures or external data base access 4.Performance errors 5.Initialisation and termination errors Black-box testing is applied during the later stages of the testing as it purposely disregards control structure and attention is focused on the problem domain. Test cases are to be designed to answer the following questions: •How is functional validity tested? •What categories of input will make good test case? •Is the system particularly sensitive to certain input values? •How are the boundaries of data input isolated? •What data rates and data volume can the system tolerate? •What effect will specific combinations of data have on system operation? The following black-box testing methods are practically feasible and adopted depending on the applicability: 1.Graph-based testing methods 2.Equivalence partitioning 3.Boundary value analysis White-box Testing White-box testing of software is designed for close examination of procedural detail. Providing test cases that exercise specific sets of conditions and/or loops tests logical paths through the software. Unfortunately, even for few LOC, the numbers of paths become too many and present certain logistic problems. Due to this, a limited number of important logical paths can be selected and exercised. Important data structures can be probed for validity. White box testing is a test case design method that uses the control structure of the procedural design to derive test cases. The test cases derived from white-box testing methods will: 1.Guarantee that all independent paths within a module have been exercised at least ones 2.Exercise all logical decisions on their true and false sides 3.Execute all loops at their boundaries and within their operational bounds 4.Exercise internal data structures to ensure their validity. White box testing need to be adopted under Unit level testing strategy. It can be adapted to a limited extent under integration testing if situation warrants for it. Basis path testing and control structure testing are some of the most widely used white-box testing techniques. Post Resume: Click here to Upload your Resume & Apply for Jobs

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suresh5003 Newbie Joined: 18May2009 Online Status: Offline Posts: 1	Posted: 19May2009 at 12:00am
	< ="Content-" content="text/; charset=utf-8">< name="ProgId" content="Word.">< name="Generator" content="Microsoft Word 12">< name="Originator" content="Microsoft Word 12"><> In software Testing Test Design is the important for software testing itself, to reduce the testcases as minimum as possible and find more defects There is a tool called TestersDesk.com which is used specially for Test Design and Test Data Generation Tools, There are different types of tools which are used to reduce the testcases into little number, I can explain clearly with good example PairWise TestCase Generator This tool will be useful in the situations where several parameters exist each of which take several values resulting a high number of Test combinations, to reduce that combinations into a little number we are using this tool. It will cover almost 80-90% of Test coverage. It will cover single fault determination. For Example: Net connections: Tata, Reliance, Airtel Browsers: IE6, IE7, IE8 Platforms: XP, XP2, XP3, Vista Ram: 1GB, 2GB, 3GB Manually if we generate the combinations it will generate 108 pair combinations like 1) Tata-IE6-XP-1GB 2) Reliance-IE7-XP2-2GB etc but our pairwise TestCase Generator Generates into a little number 13 which is very simple for the Tester to test those 13 pair combinations. PairWise Testing can be used mainly when we have to find critical defects.
	Suresh
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