UNIT – IV TESTING CS2301, SOFTWARE ENGINEERING,

1. Define software testing?

            Software testing is a critical element of software quality assurance and represents the ultimate review of specification, design, and coding.

2. What are the objectives of testing?

i. Testing is a process of executing a program with the intend of finding an error.

ii. A good test case is one that has high probability of finding an undiscovered error.

iii. A successful test is one that uncovers as an-yet undiscovered error.

3. What are the testing principles the software engineer must apply while performing the software testing?

i. All tests should be traceable to customer requirements.

ii. Tests should be planned long before testing begins.

iii. The pareto principle can be applied to software testing-80% of all errors uncovered during testing will likely be traceable to 20% of all program modules.

iv. Testing should begin “in the small” and progress toward testing “in the large”. v. Exhaustive testing is not possible.

vi. To be most effective, an independent third party should conduct testing.

4. What are the two levels of testing?

i. Component testing - Individual components are tested. Tests are derived from developer’s experience.

ii. System Testing - The group of components are integrated to create a system or sub-system is done. These tests are based on the system specification.

5. What are the various testing activities?

i. Test planning

ii. Test case design

iii. Test execution

iv. Data collection

v. Effective evaluation

6. Write short note on black box testing.

The black box testing is also called as behavioral testing. This  method  fully focus on the functional requirements of the software. Tests are derived that fully exercise all functional requirements.                                                                                                         

7. What is equivalence partitioning?

Equivalence partitioning is a black box technique that divides the input domain into classes of data. From this data test cases can be derived. Equivalence class represents a set of valid or invalid states for input conditions. 

 

8. What is a boundary value analysis?

A boundary value analysis is a testing technique in which the elements at the edge of the domain are selected and tested. It is a test case design technique that complements equivalence partitioning technique.

9. What are the reasons behind to perform white box testing?

There are three main reasons behind performing the white box testing.

1. Programmers may have some incorrect assumptions while designing or implementing some functions.

 2. Certain assumptions on flow of control and data may lead programmer to make design errors. To uncover the errors on logical path, white box testing is must.

3. There may be certain typographical errors that remain undetected even after syntax and type checking mechanisms. Such errors can be uncovered during white box testing.

10. What is cyclomatic complexity?

Cyclomatic complexity is software metric that gives the quantitative   Measure of logical complexity of the program.                                                                                                                                                                                                      

11. How to compute the cyclomatic complexity?

The cyclomatic complexity can be computed by any one of the following ways. 

   1. The numbers of regions of the flow graph correspond to the cyclomatic complexity.

              2. Cyclomatic complexity (G), for the flow graph G, is defined as: V(G)=E-N+2, E -- number of flow graph edges, N -- number of flow graph nodes

            3. V(G) = P+1 Where P is the number of predicate nodes contained in the flow graph.

12. Distinguish between verification and validation.

Verification refers to the set of activities that ensure that software correctly implements a specific function.Validation refers to a different set of activities that ensure that the software that has been built is traceable to the customer requirements.

13. What are the various testing strategies for conventional software?

i. Unit testing

ii. Integration testing.

iii. Validation testing.

iv. System testing.

14. Write about drivers and stubs.

Drivers and stub software need to be developed to test incompatible software.The “driver” is a program that accepts the test data and prints the relevant results.The “stub” is a subprogram that uses the module interfaces and performs the minimal data manipulation if required.

15. What are the approaches of integration testing?

The integration testing can be carried out using two approaches.

1. The non-incremental testing.

2. Incremental testing.

16. What are the advantages and disadvantages of big-bang?

Advantage:

This approach is simple.

Disadvantages:

It is hard to debug.

It is not easy to isolate errors while testing.

In this approach it is not easy to validate test results.

                       

17. What are the benefits of smoke testing?

* Integration risk is minimized.

* The quality of the end-product is improved.

* Error diagnosis and correction are simplified.

* Assessment of program is easy.

18. What are the conditions exists after performing validation testing?

* The function or performance characteristics are according to the specifications and are accepted.

* The requirement specifications are derived and the deficiency list is created.

19. Distinguish between alpha and beta testing

Alpha and beta testing are the types of acceptance testing.

            Alpha test : The alpha testing is attesting in which the version of complete software is tested by the customer under the supervision of developer. This testing is performed at developer’s site.

            Beta test : The beta testing is a testing in which the version of the software is tested by the customer without the developer being present. This testing is performed at customer’s site.

20. What are the various types of system testing?

1. Recovery testing – is intended to check the system’s ability to recover from failures. 

2. Security testing – verifies that system protection mechanism prevent improper penetration or data alteration.                        

3. Stress testing – Determines break point of a system to  establish   maximum service level.  

4.Performance testing – evaluates the run time performance of the software, especially real-time software.

21. Define debugging.

Debugging is defined as the process of removal of defect. It occurs as a consequence of successful testing.

22. What are the common approaches in debugging?

Brute force method:

 The memory dumps and run-time tracks are examined and program with write statements is loaded to obtain clues to error causes.

Back tracking method:

The source code is examined by looking backwards from symptom to potential causes of errors.

Cause elimination method:

This method uses binary partitioning to reduce the number of locations where errors can exists

23. What is meant by structural testing?

            In structural testing derivation of test cases is according to program structure. Hence knowledge of the program is used to identify additional test cases.

24. What is meant by regression testing?

                                    Regression testing is used to check for defects propagated to other modules by changes made to existing program. Thus, regression testing is used to reduce the side effects of the changes.      25. What is meant by unit testing?

                                    The unit testing focuses verification effort on the smallest unit of software design, the software component or module.