Object Oriented Testing In Software Engineering

• Method testing
• Class testing
• Integration testing
• System testing
• Regression testing

Method Testing

Class Testing

• Test each method (and constructor) within a class.
• Test the state behavior (attributes) of the class between methods.
• Class testing is different from conventional testing in that Conventional testing focuses on input-process output, whereas class testing focuses on each method.
• Test cases should be designed so that they are explicitly associated with the class and/or method to be tested. The purpose of the test should be clearly stated.

Each test case should contain:

• A set of commands and actions that will be performed following the test
• A list of potential exceptions while testing the itemA list of external setup requirements (i.e., modifications to the software-external environment required to carry out the test correctly)
• Extra details that will help with comprehending or administering the test Class testing presents the following difficulties because object-oriented software is rich in polymorphism, inheritance, and encapsulation.
• Without creating additional methods that show the status of the class, it is challenging to get a picture of it.
• Retesting is necessary for every new subclass or context of use because a method may be implemented differently (polymorphism). The redefined method may be used by other unchanged methods in the subclass, which require testing.
• While basis path, condition, data flow, and loop tests can be applied to individual methods, they are unable to test how methods interact with one another.

Integration Testing

As object orientation lacks a hierarchical control structure, traditional top-down and bottom-up integration tests are meaningless. Three distinct incremental methodologies can be used with integration testing:

1.  Thread-based testing – which integrates classes required to respond to one input or event.
2.  Use-based testing – which integrates classes required by one use case.
3. Cluster testing – which integrates classes required to demonstrate one collaboration.

Integration testing is performed using the following methods:

• Utilizing the list of class methods, create a number of random test sequences for every client class. Messages will be sent to other server classes by methods.
• Determine which class participates and whose method in the server object corresponds to each generated message.
• Find out which messages are transmitted by each method in the server object (that has been called by messages sent from the client object).
• The next level of methods that are triggered for each message should be identified and included to the test sequence.

System Testing

All rules and methods of traditional systems testing are also applicable to object-oriented systems. Various types of System. Testing include:
Recovery testing: how fast and effectively does the system bounce back from errors

Security testing: Confirm that the system’s built-in security measures will guard against unwanted access (hackers, irate workers, fraudsters).

Stress testing: put the system under unusual strain.

 Performance testing: Examine the performance during runtime in relation to an integrated system.

Regression Testing

Regression testing is done in a manner similar to that of conventional systems to ensure that previously added functionality continues to function. If a tested class is changed, the unit tests automatically need to be redone.
It could be necessary to modify the test scenarios in order to accommodate this test, depending on what has changed. The integration test for that set of classes should also be rebuilt.

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Specialized Techniques For Object Oriented Environment

Fault – Based Testing

Every product must meet the needs of the customer. In order to find problems, testing should start with the analytical model itself. Designing tests with a high likelihood of identifying likely software defects is known as fault-based testing [3]. The analysis and design models should be the first step in fault-based testing. The specification (user manuals, etc.) or the code may serve as the basis for this kind of testing. It functions best when both are used.

Scenario – Based Testing

Instead than focusing on what the product does, this new kind of testing focuses on what the consumer does. This entails documenting the tasks (or use cases, if you will) that the client must complete and then using these tasks and their variations as tests. Naturally, it is better to complete this design work prior to the product’s implementation. It’s actually a result of a meticulous “requirements elicitation” effort. Additionally, interface issues will typically be flushed out in these instances. Compared to fault-based testing, they are more realistic and sophisticated. Because that’s exactly what users do, they frequently test several subsystems at once. At least the higher visibility interaction bugs will be covered by the tests, however they won’t catch everything.

Surface Structure Testing

Object-oriented programming offers an alternative interface design, allowing users to manipulate objects directly instead of completing functions. However, user tasks remain the basis for tests, and understanding and conversing with representative and non-representative users is crucial. Testing requires deceiving ourselves into a different perspective, such as assuming functions are independent of objects and using both functions and objects as hints to identify missed tasks, regardless of the interface type.

Deep (architectural) structure

Surface-based test designs will overlook details. User tasks will be neglected. It will not test important variants that need to be tested. No specific subsystem interactions will be examined. Those oversights could be discovered by examining the deep structure. Various constructs that can be tested using Deep testing are,

• A class diagram shows how things relate to one another. It is possible for an object of one class to contain or use an object of another class.
• More information about the connections between things is provided by the object and interaction diagrams.
• A class diagram illustrating the pattern of inheritance.
• Enhanced state machines, or state charts, are a means to condense a lot of jobs into a little image. Why not, if a state change can be exercised without a test? Once more, the major, user-visible objects are likely to be more useful than the detailed state charts for things hidden deep within the system.

CONCLUSION

Modern software systems depend on object-oriented testing to ensure their functioning and quality. In this article we discussed deeply about the object oriented testing techniques. It is important for the developers and QA teams to understand these testing strategies. Testing teams may guarantee that object-oriented systems continue to be dependable, adaptable, and scalable while simultaneously enhancing maintainability over time by utilizing a variety of testing techniques, including unit testing, integration testing, and polymorphism testing.

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