What are merits and demerits of sequential test approach?

Each and every development process in this world follows a sequential approach for its development. Similarly software development is carried out with a sequential approach.
A software development plan is called system development methodology or software development methodology.

- It can be defined as a frame work that is used to plan, structure and control the whole process of development of information software or system.

- The sequential approach is followed in every aspect of software engineering whether it be development or testing to keep the development systematic and on track.

Sequential approach to testing has got both merits and demerits.
As sequential approach to testing is followed in which testing is seen as flowing steadily downwards through the phases or levels of different and various kinds of testing like performance testing, unit testing, integration testing, alpha testing, beta testing etc. the sequential approach to testing is based on certain principles which have been stated below:

- Testing plan is divided in to sequential phases. Some splash back and over lapping is accepted between any two phases of testing to a certain extent.

- More emphasis is on testing, deadlines or target dates, time schedules, implementation and budget of an entire software or system at one time.

- A very control is kept over the testing of a software system or application via extensive formal reviews and documentation, approval by the client or the customer and users.

- Control is also maintained over information technology management which is done mostly at the end of most of the phases before the beginning of a phase of testing.

Though, Sequential approach is a traditional approach to development in software engineering, it has been badly blamed for several large scale software projects over time, over budget and some times for failures in timed delivery.

- This basically happens due to big design up front approach.

- At other times this approach has been superseded by more versatile and flexible methodologies developed especially for development of software system or applications.

- This sequential testing approach is frequently used in software processes of software development.

The whole software development progress is seen flowing steadily downwards through the following phases:
- Phase of requirements specifications
- Phase of conception
- Phase of initiation
- Phase of analysis
- Phase of designing
- Phase of construction
- Phase of coding
- Phase of integration
- Phase of testing
- Phase of debugging
- Phase of validation
- Phase of production
- Phase of implementation
- Phase of installation and
- Phase of maintenance

This sequential approach basically originated in construction and manufacturing industries. This hardware oriented model or sequential approach to development was simply adopted for the development of software systems or applications also.

- While following a sequential approach it should be made sure that before moving on to the next phase, the preceding phase is perfectly completed.

- However some cases may include some slight variations.

- It’s been a observed fact that time spent in early phases of the software development process has great benefits.

- A bug or an error found in early levels of testing cost less as compared to those found in later stages of development.

- It also requires less efforts and time to repair or fix.

- If a program design or structure after development turns out to be impossible to implement than it will be a complete waste of efforts and time.

- It is easier to fix the errors and bugs in the early stages than to realize later that all the work done is of no use.

Thus following a sequential approach makes sure each and every step is 100 percent perfect and the testing process can be carried on further.

What are merits and demerits of ad hoc test approach?

Ad hoc testing as the name suggests is the testing that is carried out without any formal planning and formal documentation though it can be used for scientific experimental studies.

- The ad hoc testing is meant to be carried out only once until and unless a defect is found.
- It would not be wrong if we call the least formal methodology of testing a software application or system.
- It has always been under criticism because of its uneven structure and also because the defects discovered through this kind of testing are difficult to reproduce due to a lack of written test cases.

However, there is still a plus point of ad hoc testing as important defects or bugs can be found quickly and easily without much efforts and pre planning.

Principle of Ad-hoc testing
The ad hoc testing is based on the principle of improvisation i.e., the software testers seek to find the errors and bugs by any means that seems appropriate to him/ her or we can say tests are performed according to the convenience of the tester.

Ad hoc testing can be appropriately called a primitive version of error guessing which itself is an un- sophisticated version of exploratory testing.

- Formal testing is carried out without any test cases and it proves to be a great help in deciding the duration and scopes for the other types of testing that have to be carried out upon the software system or application.

- This also helps the tester to learn more and more about the software system or application prior carrying out the other kinds of testing.

- It can be called as the least formal method of testing.

- The quick discovery of defects is the best use of ad hoc testing.

- Only reading the specifications and requirements doesn’t give a good sense of how the program or the software system or the application actually works and behaves.

- Even the documentation of the testings does not provide the feel of the software system or application.

- Ad hoc testing can be effectively used to find discrepancies in the testing strategies of the tester and the relations between the sub- systems of the software can be explored that would have been left un- exposed.

- In a way we can say that it serves a tool for checking the quality of our testing methodology.

- It helps in finding the missing cases and so these can be added to the list of test cases.

- Discovering new test cases with ad hoc testing is an indication that root cause analysis should also be performed.

While carrying out the ad hoc testing you should ask yourself and your team members “what other tests should we need to carry out in order to supplement this and make testing more effective?”

SOME IMPORTANT FACTS
- Defects or errors found during ad hoc testing provide examples of forgotten test cases.

- Determining the priority for carrying out other testing can also be thought as another use of ad hoc testing.

- For example, if a program allows the user to carry out some task and the ad hoc testing shows that this function works well, then the formal testing of this functionality might be postponed until the areas having problems are completed.

- On the other hand, if the ad hoc testing discovers any problem, then the formal testing for this functionality can be given highest priority.

- It is concerned with application testing without taking into considerations any rules and regulations.

- For carrying out ad hoc testing effectively the tester should have strong knowledge of the software system or application. Ad hoc testing is performed mainly to save time.