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- At other times this approach has been superseded by more versatile and flexible methodologies developed especially for development of software system or applications.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