- Software Testing is designed to establish that the software is working satisfactorily as per the requirements.
- Software Testing is a process designed to prove that the program is error free.
- Software The job of testing is to certify that the software does its job correctly and can be used in production.

Because, with these as the guidelines, one would tend to operate the system in a normal manner to see if it works and one would unconsciously choose such normal/correct test data as would prevent the system from failing. Besides, it is any way not possible to certify that a software has no errors, simply because it is almost impossible to detect all errors.

In a way, we can say that software testing is basically a task of locating errors.

From the objective point of view, testing can be done in two ways:

Positive Testing: Operate application or software as it should be operated. Use proper  variety of test data, including data values at boundries to test if it fails. Check actual test results with the expected and see

- Does it behave normally?
- Are results correct?
- Does the software function correctly?

Negative Testing: Test for abnormal operations.  Test with illegal / abnormal test data. Intentionally attempt to make things go wrong and to discover / detect and see

- Does the system fail / crash?
- Does the program do what it should not?
- Does it fail to do what it should?

Positive view of Negative Testing: The job of testing is to discover errors before the user does. A good tester is one who is successfull in making the system fail. Mentality of the tester has to be destructive – opposite to that of the creator / developer which should be constructive.

Model-based testing involves developing and using a data mode to generate tests. The model is essentially a specification of the inputs to the software. The suite includes inputs, expected outputs and necessary infrastructure to run the tests automatically. Testers using MBT approach concentrate on a data model and genration infrastructure instead of hand crafting individual tests.

It is essentially meant for functional testing and is a black box testing technique.

MBT is based on the premise that the reliability of the test process that can ensure the high quality of software demands that the test cases be derived form functional specifications. The test cases should guarantee that the functionality called out in specifications is completely covered and that the application can be fully excercised through execution of test cases. If testers can indeed develop such test cases directly from functional specifications, the at least functional specifications can not be faulted for corresponding deficiency in the application and it can be reasonably hoped that the desired functionality may have been sucessfully translated into the delivered application. MBT models tests based on the specifications.

MBT separates the testing logic from the actual test implemantation. This allows the developer to focus on developing good tests specific to the application while relying on the automation tool’s test execution environment to solve problems related to test execution.

MBT has as its roots applications in hardware testing, most notably telephone switched and recently has spread to a wide variety of software domains.

MBT is directly applicable for supporting mission critical applications, in fact MBT becomes imperative. NASA and the Europe space agency have already implemented model based testing.

There is promising future for MBT as software becomes even more ubiquitous and quality becomes the only distinguishing factor between brands. Modelling in general seems to be gaining favour particularly in domains where quality is essential and less than adequate software is not an option.

MBT is a natural choice for testers concerned about completeness, effectiveness and efficiency.