1. Model Based Testing Venkata Ramana Bandari, Expert Software Engineer
Thrivikram Reddy, Expert Software Engineer
Allscripts India LLP

2. Abstract
The complexity of software applications continues to increase, and the user’s aversion to software defects is greater than ever, so the functional testing should become more efficient at discovering bugs. The cost and time of testing is a significant dimension of any projects and sometimes topping the costs of development.

3. Model of Software
A Model of Software is a representation of its behavior. Behavior can be described in terms of the
Input sequences accepted by the system
The actions performed by the system as designed
Conditions applied on the actions performed by the system as designed
Output logic or the flow of data through the application’s modules and procedures
By using modeling, a shareable, reusable, detailed description of the system is acquired.

4. What is Model Based Testing
“Model-based testing is a process for derivation of test cases from a model that describe functional aspects of the system under test (SUT) and executing those test cases.”
This approach renews the whole process of functional software testing from business requirements to the test repository with test execution.
It supports the phases of designing and generating tests, documenting the test repository, producing and maintaining the bi-directional traceability matrix between tests and requirements.
Test Requirements
Exit
Test Derivation
Test Execution
Executable test Suite Compilation
Abstract Test Suite
Executable test Suite
Reports
Model

5. Fundamental tasks of MBT
Understanding The System: Forming a intellectual representation of the system’s functionality is a prerequisite to building models.
Determine the components/features that need to be tested based on test objectives.
Establish communication with requirements, design, and development teams if possible.
Identify the users of the system.
Enumerate the inputs and outputs of the Application.
Study the sequences of inputs and Outputs that need to be modeled.
Understand internal data interactions and computation.
Choosing the Model: There are no software models today that fit all intents and purposes. Consequently, for each situation decisions need to be made as to what model (or collection of models) are most suitable.

6. Fundamental tasks of MBT(cont’d)
Building the Model:
The general procedure that underlies many MBT methodologies:
Make a list of the inputs and Outputs.
Input applicability constraints for each input.
For example, consider a simple telephone. The input “take the handset off the hook” can only be applied when the handset is hung up. (It is impossible to pick up the handset if the handset has already been picked up.)
Input behavior constraints for each input according to the current state context.
For example, the input “take the handset of the hook” can cause a number of behaviors.
If the context is that the phone is idle, the resulting behavior will be that the system will generate a dial tone.
If the context is that the phone is ringing due to an incoming call, then the system will connect the two phones to allow conversation.
Two different behaviors are caused by the same input.

7. Example: How to Design model for Calculator
Select Standard
Not Running Standard
Start
Stop
Running Standard
Running Scientific
Not Running Scientific
Select Scientific
Not Running
Running
Start
Stop

8. What Does This Model Care About?
Application status
Standard
Scientific?
Mode status
Running
Not Running
Display status
Empty
Not Empty
In Natural Language
If the Calculator is Not Running then the user can execute ‘Start’.
When the user executes ‘Start’, the Calculator goes to ‘Running’ mode
If the Calculator is Running then the user can execute ‘Standard’.
When the user executes ‘Standard’, the Calculator goes to ‘Standard’ mode and the display is cleared.
When the User Executes ‘Scientific’, the calculator goes to ‘Scientific’ mode and the display is cleared
When the user enter number the display will show with number
When the user click on off button, calculator will move to not running mode.

9. Benefits of Model-Based Testing
It helps to detailed understanding of the system behavior
Easy test case maintenance, Test suite grows with the product
Reduced costs/Time/more tests, Manage the model instead of the cases
Systematic coverage, Helps early bug detection
When a new feature is added, a new action is added to the state machine to run in combination with existing actions.
Improved tester job satisfaction

10. Drawbacks of MBT
Excessive amount of skills is required from the testers. They need to be familiar with the model, which means knowledge of different forms of application.
Large initial effort in terms of man-hours is required to get into modeling and selecting the level for modeling.

11. Conclusion
Models are an excellent way to represent and understand system behavior.
Testers construct intellectual models anyway during their testing. Those mental models can be transformed to models on paper. This helps testers to achieve readability and re-usability
Models provide an easy way to create and update tests.

12. Venkata Ramana Bandari
Author’s Biography
Venkata Ramana Bandari
Working as Expert Software Engineer in software industry having 12+ years of experience in software testing. Extensive experience in Database testing, Product testing, Regression testing, Functional testing, UAT testing, integration testing, Patch Management. Good knowledge of Testing Methodologies (V- Model, Agile) Well Versed in conducting different kind of tests such as User acceptance Testing (UAT), Regression, Integration, Smoke, Sanity and Cloud based applications testing.
Thrivikram Reddy
Working as Expert Software Engineer in software Industry having 11+ years of experience in software testing. Experienced Quality Engineer in automation with a demonstrated history of working in the healthcare software industry. Skilled in Test Automation, Selenium WebDriver and C#. Also, exploring usage of python to automate things. Passionate about learning the new technologies and implementation.

13. Thank You!!!