Model Based Testing – MBT

Model Based Testing: A Game Changer in Software Testing

Picture this: you’re a software tester, responsible for ensuring every nook and cranny of a complex software product functions flawlessly. Quite a task, isn’t it? 

You might be spending countless hours designing test cases and probably realizing that as soon as the software changes, you need to adjust your tests again. Sounds exhausting and time-consuming, right?

That’s where Model Based Testing (MBT) rides in like a superhero! MBT, as the name suggests, is based on models – graphical or mathematical representations of the system. 

Instead of manually writing test cases, you create a model of the system under test, which is used to automatically generate test cases. Think of it as a blueprint that guides you on what to test and how.

The beauty of MBT is that it not only cuts down on manual effort and accelerates the testing process, but it also enhances the quality of the software being tested. The reason? It provides a systematic approach and a comprehensive view of the system’s functionality, ensuring that no aspect is left untested.

Whether it’s a minor tweak in the software or a major system overhaul, all you need to do is adjust the model, and voila, your updated test cases are ready! MBT is indeed transforming the way we test software, making it faster, more efficient, and reliable.

What is Model Based Testing

What is Model Based Testing?

So, you’re probably thinking, “What exactly is Model Based Testing?” Well, imagine you have a blueprint for a building that guides you on how it should be constructed. Similarly, in Model Based Testing (MBT), you have a model, a kind of a roadmap, that describes the system’s functionality. 

Now, instead of manually writing hundreds or even thousands of test cases, you use this model to generate them automatically! It’s a more systematic and streamlined approach to software testing, saving you a whole lot of time and energy.

Types of Model Based Testing

Types of Model Based Testing

Now, let’s talk about the different types of MBT:

State-based Models

These are like our mood swings. Just as we transition from being happy to sad based on certain events, state-based models represent how a system changes its state in response to certain inputs or actions. 

Let’s say you’re testing a music app. The state transitions might involve scenarios like ‘playing’, ‘paused’, or ‘stopped’. By modeling these states and their transitions, you’re better equipped to understand and test how the system behaves in different scenarios.

Data Flow Models

Picture your system as a bustling city and data as its citizens. Data Flow Models help you understand how these citizens (data) navigate through the city (system). They illustrate how data enters the system, the path it follows, where it gets stored, and where it leaves the system. 

So, for an online shopping app, data flow models might show how user information flows from registration through purchase to order confirmation. Understanding this flow allows you to design comprehensive tests that ensure data is handled correctly throughout the system.

Behavioral Models

Imagine you’re a behavior analyst, but your subject is a software system. Behavioral models represent how a system reacts to different events or conditions – in essence, the ‘behavior’ of the system. 

Suppose you’re testing a weather forecasting app. Behavioral models can help you understand and test scenarios like how the system responds when given different geographic coordinates or how it behaves under different weather conditions.

Advantages of Model Based Testing

Of course, MBT is not just for fun! It has some impressive benefits:


Let’s face it, manual test case generation can be monotonous. With MBT, you can automate this process, saving precious time and resources. It’s like delegating the heavy lifting to an incredibly efficient colleague, allowing you to focus on more intricate and creative tasks.


With MBT, your model serves as a comprehensive representation of the system under test, which means the test cases derived from it cover all possible scenarios. It’s like having a detailed map guiding you to explore every corner of a city – you’ll never miss out on an important spot.


Think of MBT as the high-speed train of the testing world. It accelerates test case generation and execution, delivering you to your destination (a thoroughly tested system) faster and more efficiently.


When it comes to software updates or changes, instead of manually adjusting numerous test cases, you have to update the model and generate new test cases from it. It’s as if you have a magic wand that adapts to changes effortlessly.

Disadvantages of Model Based Testing

Now, it’s worth mentioning that every silver lining has a cloud. There are a few challenges to consider with MBT:


Crafting models for MBT can be tricky and requires specialized knowledge. It’s like playing a high-level chess game – you need a solid understanding of the system and a good grip on modeling software testing techniques.

Upfront Costs

MBT can be a bit of an investment to start with, similar to buying a new car. You’ll need the right tools and perhaps some training for your team. 

However, just like a car, it’s a long-term investment that can offer significant returns in terms of time and cost savings down the road.

Model Accuracy

The effectiveness of MBT is only as good as the accuracy of the model. If your model has errors or doesn’t correctly represent the system, it could lead to faulty test cases. 

So, maintaining a meticulous and accurate model is paramount – think of it as ensuring your compass is correctly calibrated when embarking on an adventure.

Despite these challenges, when executed correctly, MBT can be a game-changer, offering numerous benefits and revolutionizing your approach to software testing.

Why MBT (Model Based Testing) is Important?

In the high-velocity world of software development, maintaining a balance between rapid production and the quality of the software becomes a challenging task. This is where Model Based Testing steps in, serving as a critical player in maintaining this balance.

Model Based Testing plays a vital role in automating the labor-intensive and often error-prone process of manually designing and writing test cases. As such, it alleviates the pressure on testers, enabling them to focus more on the strategic and complex aspects of testing.

Furthermore, Model Based Testing provides an opportunity to achieve greater test coverage, ensuring that all possible scenarios are examined and tested, which helps in exposing the hidden bugs and inconsistencies in the software. 

With an increase in coverage, the probability of software failure in the production environment drastically decreases, thereby improving the software quality.

The beauty of Model Based Testing lies in its adaptability and flexibility. In Agile and DevOps environments, where changes are frequent, updating the model to reflect these changes generates new or modified test cases, keeping the test suite always up-to-date. 

Thus, Model Based Testing ensures that the system is validated against the most recent changes, making it highly valuable for maintaining software reliability.

How does Model Based Testing work?

Model Based Testing introduces a new paradigm into the world of software testing. Let’s dive into the steps involved in the Model Based Testing process.

Model Creation

The model is a representation of the software’s functional aspects, often created using specialized modeling languages or tools. 

This process requires an in-depth understanding of the system’s behavior, as it forms the basis for test case generation. The model might include information about various states of the system, transitions, variables, and data flow.

Test Case Generation

Once the model is prepared, it’s time for the magic to happen. The model serves as an input to the algorithms (test case generator) that automatically generate the test cases. These test cases map all possible routes and conditions of the system, ensuring comprehensive test coverage.

Test Case Execution

Generated test cases are then executed against the software system under test, using either manual methods or automated testing tools. It’s here that the software is scrutinized against the expected behavior outlined by the model.

Results Analysis

The final step in the Model Based Testing process is the analysis of the results. The actual behavior of the system is compared with the expected behavior described in the model. Any discrepancies or variations are flagged as defects and passed on to the development team for rectification.

Different Approaches to Create Model Based Test

Creating a model for Model Based Testing is an art that can be approached in several ways. The choice of approach depends on the nature and complexity of the software system under test. Here are some of the popular modeling methods:

Graph-based Models

Graph-based models use nodes to represent states and edges to signify transitions between states. They are visual and intuitive, making them suitable for systems where the flow of control is an essential aspect. Graph-based models help in detecting unreachable states or dead-end paths in the system, thereby improving test coverage.

Finite State Machines

Finite State Machines (FSMs) are mathematical models of computation. In an FSM, the system under test is represented as a machine that can exist in a finite number of states. 

FSMs are especially helpful when the software has observable states and deterministic transitions, such as protocol-based systems.

UML State Chart Diagrams

Unified Modeling Language (UML) state chart diagrams are used when the system under test is complex, involving concurrent activities and nested states. 

These diagrams are rich in semantics, offering constructs like states, transitions, events, and actions, which comprehensively represent the system’s behavior.

How does Model Based Testing improve Test Automation?

Model Based Testing has proven to be a game-changer in the realm of test automation, taking it to a whole new level of efficiency and effectiveness.

Reduction in Manual Effort

Model Based Testing has significantly reduced the manual effort involved in test case design and creation. Testers just need to create an accurate model of the system, and the test cases are generated automatically. 

This has freed up testers to spend more time on strategic tasks like interpreting results and improving the test design.

Acceleration in Test Creation

Another advantage is the acceleration in the test creation process. In conventional testing, creating comprehensive test cases can be a long and tedious process. 

However, with Model Based Testing, you can quickly generate a wide variety of test cases covering all possible paths in the system, greatly speeding up the test creation process.

Enhanced Test Coverage

Test coverage is a crucial factor in testing, and Model Based Testing shines here. The algorithms used for test case generation can systematically cover all paths and states in the model, ensuring a comprehensive set of test cases. 

This high coverage level means that the system is thoroughly tested, minimizing the risk of undetected bugs.

Improved Maintainability

Model Based Testing significantly improves the maintainability of the test suite. When the system changes, you only need to update the model, and new test cases can be generated to cover these changes. 

This adaptability is especially valuable in agile testing and DevOps environments, where changes are frequent, and maintaining the test suite can be challenging.

A Real Case Scenario of Model Based Testing

To put things into perspective, let’s consider a real-life example. Imagine we have a banking application that allows users to perform various operations like checking balance, making transactions, and applying for loans.

In a Model Based Testing approach, a model representing the banking application is created, capturing all the features and possible user interactions. 

For instance, states could be ‘Home Page’, ‘Account Balance Page’, ‘Transaction Page’, and ‘Loan Application Page’. Transitions might include ‘Login’, ‘View Balance’, ‘Make Transaction’, and ‘Apply for Loan’.

Once the model is ready, test cases are generated covering all possible user scenarios. These test cases could include a user logging into their account, checking their account balance, making a deposit, withdrawing money, or applying for a loan.

After the test cases are executed on the application, results are analyzed to ensure that all functionalities of the application work as expected. Any discrepancies are identified as defects and are fixed by the development team.

Drawbacks of Model Based Testing

Model Based Testing is not without its challenges. While it offers significant benefits, there are some drawbacks to consider:

Complexity of Model Creation

Building an accurate model that represents the system’s behavior can be a challenging task, especially for complex systems. It requires a thorough understanding of the system and significant expertise in modeling.

Accuracy of the Model

The effectiveness of Model Based Testing is heavily dependent on the accuracy of the model. Any inaccuracies in the model can lead to misleading test cases and, subsequently, undetected errors in the software.

Initial Cost

The upfront costs for Model Based Testing can be high. This includes the costs of training the testers in model creation and the costs of the tools required for model creation and test case generation.

Example of Model Based Testing

Let’s take a closer look at a simple example of Model Based Testing with a web application’s login feature. The model for this feature might include states like ‘Start’, ‘Username Entered’, ‘Password Entered’, and ‘Logged In’. Transitions would include actions like ‘Enter Username’, ‘Enter Password’, and ‘Click Submit’.

From this model, several test cases could be generated, including:

  • Enter valid username and password -> Click Submit -> Validate ‘Logged In’ state
  • Enter invalid username and valid password -> Click Submit -> Validate error message
  • Enter valid username and invalid password -> Click Submit -> Validate error message

In each of these test cases, the actions represent transitions, and the resulting states are compared with the expected states defined in the model. This approach ensures a systematic and comprehensive validation of the login functionality.

Challenges of Model Based Testing

Challenges of Model Based Testing

While Model Based Testing offers numerous benefits, it’s not without its challenges:

Model Complexity

Creating models for MBT can feel like assembling a thousand-piece jigsaw puzzle. It’s complex and requires a deep understanding of the system and modelling techniques. Getting this right is critical to the success of MBT.

Skilled Personnel

Just like you need an experienced captain to steer a ship safely, you need skilled personnel who understand the nuances of the system and are proficient in modelling techniques to implement MBT effectively. Training your team can require time and resources.

System Changes

Systems evolve over time, and these changes need to be accurately reflected in the model to keep the test cases relevant. This means you’ll need to continuously update your model, which can be a bit like trying to hit a moving target.

Model Accuracy

The phrase “Garbage in, garbage out” applies here. If the model is inaccurate or incomplete, the generated test cases will be flawed. Ensuring the model accurately represents the system is absolutely vital.

Thankfully, there are several tools available to help you navigate the complexities of MBT:


Think of Conformiq as a multitasker in your team. It not only supports automated test design but also takes care of test generation and execution. It’s a comprehensive tool that can cover the whole MBT process, making it easier for you to implement MBT.

Spec Explorer

Straight from the tech giant Microsoft, Spec Explorer is another powerful MBT tool. It generates test cases from models that are defined in either C# or Spec#, giving you a comfortable and familiar environment to define your models.


If you love open-source tools, GraphWalker might be your cup of tea. It uses graphs to create and execute tests. Because it’s open-source, you also get the flexibility to tweak it as per your needs.

Wrapping Up

Model Based Testing, or as we like to call it, the ‘game-changer’ in the world of software testing, has truly revolutionized the way we test software. 

Yes, it comes with its challenges – the model building can be as complex as solving a Rubik’s cube, and ensuring its accuracy is as vital as following the right map on a road trip. But hey, what worthwhile endeavor doesn’t have its hurdles?

When you look at the upside, it’s like striking gold! Automation, efficiency, comprehensive coverage – it’s like the ‘Avengers’ of software testing tools, bringing all these superpowers together. And in the fast-paced world of Agile and DevOps, having such a powerful ally can make a world of difference.

So, if you’re ready to take your software testing process to the next level, then it’s time to embrace Model Based Testing. With the right tools and proper training, it could be your ticket to achieving a more streamlined, thorough, and efficient testing process. 

Frequently Asked Questions

What are the prerequisites for implementing Model Based Testing?

Diving into Model Based Testing is like preparing for a big adventure – you need to be ready! The prerequisites include a deep understanding of the system under test, knowledge of modeling techniques, and the right tools to create the models and generate test cases. And don’t forget, you need a skilled team ready to embark on this exciting journey!

How is Model Based Testing different from traditional testing methods?

If traditional testing methods are like walking, then Model Based Testing is like flying. While traditional methods involve manually writing test cases, MBT automates this process by using a model to generate the test cases. It’s a more systematic, efficient, and thorough approach that ensures comprehensive test coverage.

Can Model Based Testing be applied to any software system?

Model Based Testing is quite the all-rounder. It can be applied to a wide range of software systems. However, it’s particularly useful for complex systems with multiple interacting components. Like a detective with a magnifying glass, MBT helps uncover potential issues across the system’s entire functionality.

Rahnuma Tasnim

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top