State Transition Testing In Software Testing

State Transition Testing is one of the black box testing techniques. in our previous post, we discussed other detailed testing techniques, like Boundary Value Analysis, Equivalence Partitioning, and Decision Table Techniques.

In this post, we will clear all the doubts that come to our minds while implementing State Transition Testing. So, Let’s start with a small introduction to State Transition Testing.

What is state transition testing?

A state transition test is any test where you write a sequence of input values and check if that sequence causes the system to transition from its initial state into some other state and then check what happens after that.

If the post state is correct, the initial state is valid. This approach can also be applied to more than two states by transitioning the system into multiple states.

State transition testing predicts how a system will respond when given different inputs. This helps to analyze the application’s behavior for any input conditions, whether expected or not. to do this, the Tests can provide positive and negative input values and record the software’s behavior.

When to Use State Transition?

The basic purpose of a state transition test is to define the success and failure criteria by identifying appropriate transitions between states. This can be achieved through detailed State Transition testing techniques discussed below.

Based on your project requirements, you need to decide when to use state transition during feature testing:

When there are alternative paths for the user to complete a task, each path should have an associated state transition test.

Why State Transition?

Using state transition, you can test the software in different scenarios and conditions that might take place for your application during execution so that it works fine as expected. apart from this, State Transition testing has many advantages:-

It gives us an idea of what happens when we enter invalid data into the fields.

Setting up the correct validation for a field is easier when you know which states correspond to valid values.  When your application saves data to a file or database, it will fail with an error if the fields have invalid characters. This happens far more often than we think, so it’s important that you test these cases and handle them correctly. State transition reveals problems early in the development cycle, saving time and money. Writing a test script for state transition tests is relatively easier than writing test cases of normal functionality testing.

Testing Architecture is not affected by State Transition Testing as this type of testing approach can be implemented into any application architecture level without changing it. This is one of the key reasons for implementing State Transition Testing.

State Transition Diagram and State Transition Table

The State Transition Table and State Transition Diagram are closely related. State transition diagrams show a high-level view of the entire state transitions in an application.

It depicts all possible conditions for system input and shows various user activities with respect to these inputs, leading to different states of the application. The State Transition table provides more detailed information about actual values that can be used in the test cases and the expected output for that input condition.

State Transition Table

State Transition Table is a Test Data Builder tool that gives complete information about each row and the inputs for different rows/columns and their expected values.

State Transition Diagram

i.e., For State Transition Diagram: There could be a scenario where a user/ tester needs to enter the value of “A” in a field. If that causes the system to transition from its initial state into some other state, then check what happens after that.

State Transition Testing is also called a State-based testing approach.

The name is because the test shows the software would behave in different states based on the input provided by a tester or user.

This type of testing is very similar to the unit testing approach where if you test a class at one time, that unit would not be tested again and again for each test case under Integration Testing.

In the state transition, there might be one scenario where the input has failed the system, which would not go into that state again as we are dealing with flows in the state transition, and a failure might have occurred at any one time.

State Transition Testing

State transition testing considers transactions that change data through multiple states and tests how the program behaves in each possible state (as shown below).

This approach is available for various applications like Web Applications, Desktop or Mobile Applications, etc. This approach will help testers to map out all these different possible scenarios.

Here, we will explain with an example of a web application that uses different types of pages and includes checkboxes, radio buttons, etc.

For example, clicking the “Send” button from the Welcome page will go into the Contact Page, where there are 2 radio buttons: Email Address or Phone No. If the user selects “Email Address,” it will go to Contact Page; otherwise, it will go into Help Pages.

Disadvantages of State Transition Testing:

This type of testing needs a lot of effort to create test data. A tester must create test data for every situation an application might reach. For this purpose, the tester has to create a set of input values like ” A “, ” B “, ” A & B “, “AB,” etc., to be provided for state transition.

Needs a very good understanding of the application under test. Requires major effort in advance to create all possible test data, which can lead to time delays. It needs good effort at a later stage when the requirement is that of adding features to an existing application.

Advantages of State Transition Testing

The state transition approach is one of the most widely used in software testing. This could be because it is easy to understand by people, testers, and developers alike, as it depicts the sequence or flow of events for a particular state/state transition. One main advantage is that it ensures that no case is left untested.

State Transition Testing can be performed even on legacy applications. If you have any setup where an application will go into a particular state only when certain values are entered at input fields, then State Transition Testing can be adopted as one of the testing techniques to test and verify the same.

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