--- description: State Transition testing is defined as the testing technique in which changes in input conditions cause's state changes in the Application under Test (AUT). title: State Transition Testing with Example image: https://www.guru99.com/images/state-transition-testing-1.png --- [Skip to content](#main) **⚡ Smart Summary** State Transition Testing is a black-box technique that validates how an application moves between states as input conditions change. This tutorial explains the four diagram parts, the difference between state diagrams and tables, and worked ATM and login examples for testers. * 🔄 **Core Idea:** The technique checks system behavior when the same input produces different outputs based on prior events (a finite-state system). * 🧩 **Four Building Blocks:** Every model is built from States, Transitions, Events, and Actions. * 🗺️ **Diagram vs Table:** Diagrams reveal valid transitions; tables expose invalid transitions. * 🏧 **Practical Examples:** ATM PIN lockout and flight-reservation login demonstrate real coverage. * 🤖 **AI Enablement:** AI tools auto-generate state models from requirements and flag missing or invalid transitions. [ Read More ](javascript:void%280%29;) ![State Transition Testing — States]() ## What is State Transition Testing? **State Transition Testing** is a black-box testing technique in which changes in input conditions cause state changes or output changes in the Application Under Test (AUT). It helps analyze the behavior of an application for different input conditions, and testers can provide positive and negative input values while recording the system’s behavior. It is based on the model on which the system and the tests are built. Any system where you get a different output for the same input — depending on what happened before — is a finite-state system. The State Transition Testing technique is helpful where you need to **test different system transitions**. ## When to Use State Transition Testing * When a tester is testing the application for a finite set of input values. * When the tester is testing a sequence of events that occur in the AUT, allowing the application’s behavior to be checked for a sequence of input values. * When the system under test depends on events or values from the past. ## When Not to Rely on State Transition Testing * When the testing is not done for sequential input combinations. * When the testing targets different functionalities, such as exploratory testing. ## Four Parts of a State Transition Diagram There are four main components of the State Transition model, described below. **1) States** that the software might reach. [](https://www.guru99.com/images/1/103017%5F0527%5FWhatIsState1.png) **2) Transition** from one state to another. [](https://www.guru99.com/images/1/103017%5F0527%5FWhatIsState2.png) **3) Events** that trigger a transition, such as closing a file or withdrawing money. [](https://www.guru99.com/images/1/103017%5F0527%5FWhatIsState3.png) **4) Actions** that result from a transition, such as an error message or being given cash. [](https://www.guru99.com/images/1/103017%5F0527%5FWhatIsState4.png) ## State Transition Diagram vs State Transition Table There are two main ways to represent or design state transition: the state transition diagram and the state transition table. | Aspect | State Transition Diagram | State Transition Table | | -------------------- | ---------------------------------------- | ------------------------------------------ | | Also called | State Chart / Graph | State Table | | Representation | Boxes for states, arrows for transitions | Grid of states (rows) and events (columns) | | Best for identifying | Valid transitions | Invalid transitions | | Each cell shows | — | The state reached after an event occurs | ## How to Make a State Transition (Examples) ### Example 1: ATM PIN Lockout Consider an ATM system function where, if the user enters the invalid password three times, the account is locked. In this system, if the user enters a valid password in any of the first three attempts, the user is logged in successfully. If the user enters the invalid password on the first or second try, they are asked to re-enter it. Finally, if the user enters the incorrect password a third time, the account is blocked. ### State Transition Diagram (Example 1) [](https://www.guru99.com/images/2/state%5Ftransition.png) In the diagram, whenever the user enters the correct PIN, they move to the Access Granted state. If they enter the wrong password, they move to the next try, and if they do the same a third time, the Account Blocked state is reached. ### RELATED ARTICLES * [What is Requirements Traceability Matrix (RTM) in Testing? ](https://www.guru99.com/traceability-matrix.html "What is Requirements Traceability Matrix (RTM) in Testing?") * [Agile Test Automation Framework ](https://www.guru99.com/automation-testing-agile-scrum.html "Agile Test Automation Framework") * [Types of Unit Testing ](https://www.guru99.com/types-of-unit-testing.html "Types of Unit Testing") * [Top 6 Generative AI Testing Tools (2026) ](https://www.guru99.com/generative-ai-testing-tools.html "Top 6 Generative AI Testing Tools (2026)") ### State Transition Table (Example 1) | State | Correct PIN | Incorrect PIN | | ----------------------- | ----------- | ------------- | | **S1) Start** | S5 | S2 | | **S2) 1st attempt** | S5 | S3 | | **S3) 2nd attempt** | S5 | S4 | | **S4) 3rd attempt** | S5 | S6 | | **S5) Access Granted** | – | – | | **S6) Account Blocked** | – | – | In the table, when the user enters the correct PIN, the state transitions to S5 (Access Granted). If the user enters a wrong password, they move to the next state, and after the third wrong attempt they reach the Account Blocked state. ### Example 2: Flight Reservation Login In the flight reservation login screen, you must enter the correct agent name and password to access the [flight reservation application](https://www.guru99.com/uft-qtp-flight-reservation.html). [](https://www.guru99.com/images/1/103017%5F0527%5FWhatIsState5.png) _State Transition Graph_ The application allows three attempts; if the user enters the wrong password on the fourth attempt, the system closes the application automatically. The State Graph helps you determine valid transitions to be tested. Testing with both the correct and an incorrect password is compulsory, and for the [test scenarios](https://www.guru99.com/test-scenario.html), logging in on the 2nd, 3rd, or 4th attempt could each be tested. You can use a State Table to determine invalid system transitions. [](https://www.guru99.com/images/2/state%5Ftransition%5Ftest.png) In a State Table, all valid states are listed on the left and the events that cause them across the top. Each cell shows the state the system moves to when the event occurs. For example, in state S1, a correct password takes you to S6 (Access Granted); a wrong password on the first attempt takes you to S3 (2nd Try). Likewise, you can determine all other states. Two invalid states are highlighted using this method. Suppose you are in state S6 (already logged in) and you open another instance of flight reservation and enter passwords for the same agent. The system response for such a scenario needs to be tested. ## Advantages and Disadvantages of State Transition Technique | Advantages | Disadvantages | | ---------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------- | | Provides a pictorial or tabular representation of system behavior, helping the tester cover and understand the system effectively. | Cannot be relied on every time — for example, it does not suit systems that are not finite or sequential. | | Lets the tester verify that all conditions are covered and the results are captured. | Requires defining all possible states. This works for small systems but breaks down for larger ones due to the exponential growth in the number of states. | ## FAQs ⚡ What is state transition testing in software testing? State transition testing is a black-box technique that verifies how a system moves between states as input conditions change. It suits finite-state systems where the same input can produce different outputs depending on prior events. 🧩 What are the four parts of a state transition diagram? The four parts are States (conditions the software can be in), Transitions (movement between states), Events (triggers that cause a transition), and Actions (results of a transition, such as a message or output). 🗺️ What is the difference between a state transition diagram and a state table? A state transition diagram uses boxes and arrows and is best for identifying valid transitions. A state table lists states against events in a grid and is best for spotting invalid transitions. 🚫 When should you not use state transition testing? Avoid it when inputs are not sequential or when doing exploratory testing of varied functionalities. It also breaks down for very large systems because the number of states grows exponentially. 🔢 What is 0-switch and 1-switch coverage? 0-switch coverage tests every single valid transition once. 1-switch coverage tests every pair of consecutive transitions. Higher switch coverage finds more sequence-related defects but requires more test cases. 🧪 Is state transition testing a black-box or white-box technique? It is a black-box technique. Test cases are derived from the expected external behavior of states and transitions, without needing knowledge of the internal source code of the application. 🤖 How does AI help generate state transition test cases? AI tools read requirements and automatically build state models, then generate test cases covering valid paths and edge transitions. This reduces manual modeling effort and improves coverage of complex sequences. 🧠 Can AI detect invalid state transitions automatically? Yes. AI can analyze a state model and flag missing, unreachable, or invalid transitions by comparing it against expected behavior patterns, helping testers catch gaps that manual table reviews often miss. #### Summarize this post with: ChatGPT Perplexity Grok Google AI **Stay Updated on AI** **Get Weekly AI Skills, Trends, Actionable Advice.** ##### Sign up for the newsletter Subscribe for Free You have successfully subscribed. 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