State Transition Testing

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State transition testing is a technique to test software by using a state diagram or a state table to represent the states of the software and the valid transitions between them. Starting from the initial state, you test each state transition and test the next state, until you reach a final state or the initial state. You test how the software behaves with different event sequences. State transition testing is based on software requirements and technical specifications.

State Transition Testing Examples

• You test a login feature. You use a state diagram or a state table to show the states of the system, such as logged out, logged in, and locked out. Starting from the logged out state, you test each valid state transition.
• You test a money transfer feature. You use a state diagram or a state table to show the states of the system, such as account selected, amount entered, confirmed, and completed. You test each valid state transition. You also test that any invalid state transition, such as completed to confirmed is impossible.
  
• You test a flight booking feature. You use a state transition diagram or a state table to show the states of the system, such as destination selected, date selected, seat selected, payment made, and confirmation sent. You test that each valid state transition is possible and each invalid state transition is impossible
• You test a calculator feature. You use a diagram or a table to show the states of the system, such as first number entered, operator entered, result displayed, or error displayed. You test each state transition from the initial state to a final state (result displayed, or error displayed).

Tips for State Transition Testing

• Identify the states and transitions of the system using the software requirements, use cases, flowcharts, etc.
• Test both valid and invalid state transitions to know if the system handles them appropriately.
• Test the relevant workflows of the system that depend on the states and transitions in the state diagram or state table.
• Use tools to automate tasks, such as generating state table, executing tests, and reporting results.

FAQ (interview questions and answers)

1. What is the purpose of state transition testing?
   The purpose of state transition testing is to test systems that behave based on their previous state or input history.
2. What is the advantage of state transition testing?
   It can show the system behavior in a visual manner. It can help to cover all given states and valid transitions.
3. What is the disadvantage of state transition testing?
   It can be complex to create and maintain state diagrams or state tables for large and complex systems. It can be hard to trace the test cases back to the requirements.
4. Is state transition testing a type of black-box testing?
   Yes, it is a technique that can help test the software without using the knowledge of its code or structure.

Remember to just comment if you have any doubts or queries.