Chapter 4 – Test Analysis & Design
State Diagram – ISTQB Definition
Last Updated: July 12, 2026 · SoftwareTestPilot QA Team
Official ISTQB Definition
A diagram that depicts the states that a component or system can assume, and shows the events or circumstances that cause and/or result from a change from one state to another.
In simple words
A picture of all the modes the system can be in and the arrows showing how it switches between them.
Exam tip
State diagrams are the source model for state transition testing — memorize the notation (states, transitions, events, actions).
Related terms
- State Transition TestingYou model the system as states (Logged Out, Logged In, Locked) and design tests that trigger valid and invalid transitions between them.
- State TableA table version of a state diagram — rows are states, columns are events, cells are the next state (or 'invalid').
- Use Case TestingTake a real user journey — like ‘checkout with a coupon’ — and turn each main and alternative flow into a test case.
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