Fourth black box testing technique is state transition tables

This technique is used where tester views a software in terms of state, transition between states ,the inputs or events that trigger state, changes(transition) and actions which may result from those transitions.

Invalid states are those which cant be reached from one state.

The circles will denote the states and the arrows will denote the actions that lead to those states in the state transtion diagram

Like let take an example of a ticket booking site. Here there can be various states for a tickets.

First state is when we search a ticket. Then if we like the ticket we can pay for it and then after paying the state of ticket changes to paid.

Then the system will issue us the ticket and the state of ticket changes to issued .

From there we can print the ticket and state changes to printed or we can cancel the ticket and state changes to cancelled.

Invalid state can be something like if the site doesn’t allow us to cancel the ticket after issue state then going to cancel after issue will be an invalid state.

Importance of state transition diagram is that they are business centric. Here we are not looking at a webpage or entering data and checking results etc. Here we are just figuring out how a end to end business scenario will work out.

So let us say we have less time.

We can just test 2,3 flows

Like search tcket ->paid->issued ->printed etc.

Or search ticket->Cancel

If these 2 flows work then instead of testing other flows we can just be confident that site will work for those flows as well.

Like search ->paid->cancel.