til/xstate/start-a-machine-in-a-specific-state.md

Start A Machine In A Specific State

For testing (or debugging) purposes, it can be handy to get an XState machine running from a specific state.

Let's say a machine has an initial state of green and the other states it can be in are yellow and red. And yellow has sub-states of walk and hurry.

By default, a machine will start in the specified initial state.

const service = interpret(trafficLightMachine);

service.start();

service.state.value; //=> 'green'

We can tell the traffic light service to start in the red state instead.

service.start('red');

service.state.value; //=> 'red'

We can even tell it to start in a sub-state (nested state) of a particular state.

service.start({ yellow: 'hurry' });

service.state.value; //=> { yellow: 'hurry' }

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