State Machine

A state machine dsl for kotlin multi-platform project.

StateMachine let you create and register transitions for a specific state object. Each transition requires a predicate checking the current state of the machine to ensure it's ran at the correct time.

Gradle

Inside the repositories block from your build.gradle file :

maven { url = uri("https://maven.pkg.jetbrains.space/no.beiningbogen/p/stmn/maven") }

Inside dependencies

implementation "no.no.beiningbogen:StateMachine:0.3.0"

Usage

**
* Create and initialize a state machine with a builder lambda.
*/
val stateMachine: StateMachine<CustomerScreenState, CustomerScreenEvents>
= createStateMachine(initialState, dispatcher) {
/**
* Register a predefined transition.
*/
register(loadCustomerTransition)
/**
* Register an anonymous transition here
*/
register {
transition<CustomerScreenState, CustomerScreenEvents.ShowLoading>(
predicate = { !it.isLoading },
execution = { it.value = it.value.copy(isLoading = true) }
)
}
register {
transition<CustomerScreenState, CustomerScreenEvents.HideLoading>(
predicate = { it.isLoading },
execution = { it.value = it.value.copy(isLoading = false) }
)
}
}
...
@Test
fun shouldTransitionToCustomerLoadedState() = dispatcher.runBlockingTest {
val initialState = CustomerScreenState(isLoading = true)
stateMachine = createStateMachine(initialState, dispatcher, builder)
stateMachine.state.test {
assertEquals(initialState, expectItem())
stateMachine.onEvent(CustomerScreenEvents.LoadCustomers)
val nextState = expectItem()
assertTrue(nextState.isLoading)
assertEquals(customers, nextState.customers)
assertNull(nextState.error)
cancelAndIgnoreRemainingEvents()
}
}

More details in StateMachineTest.kt