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Allow split state definitions #29

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Allow split state definitions #29

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ced1bdf
add a test for a state machine with split state definitions
SpaceBison Jun 3, 2020
81156c1
honor all state definitions instead of only the first one
SpaceBison Jun 3, 2020
faee9b0
reintroduce an error when no valid state definitions were found
SpaceBison Jun 3, 2020
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9 changes: 8 additions & 1 deletion src/main/kotlin/com/tinder/StateMachine.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -51,7 +51,14 @@ class StateMachine<STATE : Any, EVENT : Any, SIDE_EFFECT : Any> private construc
private fun STATE.getDefinition() = graph.stateDefinitions
.filter { it.key.matches(this) }
.map { it.value }
.firstOrNull() ?: error("Missing definition for state ${this.javaClass.simpleName}!")
.also { if (it.isEmpty()) error("Missing definition for state ${this.javaClass.simpleName}!") }
.fold(Graph.State<STATE, EVENT, SIDE_EFFECT>()) { acc, state ->
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I like this change, this also works when we want to have a generic transition

private val stateMachine = StateMachine.create<String, Int, Nothing> {
                initialState(STATE_A)
                state(STATE_A) {
                    on(EVENT_1) {
                        transitionTo(STATE_B)
                    }
                }
                state(STATE_B) {
                    on(EVENT_2) {
                        transitionTo(STATE_A)
                    }
                }
                state<String> {
                    on(EVENT_3) {
                        transitionTo(STATE_C)
                    }
                }
            }

for example, this one, having state<String> or state(any()) we can move from any state to another state with the same event.

acc.apply {
onEnterListeners.addAll(state.onEnterListeners)
onExitListeners.addAll(state.onExitListeners)
transitions.putAll(state.transitions)
}
}

private fun STATE.notifyOnEnter(cause: EVENT) {
getDefinition().onEnterListeners.forEach { it(this, cause) }
Expand Down
78 changes: 77 additions & 1 deletion src/test/kotlin/com/tinder/StateMachineTest.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -719,6 +719,83 @@ internal class StateMachineTest {
}
}

class WithSplitStateDefinition {
private val firstDefinitionOnEnterListener = mock<String.(Int) -> Unit>()
private val secondDefinitionOnEnterListener = mock<String.(Int) -> Unit>()
private val firstDefinitionOnExitListener = mock<String.(Int) -> Unit>()
private val secondDefinitionOnExitListener = mock<String.(Int) -> Unit>()

private val stateMachine = StateMachine.create<String, Int, Nothing> {
initialState(STATE_A)

state(STATE_A) {
on(EVENT_1) {
transitionTo(STATE_B)
}

onExit(firstDefinitionOnExitListener)
}

state(STATE_A) {
on(EVENT_2) {
transitionTo(STATE_B)
}

onExit(secondDefinitionOnExitListener)
}

state(STATE_B) {
onEnter(firstDefinitionOnEnterListener)
}

state(STATE_B) {
onEnter(secondDefinitionOnEnterListener)
}
}

@Test
fun transition_givenFirstDefinitionEvent_shouldReturnValidTransition() {
// When
val transition = stateMachine.transition(EVENT_1)

// Then
assertThat(transition).isEqualTo(
StateMachine.Transition.Valid<String, Int, String>(STATE_A, EVENT_1, STATE_B, null)
)
}

@Test
fun transition_givenSecondDefinitionEvent_shouldReturnValidTransition() {
// When
val transition = stateMachine.transition(EVENT_2)

// Then
assertThat(transition).isEqualTo(
StateMachine.Transition.Valid<String, Int, String>(STATE_A, EVENT_2, STATE_B, null)
)
}

@Test
fun transition_givenValidEvent_shouldTriggerOnExitListeners() {
// When
stateMachine.transition(EVENT_1)

// Then
then(firstDefinitionOnExitListener).should().invoke(STATE_A, EVENT_1)
then(secondDefinitionOnExitListener).should().invoke(STATE_A, EVENT_1)
}

@Test
fun transition_givenValidEvent_shouldTriggerOnEnterListeners() {
// When
stateMachine.transition(EVENT_1)

// Then
then(firstDefinitionOnEnterListener).should().invoke(STATE_B, EVENT_1)
then(secondDefinitionOnEnterListener).should().invoke(STATE_B, EVENT_1)
}
}

private companion object {
private const val STATE_A = "a"
private const val STATE_B = "b"
Expand All @@ -733,5 +810,4 @@ internal class StateMachineTest {
private const val SIDE_EFFECT_1 = "alpha"
}
}

}