allow state assertions on sagas

fixes #333

examples/bankaccount-jgiven-junit5/src/test/kotlin/SagaStateAssertionTest.kt

@@ -0,0 +1,110 @@
+package io.holixon.axon.testing.examples.jgiven.junit5.kotlin
+
+import com.tngtech.jgiven.annotation.ProvidedScenarioState
+import io.holixon.axon.testing.examples.jgiven.junit5.kotlin.SagaStateAssertionTest.StatefulSaga
+import io.holixon.axon.testing.examples.jgiven.junit5.kotlin.SagaStateAssertionTest.StatefulSaga.Companion.associationProperty
+import io.holixon.axon.testing.jgiven.AxonJGiven
+import io.holixon.axon.testing.jgiven.junit5.SagaFixtureScenarioTest
+import io.toolisticon.testing.jgiven.AND
+import io.toolisticon.testing.jgiven.GIVEN
+import io.toolisticon.testing.jgiven.THEN
+import io.toolisticon.testing.jgiven.WHEN
+import org.assertj.core.api.Assertions.assertThat
+import org.axonframework.modelling.saga.AssociationValue
+import org.axonframework.modelling.saga.EndSaga
+import org.axonframework.modelling.saga.SagaEventHandler
+import org.axonframework.modelling.saga.StartSaga
+import org.junit.jupiter.api.Test
+
+internal class SagaStateAssertionTest : SagaFixtureScenarioTest<StatefulSaga>() {
+
+  data class StartSagaEvent(val key: String)
+  data class IncrementSagaEvent(val key: String, val add: Int)
+  data class EndSagaEvent(val key: String)
+
+  class StatefulSaga {
+    companion object {
+      const val ASSOCIATION_PROPERTY = "key"
+
+      fun associationProperty(key: String) = AssociationValue(ASSOCIATION_PROPERTY, key)
+    }
+
+    lateinit var key: String
+    var state: Int = 0
+
+    @SagaEventHandler(associationProperty = ASSOCIATION_PROPERTY)
+    @StartSaga
+    fun on(evt: StartSagaEvent) {
+      this.key = evt.key
+    }
+
+    @SagaEventHandler(associationProperty = ASSOCIATION_PROPERTY)
+    fun on(evt: IncrementSagaEvent) {
+      this.state += evt.add
+    }
+
+    @SagaEventHandler(associationProperty = ASSOCIATION_PROPERTY)
+    @EndSaga
+    fun on(evt: EndSagaEvent) {
+      this.key = evt.key
+    }
+
+    override fun toString(): String {
+      return "StatefulSaga(key='$key', state=$state)"
+    }
+  }
+
+  @ProvidedScenarioState
+  private val fixture = AxonJGiven.sagaTestFixtureBuilder<StatefulSaga>().build()
+
+  @Test
+  fun `a fresh saga has state 0`() {
+    val key = "123"
+
+    GIVEN.noPriorActivity()
+
+    WHEN
+      .publishing(StartSagaEvent(key))
+
+    THEN
+      .expectActiveSagas(1)
+      .AND
+      .expectSagaState(associationProperty(key), "state is zero") {
+        assertThat(it.state).isEqualTo(0)
+      }
+  }
+
+
+  @Test
+  fun `saga state can be increased`() {
+    val key = "234"
+
+    GIVEN.aggregatePublishedEvent(key, StartSagaEvent(key))
+
+    WHEN
+      .publishing(IncrementSagaEvent(key, 2))
+
+    THEN
+      .expectActiveSagas(1)
+      .AND
+      .expectSagaState(associationProperty(key), "state is two") {
+        assertThat(it.state).isEqualTo(2)
+      }
+  }
+
+  @Test
+  fun `saga can be ended`() {
+    val key = "234"
+
+    GIVEN
+      .aggregatePublishedEvent(key, StartSagaEvent(key))
+      .AND
+      .aggregatePublishedEvent(key, IncrementSagaEvent(key, 2))
+
+    WHEN
+      .publishing(EndSagaEvent(key))
+
+    THEN
+      .expectActiveSagas(0)
+  }
+}

extension/jgiven/core/src/main/kotlin/saga/SagaFixtureGiven.kt

@@ -5,7 +5,9 @@ package io.holixon.axon.testing.jgiven.saga
 import com.tngtech.jgiven.Stage
 import com.tngtech.jgiven.annotation.*
 import io.holixon.axon.testing.jgiven.AxonJGivenStage
+import org.axonframework.modelling.saga.repository.inmemory.InMemorySagaStore
 import org.axonframework.test.saga.FixtureExecutionResult
+import org.axonframework.test.saga.FixtureExecutionResultImpl
 import org.axonframework.test.saga.SagaTestFixture
 import org.axonframework.test.saga.WhenState
 
@@ -25,12 +27,18 @@ class SagaFixtureGiven<T> : Stage<SagaFixtureGiven<T>>() {
   @ProvidedScenarioState
   private lateinit var thenState: FixtureExecutionResult
 
+  @ProvidedScenarioState
+  private lateinit var sagaStore: InMemorySagaStore
+
+  @ProvidedScenarioState
+  private lateinit var sagaType: Class<T>
+
+
   @BeforeStage
   internal fun init() {
-    with(SagaTestFixture::class.java.getDeclaredField("fixtureExecutionResult")) {
-      isAccessible = true
-      thenState = get(fixture) as FixtureExecutionResult
-    }
+    thenState = fixture.fixtureExecutionResult
+    sagaStore = fixture.sagaStore
+    sagaType = fixture.sagaType
   }
 
   /**

extension/jgiven/core/src/main/kotlin/saga/SagaFixtureThen.kt

@@ -5,21 +5,29 @@ package io.holixon.axon.testing.jgiven.saga
 import com.tngtech.jgiven.Stage
 import com.tngtech.jgiven.annotation.As
 import com.tngtech.jgiven.annotation.ExpectedScenarioState
+import com.tngtech.jgiven.annotation.Hidden
 import io.holixon.axon.testing.jgiven.AxonJGivenStage
 import io.holixon.axon.testing.jgiven.step
 import org.axonframework.deadline.DeadlineMessage
 import org.axonframework.eventhandling.EventMessage
+import org.axonframework.modelling.saga.AssociationValue
+import org.axonframework.modelling.saga.repository.inmemory.InMemorySagaStore
 import org.axonframework.test.saga.FixtureExecutionResult
 import org.hamcrest.Matcher
 import java.time.Duration
 import java.time.Instant
 
-
 @AxonJGivenStage
 class SagaFixtureThen<T> : Stage<SagaFixtureThen<T>>() {
 
   @ExpectedScenarioState(required = true)
-  lateinit var thenState: FixtureExecutionResult
+  private lateinit var thenState: FixtureExecutionResult
+
+  @ExpectedScenarioState(required = true)
+  private lateinit var sagaStore: InMemorySagaStore
+
+  @ExpectedScenarioState(required = true)
+  private lateinit var sagaType: Class<T>
 
   /**
    * Expect the given number of Sagas to be active (i.e. ready to respond to incoming events.
@@ -296,4 +304,25 @@ class SagaFixtureThen<T> : Stage<SagaFixtureThen<T>>() {
   fun expectDeadlinesMet(vararg expected: Any): SagaFixtureThen<T> = step {
     thenState.expectTriggeredDeadlines(*expected)
   }
+
+
+  @As("expect saga state: \$description")
+  fun expectSagaState(
+    @Hidden associationValue: AssociationValue,
+    description: String,
+    @Hidden assertion: (T) -> Unit
+  ): SagaFixtureThen<T> = step {
+    assertion(loadSaga(associationValue))
+  }
+
+  private fun loadSaga(associationValue: AssociationValue): T {
+    val sagas: List<T> = sagaStore.findSagas(sagaType, associationValue)
+      .map { sagaKey ->
+        sagaStore.loadSaga(sagaType, sagaKey)
+      }.map { entry -> entry.saga() }
+
+    check(sagas.size == 1) { "Expected exactly one saga for associationProperty=${associationValue.key}, value=${associationValue.value}, but found: ${sagas.size}." }
+
+    return sagas.single()
+  }
 }

extension/jgiven/core/src/main/kotlin/saga/SagaFixtureWhen.kt

@@ -1,4 +1,5 @@
 @file:Suppress("unused")
+
 package io.holixon.axon.testing.jgiven.saga
 
 import com.tngtech.jgiven.Stage
@@ -12,7 +13,6 @@ import org.axonframework.test.saga.WhenState
 import java.time.Duration
 import java.time.Instant
 
-
 /**
  * When stage for saga fixture.
  * @param T aggregate type.

extension/jgiven/core/src/main/kotlin/saga/_reflection.kt

@@ -0,0 +1,31 @@
+package io.holixon.axon.testing.jgiven.saga
+
+import io.holixon.axon.testing.jgiven.saga.SagaTestFixtureFields.fieldFixtureFixtureExecutionResult
+import io.holixon.axon.testing.jgiven.saga.SagaTestFixtureFields.fieldSagaStore
+import io.holixon.axon.testing.jgiven.saga.SagaTestFixtureFields.fieldSagaType
+import org.axonframework.modelling.saga.repository.inmemory.InMemorySagaStore
+import org.axonframework.test.saga.FixtureExecutionResult
+import org.axonframework.test.saga.SagaTestFixture
+import java.lang.reflect.Field
+
+/**
+ * Handles access to private final fields in axon-test.
+ * Might become obsolete when fields are configurable in core.
+ */
+object SagaTestFixtureFields {
+  private val CLASS = SagaTestFixture::class.java
+
+  private fun Class<*>.getDeclaredAccessibleField(fieldName: String): Field = getDeclaredField(fieldName)
+    .apply {
+      isAccessible = true
+    }
+
+  val fieldSagaStore: Field = CLASS.getDeclaredAccessibleField("sagaStore")
+  val fieldFixtureFixtureExecutionResult: Field = CLASS.getDeclaredAccessibleField("fixtureExecutionResult")
+  val fieldSagaType: Field = CLASS.getDeclaredAccessibleField("sagaType")
+}
+
+@Suppress("UNCHECKED_CAST")
+val <T> SagaTestFixture<T>.sagaType: Class<T> get() = fieldSagaType.get(this) as Class<T>
+val <T> SagaTestFixture<T>.fixtureExecutionResult: FixtureExecutionResult get() = fieldFixtureFixtureExecutionResult.get(this) as FixtureExecutionResult
+val <T> SagaTestFixture<T>.sagaStore: InMemorySagaStore get() = fieldSagaStore.get(this) as InMemorySagaStore