MemoryView implementation -- tests and remarks

application-arrow/src/commonMain/kotlin/com/fraktalio/fmodel/application/EphemeralViewArrowExtension.kt

@@ -6,9 +6,16 @@ import arrow.core.raise.either
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.fold
 
-
-suspend fun <S, E, Q, MV> MV.handleWithEffect(query: Q): Either<Error, S>
-        where MV : ViewStateComputation<S, E>, MV : EphemeralViewRepository<E, Q> {
+/**
+ * Extension function - Handles the query of type [Q]
+ *
+ * @param query Query of type [Q] to be handled
+ * @return [Either] (either [Error] or State of type [S])
+ *
+ * @author Domenic Cassisi
+ */
+suspend fun <S, E, Q, EV> EV.handleWithEffect(query: Q): Either<Error, S>
+        where EV : ViewStateComputation<S, E>, EV : EphemeralViewRepository<E, Q> {
 
     fun Q.fetchEventsWithEffect(): Either<Error, Flow<E>> =
         either {

application-arrow/src/commonTest/kotlin/com/fraktalio/fmodel/application/EphemeralViewTest.kt

@@ -0,0 +1,86 @@
+package com.fraktalio.fmodel.application
+
+import arrow.core.Either
+import com.fraktalio.fmodel.application.examples.numbers.even.query.EvenNumberEphemeralViewRepository
+import com.fraktalio.fmodel.application.examples.numbers.even.query.evenNumberEphemeralViewRepository
+import com.fraktalio.fmodel.domain.IView
+import com.fraktalio.fmodel.domain.examples.numbers.api.Description
+import com.fraktalio.fmodel.domain.examples.numbers.api.EvenNumberState
+import com.fraktalio.fmodel.domain.examples.numbers.api.NumberValue
+import com.fraktalio.fmodel.domain.examples.numbers.even.query.evenNumberView
+import io.kotest.core.spec.style.FunSpec
+import io.kotest.matchers.shouldBe
+import io.kotest.matchers.types.shouldBeInstanceOf
+
+/**
+ * DSL - Given
+ */
+private suspend fun <S, E, Q> IView<S, E>.given(repository: EphemeralViewRepository<E, Q>, query: () -> Q): Either<Error, S> =
+    EphemeralView(
+        view = this,
+        ephemeralViewRepository = repository
+    ).handleWithEffect(query())
+
+/**
+ * DSL - When
+ */
+private fun <Q> whenQuery(query: Q): Q = query
+
+/**
+ * DSL - Then
+ */
+private infix fun <S> Either<Error, S>.thenState(expected: S) {
+    val state = when (this) {
+        is Either.Right -> value
+        is Either.Left -> throw AssertionError("Expected Either.Right, but found Either.Left with value $value")
+    }
+    state shouldBe expected
+}
+
+private fun <S> Either<Error, S>.thenError() {
+    val error = when (this) {
+        is Either.Right -> throw AssertionError("Expected Either.Left, but found Either.Right with value $value")
+        is Either.Left -> value
+    }
+    error.shouldBeInstanceOf<Error>()
+}
+
+/**
+ * Ephemeral View Test
+ */
+class EphemeralViewTest : FunSpec({
+    val evenView = evenNumberView()
+    val ephemeralViewRepository = evenNumberEphemeralViewRepository() as EvenNumberEphemeralViewRepository
+
+    test("Ephemeral View - load number flow 1") {
+        with(evenView) {
+            given(ephemeralViewRepository) {
+                whenQuery(1)
+            } thenState EvenNumberState(Description("Initial state, Number 2, Number 4"), NumberValue(6))
+        }
+    }
+
+    test("Ephemeral View - load number flow 2") {
+        with(evenView) {
+            given(ephemeralViewRepository) {
+                whenQuery(2)
+            } thenState EvenNumberState(Description("Initial state, Number 4, Number 2"), NumberValue(2))
+        }
+    }
+
+    test("Ephemeral View - load number flow 3 - with error") {
+        with(evenView) {
+            given(ephemeralViewRepository) {
+                whenQuery(3)
+            }.thenError()
+        }
+    }
+
+    test("Ephemeral View - load non-existing number flow") {
+        with(evenView) {
+            given(ephemeralViewRepository) {
+                whenQuery(4)
+            } thenState EvenNumberState(Description("Initial state"), NumberValue(0))
+        }
+    }
+})

application-arrow/src/commonTest/kotlin/com/fraktalio/fmodel/application/examples/numbers/even/query/EvenNumberEphemeralViewRepository.kt

@@ -0,0 +1,44 @@
+package com.fraktalio.fmodel.application.examples.numbers.even.query
+
+import com.fraktalio.fmodel.application.EphemeralViewRepository
+import com.fraktalio.fmodel.domain.examples.numbers.api.Description
+import com.fraktalio.fmodel.domain.examples.numbers.api.NumberEvent
+import com.fraktalio.fmodel.domain.examples.numbers.api.NumberValue
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.emptyFlow
+import kotlinx.coroutines.flow.flowOf
+
+/**
+ * Simple flows of events to represent previously stored events in the event store
+ */
+private var numberFlow1 = flowOf(
+    NumberEvent.EvenNumberEvent.EvenNumberAdded(Description("Number 2"), NumberValue(2)),
+    NumberEvent.EvenNumberEvent.EvenNumberAdded(Description("Number 4"), NumberValue(4))
+)
+
+private var numberFlow2 = flowOf(
+    NumberEvent.EvenNumberEvent.EvenNumberAdded(Description("Number 4"), NumberValue(4)),
+    NumberEvent.EvenNumberEvent.EvenNumberSubtracted(Description("Number 2"), NumberValue(2))
+)
+
+/**
+ * Even number ephemeral view implementation
+ */
+class EvenNumberEphemeralViewRepository : EphemeralViewRepository<NumberEvent.EvenNumberEvent?, Int> {
+
+    override fun Int.fetchEvents(): Flow<NumberEvent.EvenNumberEvent?> {
+        return when (this) {
+            1 -> numberFlow1
+            2 -> numberFlow2
+            3 -> throw RuntimeException("Some fake error while fetching events.")
+            else -> emptyFlow()
+        }
+    }
+
+}
+
+/**
+ * Helper function to create an [EvenNumberEphemeralViewRepository]
+ */
+fun evenNumberEphemeralViewRepository(): EphemeralViewRepository<NumberEvent.EvenNumberEvent?, Int> =
+    EvenNumberEphemeralViewRepository()

application-vanilla/src/commonMain/kotlin/com/fraktalio/fmodel/application/EphemeralViewExtension.kt

@@ -10,5 +10,5 @@ import kotlinx.coroutines.flow.fold
  *
  * @author Domenic Cassisi
  */
-suspend fun <S, E, Q, MV> MV.handle(query: Q): S where MV : ViewStateComputation<S, E>, MV : EphemeralViewRepository<E, Q> =
+suspend fun <S, E, Q, EV> EV.handle(query: Q): S where EV : ViewStateComputation<S, E>, EV : EphemeralViewRepository<E, Q> =
     query.fetchEvents().fold(initialState) { s, e -> evolve(s, e) }

application-vanilla/src/commonTest/kotlin/com/fraktalio/fmodel/application/EphemeralViewTest.kt

@@ -13,16 +13,16 @@ import io.kotest.matchers.shouldBe
 /**
  * DSL - Given
  */
-private suspend fun <S, E, I> IView<S, E>.given(repository: EphemeralViewRepository<E, I>, id: () -> I): S =
+private suspend fun <S, E, Q> IView<S, E>.given(repository: EphemeralViewRepository<E, Q>, query: () -> Q): S =
     EphemeralView(
         view = this,
         ephemeralViewRepository = repository
-    ).handle(id())
+    ).handle(query())
 
 /**
  * DSL - When
  */
-private fun <I> whenId(id: I): I = id
+private fun <Q> whenQuery(query: Q): Q = query
 
 /**
  * DSL - Then
@@ -36,23 +36,23 @@ class EphemeralViewTest : FunSpec({
     test("Ephemeral View - load number flow 1") {
         with(evenView) {
             given(ephemeralViewRepository) {
-                whenId(1)
+                whenQuery(1)
             } thenState EvenNumberState(Description("Initial state, Number 2, Number 4"), NumberValue(6))
         }
     }
 
     test("Ephemeral View - load number flow 2") {
         with(evenView) {
             given(ephemeralViewRepository) {
-                whenId(2)
+                whenQuery(2)
             } thenState EvenNumberState(Description("Initial state, Number 4, Number 2"), NumberValue(2))
         }
     }
 
     test("Ephemeral View - load non-existing number flow") {
         with(evenView) {
             given(ephemeralViewRepository) {
-                whenId(3)
+                whenQuery(3)
             } thenState EvenNumberState(Description("Initial state"), NumberValue(0))
         }
     }