Merge pull request #71 from isaac-udy/viewmodel-results-lifecycle-bug

Revert to using `addObserver` instead of `launchWhenCreated` in `LazyEnroResultChannel`

enro-core/src/main/java/dev/enro/core/EnroExceptions.kt

@@ -0,0 +1,5 @@
+package dev.enro.core
+
+abstract class EnroException(message: String) : IllegalStateException(message)
+
+class EnroLifecycleException(message: String) : EnroException(message)

enro-core/src/main/java/dev/enro/core/result/internal/LazyResultChannelProperty.kt

@@ -2,7 +2,10 @@ package dev.enro.core.result.internal
 
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.FragmentActivity
-import androidx.lifecycle.*
+import androidx.lifecycle.Lifecycle
+import androidx.lifecycle.LifecycleEventObserver
+import androidx.lifecycle.LifecycleOwner
+import dev.enro.core.EnroLifecycleException
 import dev.enro.core.NavigationHandle
 import dev.enro.core.getNavigationHandle
 import dev.enro.core.result.EnroResultChannel
@@ -29,17 +32,22 @@ internal class LazyResultChannelProperty<T>(
         val lifecycleOwner = owner as LifecycleOwner
         val lifecycle = lifecycleOwner.lifecycle
 
-        lifecycle.coroutineScope.launchWhenCreated {
-            resultChannel = ResultChannelImpl(
-                navigationHandle = handle.value,
-                resultType = resultType,
-                onResult = onResult
-            ).managedByLifecycle(lifecycle)
-        }
+        lifecycle.addObserver(object : LifecycleEventObserver {
+            override fun onStateChanged(source: LifecycleOwner, event: Lifecycle.Event) {
+                if (event != Lifecycle.Event.ON_CREATE) return;
+                resultChannel = ResultChannelImpl(
+                    navigationHandle = handle.value,
+                    resultType = resultType,
+                    onResult = onResult
+                ).managedByLifecycle(lifecycle)
+            }
+        })
     }
 
     override fun getValue(
         thisRef: Any,
         property: KProperty<*>
-    ): EnroResultChannel<T> = resultChannel!!
+    ): EnroResultChannel<T> = resultChannel ?: throw EnroLifecycleException(
+        "LazyResultChannelProperty's EnroResultChannel is not initialised. Are you attempting to use the result channel before the result channel's lifecycle owner has entered the CREATED state?"
+    )
 }

enro-core/src/main/java/dev/enro/viewmodel/EnroViewModelFactory.kt

@@ -2,6 +2,7 @@ package dev.enro.viewmodel
 
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.ViewModelProvider
+import dev.enro.core.EnroException
 import dev.enro.core.NavigationHandle
 
 @PublishedApi
@@ -15,6 +16,7 @@ internal class EnroViewModelFactory(
         val viewModel = try {
             delegate.create(modelClass) as T
         } catch (ex: RuntimeException) {
+            if(ex is EnroException) throw ex
             throw RuntimeException("Failed to created ${modelClass.name} using factory ${delegate::class.java.name}.\n" +
                     "This can occur if you are using an @HiltViewModel annotated ViewModel, but are not requesting the ViewModel from inside an @AndroidEntryPoint annotated Activity/Fragment.", ex)
         }

enro/src/androidTest/java/dev/enro/result/ViewModelResultTests.kt

@@ -0,0 +1,120 @@
+package dev.enro.result
+
+import android.os.Bundle
+import android.view.View
+import androidx.lifecycle.ViewModel
+import androidx.test.core.app.ActivityScenario
+import dev.enro.*
+import dev.enro.annotations.NavigationDestination
+import dev.enro.core.NavigationKey
+import dev.enro.core.forward
+import dev.enro.core.result.closeWithResult
+import dev.enro.core.result.registerForNavigationResult
+import dev.enro.expectFragment
+import dev.enro.viewmodel.enroViewModels
+import dev.enro.viewmodel.navigationHandle
+import kotlinx.parcelize.Parcelize
+import org.junit.Assert.assertEquals
+import org.junit.Test
+
+class ViewModelResultTests {
+    @Test
+    fun givenOrchestratedResultFlowManagedByViewModels_whenOrchestratedResultFlowExecutes_thenResultsAreReceivedCorrectly() {
+        ActivityScenario.launch(DefaultActivity::class.java)
+            .getNavigationHandle<NavigationKey>()
+            .forward(OrchestratorKey())
+
+        expectFragment<OrchestratorFragment>()
+            .viewModel
+            .let {
+                assertEquals("FirstStep -> SecondStep(SecondStepNested)", it.currentResult)
+            }
+    }
+}
+
+
+@Parcelize
+class OrchestratorKey : NavigationKey
+
+class OrchestratorViewModel : ViewModel() {
+    var currentResult = ""
+
+    val navigation by navigationHandle<NavigationKey>()
+    val resultOne by registerForNavigationResult<String>(navigation) {
+        currentResult = it
+        resultTwo.open(SecondStepKey())
+    }
+    val resultTwo by registerForNavigationResult<String>(navigation) {
+        currentResult = "$currentResult -> $it"
+    }
+
+    init {
+        resultOne.open(FirstStepKey())
+    }
+}
+
+@NavigationDestination(OrchestratorKey::class)
+class OrchestratorFragment : TestFragment() {
+    val viewModel by enroViewModels<OrchestratorViewModel>()
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        viewModel.hashCode()
+    }
+}
+
+@Parcelize
+class FirstStepKey : NavigationKey.WithResult<String>
+
+class FirstStepViewModel : ViewModel() {
+    private val navigation by navigationHandle<FirstStepKey>()
+    init {
+        navigation.closeWithResult("FirstStep")
+    }
+}
+
+@NavigationDestination(FirstStepKey::class)
+class FirstStepFragment : TestFragment() {
+    private val viewModel by enroViewModels<FirstStepViewModel>()
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        viewModel.hashCode()
+    }
+}
+
+@Parcelize
+class SecondStepKey : NavigationKey.WithResult<String>
+
+class SecondStepViewModel : ViewModel() {
+    private val navigation by navigationHandle<SecondStepKey>()
+    private val nested by registerForNavigationResult<String>(navigation) {
+        navigation.closeWithResult("SecondStep($it)")
+    }
+    init {
+        nested.open(SecondStepNestedKey())
+    }
+}
+
+@NavigationDestination(SecondStepKey::class)
+class SecondStepFragment : TestFragment() {
+    private val viewModel by enroViewModels<SecondStepViewModel>()
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        viewModel.hashCode()
+    }
+}
+
+
+@Parcelize
+class SecondStepNestedKey : NavigationKey.WithResult<String>
+
+class SecondStepNestedViewModel : ViewModel() {
+    private val navigation by navigationHandle<SecondStepNestedKey>()
+    init {
+        navigation.closeWithResult("SecondStepNested")
+    }
+}
+
+@NavigationDestination(SecondStepNestedKey::class)
+class SecondStepNestedFragment : TestFragment() {
+    private val viewModel by enroViewModels<SecondStepNestedViewModel>()
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        viewModel.hashCode()
+    }
+}