Move FakeParentNode to the testutils module

The fake was declared in RootFlowNodeTest, so other tests could not use
it. Move it to the testutils module, in the node package, and make its
documentation generic.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

appnav/src/test/kotlin/io/element/android/appnav/RootFlowNodeTest.kt

@@ -12,13 +12,8 @@ package io.element.android.appnav
 import android.content.Intent
 import android.net.Uri
 import androidx.arch.core.executor.testing.InstantTaskExecutorRule
-import androidx.compose.runtime.Composable
-import androidx.compose.ui.Modifier
 import com.bumble.appyx.core.modality.AncestryInfo
 import com.bumble.appyx.core.modality.BuildContext
-import com.bumble.appyx.core.navigation.model.permanent.PermanentNavModel
-import com.bumble.appyx.core.node.Node
-import com.bumble.appyx.core.node.ParentNode
 import com.bumble.appyx.core.node.node
 import com.bumble.appyx.navmodel.backstack.activeElement
 import com.bumble.appyx.testing.junit4.util.MainDispatcherRule
@@ -42,7 +37,6 @@ import io.element.android.features.share.test.FakeShareIntentHandler
 import io.element.android.features.signedout.test.FakeSignedOutEntryPoint
 import io.element.android.libraries.accountselect.test.FakeAccountSelectEntryPoint
 import io.element.android.libraries.architecture.AssistedNodeFactory
-import io.element.android.libraries.di.DependencyInjectionGraphOwner
 import io.element.android.libraries.featureflag.test.FakeFeatureFlagService
 import io.element.android.libraries.matrix.test.FakeSdkMetadata
 import io.element.android.libraries.matrix.test.auth.FakeMatrixAuthenticationService
@@ -57,6 +51,7 @@ import io.element.android.services.analytics.test.FakeAnalyticsService
 import io.element.android.services.analytics.test.watchers.FakeAnalyticsColdStartWatcher
 import io.element.android.services.apperror.test.FakeAppErrorStateService
 import io.element.android.tests.testutils.node.FakeNodeFactoriesBindings
+import io.element.android.tests.testutils.node.FakeParentNode
 import io.element.android.tests.testutils.presenter.NotUsedPresenter
 import io.element.android.tests.testutils.robolectric.RobolectricTest
 import kotlinx.coroutines.ExperimentalCoroutinesApi
@@ -192,20 +187,3 @@ private val A_LOGIN_ENTRY_POINT_PARAMS = LoginEntryPoint.Params(
     accountProvider = A_LOGIN_PARAMS.accountProvider,
     loginHint = A_LOGIN_PARAMS.loginHint,
 )
-
-/**
- * [RootFlowNode] creates its children using the dependency injection graph of its ancestors, so it needs a parent
- * owning a graph able to create a [NotLoggedInFlowNode].
- */
-private class FakeParentNode(
-    override val graph: Any,
-) : ParentNode<Unit>(
-    navModel = PermanentNavModel(navTargets = setOf(Unit), savedStateMap = null),
-    buildContext = BuildContext.root(savedStateMap = null),
-),
-    DependencyInjectionGraphOwner {
-    override fun resolve(navTarget: Unit, buildContext: BuildContext): Node = node(buildContext) {}
-
-    @Composable
-    override fun View(modifier: Modifier) = Unit
-}