Move FakeCacheService to the preferences test module

The fake was declared in RootFlowNodeTest, so other tests could not use
it. Move it next to the API it fakes, and let the cleared cache event
flow be provided by the caller, so that a test can emit events.

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

appnav/build.gradle.kts

@@ -75,6 +75,7 @@ dependencies {
     testImplementation(projects.features.forward.test)
     testImplementation(projects.features.messages.test)
     testImplementation(projects.features.networkmonitor.test)
+    testImplementation(projects.features.preferences.test)
     testImplementation(projects.features.rageshake.test)
     testImplementation(projects.features.signedout.test)
     testImplementation(projects.services.apperror.test)

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

@@ -35,7 +35,7 @@ import io.element.android.features.login.api.LoginParams
 import io.element.android.features.login.api.accesscontrol.AccountProviderAccessControl
 import io.element.android.features.login.test.FakeLoginEntryPoint
 import io.element.android.features.login.test.FakeLoginIntentResolver
-import io.element.android.features.preferences.api.CacheService
+import io.element.android.features.preferences.test.FakeCacheService
 import io.element.android.features.rageshake.test.FakeBugReportEntryPoint
 import io.element.android.features.rageshake.test.logs.FakeAnnouncementService
 import io.element.android.features.share.test.FakeShareIntentHandler
@@ -47,7 +47,6 @@ import io.element.android.libraries.architecture.Presenter
 import io.element.android.libraries.di.DependencyInjectionGraphOwner
 import io.element.android.libraries.featureflag.test.FakeFeatureFlagService
 import io.element.android.libraries.matrix.api.MatrixClient
-import io.element.android.libraries.matrix.api.core.SessionId
 import io.element.android.libraries.matrix.test.FakeSdkMetadata
 import io.element.android.libraries.matrix.test.auth.FakeMatrixAuthenticationService
 import io.element.android.libraries.matrix.test.permalink.FakePermalinkParser
@@ -65,7 +64,6 @@ import io.element.android.tests.testutils.robolectric.RobolectricTest
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.flow.FlowCollector
-import kotlinx.coroutines.flow.emptyFlow
 import kotlinx.coroutines.test.TestScope
 import kotlinx.coroutines.test.runCurrent
 import kotlinx.coroutines.test.runTest
@@ -208,10 +206,6 @@ private class NotUsedPresenter<T> : Presenter<T> {
     override fun present(): T = error("Not used")
 }
 
-private class FakeCacheService : CacheService {
-    override val clearedCacheEventFlow = emptyFlow<SessionId>()
-}
-
 private class FakeSyncOrchestratorFactory : SyncOrchestrator.Factory {
     override fun create(matrixClient: MatrixClient, sessionCoroutineScope: CoroutineScope): SyncOrchestrator = error("Not used")
 }

features/preferences/test/build.gradle.kts

@@ -16,5 +16,7 @@ android {
 dependencies {
     implementation(projects.libraries.architecture)
     implementation(projects.features.preferences.api)
+    implementation(projects.libraries.matrix.api)
+    implementation(libs.coroutines.core)
     implementation(projects.tests.testutils)
 }

features/preferences/test/src/main/kotlin/io/element/android/features/preferences/test/FakeCacheService.kt

@@ -0,0 +1,17 @@
+/*
+ * Copyright (c) 2026 Element Creations Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
+ * Please see LICENSE files in the repository root for full details.
+ */
+
+package io.element.android.features.preferences.test
+
+import io.element.android.features.preferences.api.CacheService
+import io.element.android.libraries.matrix.api.core.SessionId
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.emptyFlow
+
+class FakeCacheService(
+    override val clearedCacheEventFlow: Flow<SessionId> = emptyFlow(),
+) : CacheService