feat(Android, Stack v5): nested stack uses childFragmentManager of parent container (#3597)

## Description

Closes
<software-mansion/react-native-screens-labs#921>

`StackScreen` implements now `FragmentProviding` interface. This causes
`StackContainer` of nested stack to use `childFragmentManager` of parent
container instead of reusing `supportFragmentManager`.

## Changes

N/A

## Visual documentation

N/A

## Test plan

Not a fix or change in behavior, this is just new behavior.
To verify you need to attach a debugger in `StackContainer` and verify
that it uses
`childFragmentManager` of parent container.

I've added test example for this use case that I'll likely follow
developing in
next PRs.

Author: kkafar

android/src/main/java/com/swmansion/rnscreens/ext/ViewExt.kt

@@ -3,6 +3,8 @@ package com.swmansion.rnscreens.ext
 import android.graphics.drawable.ColorDrawable
 import android.view.View
 import android.view.ViewGroup
+import androidx.fragment.app.Fragment
+import androidx.fragment.app.findFragment
 
 internal fun View.parentAsView() = this.parent as? View
 
@@ -37,3 +39,10 @@ internal fun View.maybeBgColor(): Int? {
 }
 
 internal fun View.asViewGroupOrNull(): ViewGroup? = this as? ViewGroup
+
+internal fun View.findFragmentOrNull(): Fragment? =
+    try {
+        this.findFragment()
+    } catch (_: IllegalStateException) {
+        null
+    }

android/src/main/java/com/swmansion/rnscreens/gamma/stack/screen/StackScreen.kt

@@ -2,16 +2,19 @@ package com.swmansion.rnscreens.gamma.stack.screen
 
 import android.annotation.SuppressLint
 import android.view.ViewGroup
+import androidx.fragment.app.Fragment
 import androidx.lifecycle.LifecycleOwner
 import com.facebook.react.uimanager.ThemedReactContext
+import com.swmansion.rnscreens.ext.findFragmentOrNull
+import com.swmansion.rnscreens.gamma.common.FragmentProviding
 import com.swmansion.rnscreens.gamma.stack.host.StackHost
 import java.lang.ref.WeakReference
 import kotlin.properties.Delegates
 
 @SuppressLint("ViewConstructor") // should never be restored
 class StackScreen(
     private val reactContext: ThemedReactContext,
-) : ViewGroup(reactContext) {
+) : ViewGroup(reactContext), FragmentProviding {
     enum class ActivityMode {
         DETACHED,
         ATTACHED,
@@ -65,4 +68,8 @@ class StackScreen(
         r: Int,
         b: Int,
     ) = Unit
+
+    override fun getAssociatedFragment(): Fragment? = this.findFragmentOrNull()?.also {
+        check(it is StackScreenFragment) { "[RNScreens] Unexpected fragment type: ${it.javaClass.simpleName}"}
+    }
 }

apps/src/tests/issue-tests/TestStackNesting.tsx

@@ -0,0 +1,89 @@
+import React from 'react';
+
+import {
+  StackContainer,
+  StackRouteConfig,
+  useStackNavigationContext,
+} from '../../shared/gamma/containers/stack';
+import { Button, Text, View } from 'react-native';
+
+function TemplateScreen() {
+  const navigation = useStackNavigationContext();
+
+  return (
+    <View
+      style={{ flex: 1, backgroundColor: 'white', justifyContent: 'center' }}>
+      <Text>Route: {navigation.routeKey}</Text>
+      <Button title="Push A" onPress={() => navigation.push('A')} />
+      <Button title="Push B" onPress={() => navigation.push('B')} />
+      <Button
+        title="Push NestedStack"
+        onPress={() => navigation.push('NestedStack')}
+      />
+      <Button title="Pop" onPress={() => navigation.pop(navigation.routeKey)} />
+      <Button title="Preload A" onPress={() => navigation.preload('A')} />
+      <Button title="Preload B" onPress={() => navigation.preload('B')} />
+    </View>
+  );
+}
+
+function NestedTemplateScreen() {
+  const navigation = useStackNavigationContext();
+
+  return (
+    <View
+      style={{ flex: 1, backgroundColor: 'white', justifyContent: 'center' }}>
+      <Text>Route: {navigation.routeKey}</Text>
+      <Button title="Push NestedA" onPress={() => navigation.push('NestedA')} />
+      <Button title="Push NestedB" onPress={() => navigation.push('NestedB')} />
+      <Button title="Pop" onPress={() => navigation.pop(navigation.routeKey)} />
+      <Button
+        title="Preload NestedA"
+        onPress={() => navigation.preload('NestedA')}
+      />
+      <Button
+        title="Preload NestedB"
+        onPress={() => navigation.preload('NestedB')}
+      />
+    </View>
+  );
+}
+
+function NestedStackScreen() {
+  return <StackContainer routeConfigs={ROUTE_CONFIGS_NESTED_STACK} />;
+}
+
+const ROUTE_CONFIGS: StackRouteConfig[] = [
+  {
+    name: 'A',
+    Component: TemplateScreen,
+    options: {},
+  },
+  {
+    name: 'B',
+    Component: TemplateScreen,
+    options: {},
+  },
+  {
+    name: 'NestedStack',
+    Component: NestedStackScreen,
+    options: {},
+  },
+];
+
+const ROUTE_CONFIGS_NESTED_STACK: StackRouteConfig[] = [
+  {
+    name: 'NestedA',
+    Component: NestedTemplateScreen,
+    options: {},
+  },
+  {
+    name: 'NestedB',
+    Component: NestedTemplateScreen,
+    options: {},
+  },
+];
+
+export default function App() {
+  return <StackContainer routeConfigs={ROUTE_CONFIGS} />;
+}

apps/src/tests/issue-tests/index.ts

@@ -199,3 +199,4 @@ export { default as TestBottomTabsOrientation } from './TestBottomTabsOrientatio
 export { default as TestScreenStack } from './TestScreenStack';
 export { default as TestSplit } from './TestSplit';
 export { default as TestSafeAreaViewIOS } from './TestSafeAreaViewIOS';
+export { default as TestStackNesting } from './TestStackNesting';