fix(firebase_ui_database): Perform list operations in correct order

packages/firebase_ui_database/lib/src/query_builder.dart

@@ -187,20 +187,18 @@ class _FirestoreQueryBuilderState extends State<FirebaseDatabaseQueryBuilder> {
             _snapshot = _snapshot.copyWith(isFetching: false);
           }
 
-          List<DataSnapshot> docs;
-          if (event.snapshot.children.length < expectedDocsCount) {
-            docs = event.snapshot.children.toList();
-          } else {
-            docs = event.snapshot.children.take(expectedDocsCount - 1).toList();
+          Iterable<DataSnapshot> docs = event.snapshot.children;
+          if (widget.reverseQuery) {
+            docs = docs.toList().reversed;
           }
 
-          if (widget.reverseQuery) {
-            docs = docs.reversed.toList();
+          if (event.snapshot.children.length >= expectedDocsCount) {
+            docs = docs.take(expectedDocsCount - 1);
           }
 
           _snapshot = _snapshot.copyWith(
             hasData: true,
-            docs: docs,
+            docs: docs.toList(),
             error: null,
             hasMore: event.snapshot.children.length == expectedDocsCount,
             stackTrace: null,

tests/integration_test/firebase_ui_database/database_list_view_test.dart

@@ -201,6 +201,56 @@ void main() {
         }
       },
     );
+
+    testWidgets(
+      'Allows reversing the database query',
+      (tester) async {
+        final ref = rtdb.ref().child(_kTestPath);
+
+        await fillReference(ref, 25);
+        late double size;
+
+        await tester.pumpWidget(
+          MaterialApp(
+            home: Material(
+              child: Builder(builder: (context) {
+                final mq = MediaQuery.of(context);
+                final h = mq.size.height;
+                size = h / 5;
+
+                return FirebaseDatabaseListView(
+                  physics: const ClampingScrollPhysics(),
+                  query: ref.orderByValue(),
+                  reverseQuery: true,
+                  cacheExtent: 0,
+                  pageSize: 5,
+                  itemExtent: size,
+                  itemBuilder: (context, snapshot) {
+                    final v = snapshot.value as int;
+
+                    return Container(
+                      alignment: Alignment.center,
+                      color: Colors.black.withAlpha(v % 2 == 0 ? 50 : 100),
+                      key: ValueKey(v.toString()),
+                      child: Text(
+                        v.toString(),
+                        textAlign: TextAlign.center,
+                      ),
+                    );
+                  },
+                );
+              }),
+            ),
+          ),
+        );
+
+        await tester.pumpAndSettle();
+
+        for (int i = 24; i >= 20; i--) {
+          expect(find.byKey(ValueKey(i.toString())), findsOneWidget);
+        }
+      },
+    );
   });
 }
 
@@ -221,4 +271,4 @@ Future<void> fillReference(DatabaseReference ref, int length) {
   return Future.wait([
     for (var i = 0; i < length; i++) ref.push().set(i),
   ]);
-}
+}

tests/ios/Flutter/AppFrameworkInfo.plist

@@ -21,6 +21,6 @@
   <key>CFBundleVersion</key>
   <string>1.0</string>
   <key>MinimumOSVersion</key>
-  <string>11.0</string>
+  <string>12.0</string>
 </dict>
 </plist>

tests/ios/Runner.xcodeproj/project.pbxproj

@@ -474,7 +474,7 @@
 				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
 				GCC_WARN_UNUSED_FUNCTION = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
-				IPHONEOS_DEPLOYMENT_TARGET = 11.0;
+				IPHONEOS_DEPLOYMENT_TARGET = 12.0;
 				MTL_ENABLE_DEBUG_INFO = NO;
 				SDKROOT = iphoneos;
 				SUPPORTED_PLATFORMS = iphoneos;
@@ -602,7 +602,7 @@
 				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
 				GCC_WARN_UNUSED_FUNCTION = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
-				IPHONEOS_DEPLOYMENT_TARGET = 11.0;
+				IPHONEOS_DEPLOYMENT_TARGET = 12.0;
 				MTL_ENABLE_DEBUG_INFO = YES;
 				ONLY_ACTIVE_ARCH = YES;
 				SDKROOT = iphoneos;
@@ -651,7 +651,7 @@
 				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
 				GCC_WARN_UNUSED_FUNCTION = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
-				IPHONEOS_DEPLOYMENT_TARGET = 11.0;
+				IPHONEOS_DEPLOYMENT_TARGET = 12.0;
 				MTL_ENABLE_DEBUG_INFO = NO;
 				SDKROOT = iphoneos;
 				SUPPORTED_PLATFORMS = iphoneos;