CupertinoSliverRefreshControl inactive overscroll behavior (#27588)

packages/flutter/lib/src/cupertino/refresh.dart

@@ -520,7 +520,7 @@ class _CupertinoSliverRefreshControlState extends State<CupertinoSliverRefreshCo
         builder: (BuildContext context, BoxConstraints constraints) {
           latestIndicatorBoxExtent = constraints.maxHeight;
           refreshState = transitionNextState();
-          if (widget.builder != null && refreshState != RefreshIndicatorMode.inactive) {
+          if (widget.builder != null && latestIndicatorBoxExtent > 0) {
             return widget.builder(
               context,
               refreshState,

packages/flutter/test/cupertino/refresh_test.dart

@@ -38,16 +38,9 @@ void main() {
     when(mockHelper.builder(
             any, any, any, any, any))
         .thenAnswer((Invocation i) {
-      final RefreshIndicatorMode refreshState = i.positionalArguments[1];
       final double pulledExtent = i.positionalArguments[2];
       final double refreshTriggerPullDistance = i.positionalArguments[3];
       final double refreshIndicatorExtent = i.positionalArguments[4];
-      if (refreshState == RefreshIndicatorMode.inactive) {
-        throw TestFailure(
-          'RefreshControlIndicatorBuilder should never be called with the '
-          "inactive state because there's nothing to build in that case"
-        );
-      }
       if (pulledExtent < 0.0) {
         throw TestFailure('The pulledExtent should never be less than 0.0');
       }
@@ -535,6 +528,94 @@ void main() {
       debugDefaultTargetPlatformOverride = null;
     });
 
+    testWidgets('builder still called when sliver snapped back more than 90%', (WidgetTester tester) async {
+      debugDefaultTargetPlatformOverride = TargetPlatform.iOS;
+
+      refreshIndicator = const Center(child: Text('-1'));
+
+      await tester.pumpWidget(
+        Directionality(
+          textDirection: TextDirection.ltr,
+          child: CustomScrollView(
+            slivers: <Widget>[
+              CupertinoSliverRefreshControl(
+                builder: builder,
+                onRefresh: onRefresh,
+              ),
+              buildAListOfStuff(),
+            ],
+          ),
+        ),
+      );
+
+      await tester.drag(find.text('0'), const Offset(0.0, 150.0));
+      await tester.pump();
+      verify(mockHelper.builder(
+        any,
+        RefreshIndicatorMode.armed,
+        150.0,
+        100.0, // Default value.
+        60.0, // Default value.
+      ));
+      expect(
+        tester.getRect(find.widgetWithText(Center, '-1')),
+        Rect.fromLTRB(0.0, 0.0, 800.0, 150.0),
+      );
+      verify(mockHelper.refreshTask());
+
+      // Rebuilds the sliver with a layout extent now.
+      await tester.pump();
+      // Let it snap back to occupy the indicator's final sliver space only.
+      await tester.pump(const Duration(seconds: 2));
+      verify(mockHelper.builder(
+        any,
+        RefreshIndicatorMode.refresh,
+        60.0,
+        100.0, // Default value.
+        60.0, // Default value.
+      ));
+      expect(
+        tester.getRect(find.widgetWithText(Center, '-1')),
+        Rect.fromLTRB(0.0, 0.0, 800.0, 60.0),
+      );
+      expect(
+        tester.getRect(find.widgetWithText(Center, '0')),
+        Rect.fromLTRB(0.0, 60.0, 800.0, 260.0),
+      );
+
+      refreshCompleter.complete(null);
+      await tester.pump();
+      verify(mockHelper.builder(
+        any,
+        RefreshIndicatorMode.done,
+        60.0,
+        100.0, // Default value.
+        60.0, // Default value.
+      ));
+
+      // Waiting for refresh control to reach approximately 5% of height
+      await tester.pump(const Duration(milliseconds: 400));
+
+      expect(
+        tester.getRect(find.widgetWithText(Center, '0')).top,
+        moreOrLessEquals(3.0, epsilon: 4e-1),
+      );
+      expect(
+        tester.getRect(find.widgetWithText(Center, '-1')).height,
+        moreOrLessEquals(3.0, epsilon: 4e-1),
+      );
+      verify(mockHelper.builder(
+        any,
+        RefreshIndicatorMode.inactive,
+        2.6980688300546443, // ~5% of 60.0
+        100.0, // Default value.
+        60.0, // Default value.
+      ));
+      expect(find.text('-1'), findsOneWidget);
+
+      debugDefaultTargetPlatformOverride = null;
+    });
+
     testWidgets(
       'retracting sliver during done cannot be pulled to refresh again until fully retracted',
       (WidgetTester tester) async {