sliverGridDelegate mainAxisExtent add assert

Author: hello-coder-xu

packages/flutter/lib/src/rendering/sliver_grid.dart

@@ -348,7 +348,8 @@ class SliverGridDelegateWithFixedCrossAxisCount extends SliverGridDelegate {
   }) : assert(crossAxisCount > 0),
        assert(mainAxisSpacing >= 0),
        assert(crossAxisSpacing >= 0),
-       assert(childAspectRatio > 0);
+       assert(childAspectRatio > 0),
+       assert(mainAxisExtent == null || mainAxisExtent >= 0);
 
   /// The number of children in the cross axis.
   final int crossAxisCount;
@@ -446,7 +447,8 @@ class SliverGridDelegateWithMaxCrossAxisExtent extends SliverGridDelegate {
   }) : assert(maxCrossAxisExtent > 0),
        assert(mainAxisSpacing >= 0),
        assert(crossAxisSpacing >= 0),
-       assert(childAspectRatio > 0);
+       assert(childAspectRatio > 0),
+       assert(mainAxisExtent == null || mainAxisExtent >= 0);
 
   /// The maximum extent of tiles in the cross axis.
   ///

packages/flutter/test/widgets/grid_view_test.dart

@@ -898,4 +898,48 @@ void main() {
     expect(controller.position.maxScrollExtent, 472.0);
     expect(controller.position.pixels, 472.0);
   });
+
+  testWidgets('SliverGridDelegate mainAxisExtent add assert',
+      (WidgetTester tester) async {
+    Widget buildGridView(SliverGridDelegate delegate) {
+      return Directionality(
+        textDirection: TextDirection.ltr,
+        child: GridView.builder(
+          gridDelegate: delegate,
+          itemBuilder: (BuildContext context, int index) {
+            return Container(
+              height: 50,
+              alignment: Alignment.center,
+              child: Text('$index'),
+            );
+          },
+          itemCount: 50,
+        ),
+      );
+    }
+
+    expect(
+      () => tester.pumpWidget(buildGridView(
+        SliverGridDelegateWithFixedCrossAxisCount(
+          crossAxisCount: 3,
+          mainAxisSpacing: 8,
+          crossAxisSpacing: 8,
+          mainAxisExtent: -100,
+        ),
+      )),
+      throwsA(isA<AssertionError>()),
+    );
+
+    expect(
+      () => tester.pumpWidget(buildGridView(
+        SliverGridDelegateWithMaxCrossAxisExtent(
+          maxCrossAxisExtent: 100,
+          mainAxisSpacing: 8,
+          crossAxisSpacing: 8,
+          mainAxisExtent: -100,
+        ),
+      )),
+      throwsA(isA<AssertionError>()),
+    );
+  });
 }