fix: Double-check optimal size before adding new physical rows (#1755)

bower.json

@@ -75,8 +75,8 @@
     "iron-a11y-keys-behavior": "^v2.0.0",
     "iron-a11y-announcer": "^v2.0.0",
     "vaadin-themable-mixin": "vaadin/vaadin-themable-mixin#^1.6.1",
-    "vaadin-checkbox": "vaadin/vaadin-checkbox#^2.4.0-alpha1",
-    "vaadin-text-field": "vaadin/vaadin-text-field#^2.7.0-alpha1",
+    "vaadin-checkbox": "vaadin/vaadin-checkbox#~2.4.0-alpha3",
+    "vaadin-text-field": "vaadin/vaadin-text-field#~2.7.0-alpha4",
     "vaadin-lumo-styles": "vaadin/vaadin-lumo-styles#^1.6.0",
     "vaadin-material-styles": "vaadin/vaadin-material-styles#^1.3.2",
     "vaadin-element-mixin": "vaadin/vaadin-element-mixin#^2.4.1"

src/vaadin-grid-scroller.html

@@ -203,7 +203,7 @@
                 estimatedMissingRowCount = Math.max(0, this._effectiveSize - this._physicalCount);
               }
 
-              if (this._physicalSize && estimatedMissingRowCount > 0) {
+              if (this._physicalSize && estimatedMissingRowCount > 0 && this._optPhysicalSize !== Infinity) {
                 super._increasePoolIfNeeded(estimatedMissingRowCount);
                 // Ensure the rows are in order after increasing pool
                 this.__reorderChildNodes();

test/physical-count.html

@@ -140,7 +140,28 @@
         expect(spy).not.to.be.called;
       });
 
+      it('should not add unlimited amount of physical rows', () => {
+        const itemCount = 50;
+        grid.items = buildDataSet(itemCount);
+        flushGrid(grid);
+
+        // Repro for a really special bug:
+
+        // 1: notifyResize will trigger _increasePoolIfNeeded
+        grid.notifyResize();
+        // 2: Hide grid
+        grid.hidden = true;
+        // 3: notifyResize will trigger updateViewportBoundaries which sets _viewPortHeight to 0 because grid is not rendered
+        grid.notifyResize();
+        // 4: Restore grid to render tree
+        grid.hidden = false;
+        // 5: Finally flush the grid, and finish the async callback started at phase 1.
+        // _optPhysicalSize will be Infinity at this point so unlimited amount of rows would get added!
+        // Only thing that limits it is the grid.items count.
+        flushGrid(grid);
 
+        expect(grid.$.items.childElementCount).to.be.below(itemCount);
+      });
     });
   </script>