fix(treeGrid): Fix expansion state returning 0 instead of false in some cases.

Author: skrustev

projects/igniteui-angular/src/lib/grids/tree-grid/tree-grid-api.service.ts

@@ -76,7 +76,7 @@ export class IgxTreeGridAPIService extends GridBaseAPIService<GridType> {
         if (expanded !== undefined) {
             return expanded;
         } else {
-            return record.children && record.children.length && record.level < grid.expansionDepth;
+            return record.children && !!record.children.length && record.level < grid.expansionDepth;
         }
     }
 

projects/igniteui-angular/src/lib/grids/tree-grid/tree-grid-expanding.spec.ts

@@ -45,6 +45,15 @@ describe('IgxTreeGrid - Expanding / Collapsing #tGrid', () => {
             treeGrid = fix.componentInstance.treeGrid;
         });
 
+        it('should return boolean for expand state of row without children using getRowByKey()', () => {
+            treeGrid.primaryKey = "ID";
+            treeGrid.childDataKey = "";
+            fix.detectChanges();
+
+            const testRow = treeGrid.getRowByKey(147);
+            expect(testRow.expanded).toEqual(false);
+        });
+
         it('check row expanding and collapsing are changing rows count (UI)', () => {
             let rows = TreeGridFunctions.getAllRows(fix);
             expect(rows.length).toBe(4);