udpate test

tests/test-console/src/widget.spec.ts

@@ -286,8 +286,8 @@ describe('console/widget', () => {
         widget.promptCell.model.value.text = 'foo';
 
         let serialized = widget.serialize();
-        expect(serialized).to.have.length(2);
-        expect(serialized[1].source).to.be('foo');
+        expect(serialized).to.have.length(1);
+        expect(serialized[0].source).to.be('foo');
       });
 
     });