[REF] component: improve render method

tests/component/__snapshots__/props_validation.test.ts.snap

@@ -1,5 +1,9 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
+exports[`default props default values are also set whenever component is updated 1`] = `"<div>1</div>"`;
+
+exports[`default props default values are also set whenever component is updated 2`] = `"<div>4</div>"`;
+
 exports[`props validation props are validated in dev mode (code snapshot) 1`] = `
 "function anonymous(context,extra
 ) {

tests/component/props_validation.test.ts

@@ -327,9 +327,17 @@ describe("default props", () => {
     class TestWidget extends Widget {
       static defaultProps = { p: 4 };
     }
+    env.qweb.addTemplates(`
+        <templates>
+            <div t-name="TestWidget"><t t-esc="props.p"/></div>
+        </templates>`);
 
     const w = new TestWidget(env, { p: 1 });
+    await w.mount(fixture);
+    expect(fixture.innerHTML).toMatchSnapshot();
     await w.__updateProps({});
+    await w.render();
     expect(w.props.p).toBe(4);
+    expect(fixture.innerHTML).toMatchSnapshot();
   });
 });