From 2a6c0a2a10b8d5a4f47a59d7085206d0df406278 Mon Sep 17 00:00:00 2001
From: Tim van der Lippe <tvanderlippe@gmail.com>
Date: Thu, 15 Mar 2018 11:30:06 +0100
Subject: [PATCH] Returning null in template should nullify parent template

---
 lib/mixins/element-mixin.html |  2 +-
 test/unit/inheritance.html    | 37 ++++++++++++++++++++++++++++++++++-
 2 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/lib/mixins/element-mixin.html b/lib/mixins/element-mixin.html
index 777db15243..d83946cef2 100644
--- a/lib/mixins/element-mixin.html
+++ b/lib/mixins/element-mixin.html
@@ -311,9 +311,9 @@
           } else {
             template = template.cloneNode(true);
           }
-          this.prototype._template = template;
         }
 
+        this.prototype._template = template;
       }
 
       /**
diff --git a/test/unit/inheritance.html b/test/unit/inheritance.html
index 25c8910427..497bed3b08 100644
--- a/test/unit/inheritance.html
+++ b/test/unit/inheritance.html
@@ -113,6 +113,24 @@
     </script>
   </dom-module>
 
+  <dom-module id="parent-element-template-overriding">
+    <script>
+    HTMLImports.whenReady(function() {
+      class ParentElementWithTemplate extends Polymer.Element {
+        static get template() {
+          return Polymer.html`This template should not exist`;
+        }
+      }
+      class ChildWithNoTemplate extends ParentElementWithTemplate {
+        static get template() {
+          return null;
+        }
+      }
+      customElements.define('child-with-no-template', ChildWithNoTemplate);
+    });
+    </script>
+  </dom-module>
+
   <test-fixture id="basic">
     <template>
       <base-el></base-el>
@@ -237,6 +255,23 @@
       assert.equal(child.handleCustomEvent.callCount, 1);
     });
   });
+
+  suite('child overriding a template', function() {
+    let el;
+
+    setup(function() {
+      el = document.createElement('child-with-no-template');
+      document.body.appendChild(el);
+    });
+
+    teardown(function() {
+      document.body.removeChild(el);
+    });
+
+    test('returning null nullifies the parent template', function() {
+      assert.isNotOk(el.shadowRoot);
+    });
+  });
   </script>
 </body>
-</html>
\ No newline at end of file
+</html>