More updates based on code review.

lib/legacy/class.js

@@ -345,10 +345,5 @@ export const Class = function(info) {
     LegacyElementMixin(HTMLElement));
   // decorate klass with registration info
   klass.is = info.is;
-  // if user provided template on info, make sure the static _template
+  return klass;
-  // is set so the static template getter uses it
-  if (info._template !== undefined) {
-    klass._template = info._template;
-  }
-return klass;
 };

lib/mixins/element-mixin.js

@@ -403,14 +403,14 @@ export const ElementMixin = dedupingMixin(base => {
     static get template() {
       if (!this.hasOwnProperty(JSCompiler_renameProperty('_template', this))) {
         this._template =
+          // Take any template set on the prototype, including null (for legacy
+          // support, setting in registered callback, etc.)
+          this.prototype._template !== undefined ? this.prototype._template :
           // Look in dom-module associated with this element's is
           getTemplateFromDomModule(/** @type {PolymerElementConstructor}*/ (this).is) ||
           // Next look for superclass template (call the super impl this
           // way so that `this` points to the superclass)
-          Object.getPrototypeOf(/** @type {PolymerElementConstructor}*/ (this).prototype).constructor.template ||
+          Object.getPrototypeOf(/** @type {PolymerElementConstructor}*/ (this).prototype).constructor.template;
-          // Finally, fall back to any _template set on prototype, e.g.
-          // via registered callback
-          this.prototype._template;
       }
       return this._template;
   }

lib/utils/templatize.js

@@ -499,7 +499,7 @@ export function templatize(template, owner, options) {
   // Under strictTemplatePolicy, the templatized element must be owned
   // by a (trusted) Polymer element, indicated by existence of _methodHost;
   // e.g. for dom-if & dom-repeat in main document, _methodHost is null
-  if (strictTemplatePolicy && !owner._methodHost) {
+  if (strictTemplatePolicy && !findMethodHost(template)) {
     throw new Error('strictTemplatePolicy: template owner not trusted');
   }
   options = /** @type {!TemplatizeOptions} */(options || {});

test/unit/behaviors.html

@@ -23,8 +23,14 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
     </template>
   </dom-module>
 
+  <dom-module id="template-from-behavior">
+    <template>
+      <div id="from-base">should not be used</div>
+    </template>
+  </dom-module>
+
   <script type="module">
-import { Polymer } from '../../polymer-legacy.js';
+import { Polymer, html } from '../../polymer-legacy.js';
 window.BehaviorA = {
   properties: {
 
@@ -284,6 +290,50 @@ Polymer({
 
   is: 'behavior-registered'
 });
+
+window.templateBehavior1 = {
+  _template: html`<div id="from-behavior1"></div>`
+};
+
+window.templateBehavior2 = {
+  _template: html`<div id="from-behavior2"></div>`
+};
+
+window.templateBehaviorFromRegister = {
+  registered: function() {
+    this._template = html`<div id="behavior-from-register"></div>`;
+  }
+};
+
+Polymer({
+  is: 'template-from-registered',
+  registered: function() {
+    this._template = html`<div id="from-registered"></div>`;
+  }
+});
+
+Polymer({
+  is: 'template-from-behavior',
+  behaviors: [
+    window.templateBehavior1
+  ]
+});
+
+Polymer({
+  is: 'template-from-behavior-overridden',
+  behaviors: [
+    window.templateBehavior1,
+    window.templateBehavior2
+  ]
+});
+
+Polymer({
+  is: 'template-from-behavior-registered',
+  behaviors: [
+    window.templateBehavior1,
+    window.templateBehaviorFromRegister
+  ]
+});
 </script>
 
   <test-fixture id="single">
@@ -309,6 +359,31 @@ Polymer({
       <behavior-registered></behavior-registered>
     </template>
   </test-fixture>
+  
+  <test-fixture id="from-registered">
+    <template>
+      <template-from-registered></template-from-registered>
+    </template>
+  </test-fixture>
+
+  <test-fixture id="from-behavior">
+    <template>
+      <template-from-behavior></template-from-behavior>
+    </template>
+  </test-fixture>
+
+  <test-fixture id="from-behavior-overridden">
+    <template>
+      <template-from-behavior-overridden></template-from-behavior-overridden>
+    </template>
+  </test-fixture>
+
+  <test-fixture id="from-behavior-registered">
+    <template>
+      <template-from-behavior-registered></template-from-behavior-registered>
+    </template>
+  </test-fixture>
+
 <script type="module">
 import { Polymer } from '../../polymer-legacy.js';
 
@@ -505,6 +580,34 @@ suite('nested-behaviors element', function() {
   });
 
 });
+
+suite('templates from behaviors', function() {
+
+  test('template from registered callback', function() {
+    var el = fixture('from-registered');
+    assert.ok(el.shadowRoot.querySelector('#from-registered'));
+  });
+
+  test('template from behavior', function() {
+    var el = fixture('from-behavior');
+    assert.notOk(el.shadowRoot.querySelector('#from-base'));
+    assert.ok(el.shadowRoot.querySelector('#from-behavior1'));
+  });
+
+  test('template from overriding behavior', function() {
+    var el = fixture('from-behavior-overridden');
+    assert.notOk(el.shadowRoot.querySelector('#from-behavior1'));
+    assert.ok(el.shadowRoot.querySelector('#from-behavior2'));
+  });
+
+  test('template from behavior registered callback', function() {
+    var el = fixture('from-behavior-registered');
+    assert.notOk(el.shadowRoot.querySelector('#from-behavior1'));
+    assert.ok(el.shadowRoot.querySelector('#behavior-from-register'));
+  });
+
+});
+
 </script>
 
 </body>

test/unit/strict-template-policy.html

@@ -78,7 +78,7 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
   <div id="target"></div>
     
   <script type="module">
-    import {PolymerElement} from '../../polymer-element.js';
+    import {PolymerElement, html} from '../../polymer-element.js';
     import {Polymer} from '../../polymer-legacy.js';
     import {flush} from '../../lib/utils/flush.js';
     import {setAllowTemplateFromDomModule} from '../../lib/utils/settings.js';
@@ -94,10 +94,10 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
       // the call stack to the dom methods that provoked them, so this
       // wraps Chai's assert.throws to re-throw uncaught errors
       function assertThrows(fn, re) {
-        let uncaughtError = null;
         // Catch uncaught errors; note when running in iframe sometimes
         // Safari errors are thrown on the top window, sometimes not, so
         // catch in both places
+        let uncaughtError = null;
         window.uncaughtErrorFilter = window.top.uncaughtErrorFilter = function(err) {
           if (!uncaughtError) {
             uncaughtError = err;
@@ -179,11 +179,27 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
             '  <template>' +
             '    <div id="injected"></div>'+
             '  </template>`' +
-            '</dom-module>' +
+            '</dom-module>';
-            '<trusted-element></trusted-element>';
         }, /trusted-element re-registered/);
-        const el = document.querySelector('trusted-element');
+        const el = document.createElement('trusted-element');
-        assert.notOk(el && el.shadowRoot && el.shadowRoot.querySelector('#injected'));
+        document.getElementById('target').appendChild(el);
+        assert.notOk(el.shadowRoot);
+        assert.notOk(document.getElementById('injected'));
+      });
+      
+      test('dom-module after registration, again', function() {
+        assertThrows(function() {
+          document.getElementById('target').innerHTML =
+            '<dom-module id="trusted-element">' +
+            '  <template>' +
+            '    <div id="injected"></div>'+
+            '  </template>`' +
+            '</dom-module>';
+        }, /trusted-element re-registered/);
+        const el = document.createElement('trusted-element');
+        document.getElementById('target').appendChild(el);
+        assert.notOk(el.shadowRoot);
+        assert.notOk(document.getElementById('injected'));
       });
       
       test('dom-module before registration', function() {
@@ -201,6 +217,7 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
         let el = document.createElement('has-no-template');
         document.getElementById('target').appendChild(el);
         assert.notOk(el.shadowRoot);
+        assert.notOk(document.getElementById('injected'));
       });
 
       test('dom-module after registration (legacy)', function() {
@@ -210,13 +227,29 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
             '  <template>' +
             '    <div id="injected"></div>'+
             '  </template>`' +
-            '</dom-module>' +
+            '</dom-module>';
-            '<trusted-element-legacy></trusted-element-legacy>';
         }, /trusted-element-legacy re-registered/);
-        const el = document.querySelector('trusted-element-legacy');
+        const el = document.createElement('trusted-element-legacy');
-        assert.notOk(el && el.shadowRoot && el.shadowRoot.querySelector('#injected'));
+        document.getElementById('target').appendChild(el);
+        assert.notOk(el.shadowRoot);
+        assert.notOk(document.getElementById('injected'));
       });
       
+      test('dom-module after registration, again (legacy)', function() {
+        assertThrows(function() {
+          document.getElementById('target').innerHTML =
+            '<dom-module id="trusted-element-legacy">' +
+            '  <template>' +
+            '    <div id="injected"></div>'+
+            '  </template>`' +
+            '</dom-module>';
+        }, /trusted-element-legacy re-registered/);
+        const el = document.createElement('trusted-element-legacy');
+        document.getElementById('target').appendChild(el);
+        assert.notOk(el.shadowRoot);
+        assert.notOk(document.getElementById('injected'));
+      });
+            
       test('dom-module before registration (legacy)', function() {
         document.getElementById('target').innerHTML =
           '<dom-module id="has-no-template-legacy">' +
@@ -230,7 +263,8 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
         });
         let el = document.createElement('has-no-template-legacy');
         document.getElementById('target').appendChild(el);
-        assert.notOk(document.querySelector('has-no-template-legacy').shadowRoot);
+        assert.notOk(el.shadowRoot);
+        assert.notOk(document.getElementById('injected'));
       });
 
       test('element without explicit template throws', function() {
@@ -253,8 +287,68 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
           document.getElementById('target').appendChild(el);
         }, /expecting dom-module or null template/);
       });
-      
+
+      test('template helpers in trusted templates work', function() {
+        
+        class TrustedTemplates extends PolymerElement {
+          static get template() { return html`
+            <dom-repeat items="[0]">
+              <template>
+                <div id="dom-repeat-ok"></div>
+                <dom-if if>
+                  <template><div id="nested-dom-if-ok"></div></template>
+                </dom-if>
+              </template>
+            </dom-repeat>
+            <dom-if if>
+              <template>
+                <div id="dom-if-ok"></div>
+                <dom-repeat items="[0]">
+                  <template>
+                    <div id="nested-dom-repeat-ok"></div>
+                  </template>
+                </dom-repeat>
+              </template>
+            </dom-if>`; 
+          }
+        }
+        customElements.define('trusted-templates', TrustedTemplates);
+    
+        var el = document.createElement('trusted-templates');
+        document.getElementById('target').appendChild(el);
+        flush();
+        assert.ok(el.shadowRoot.querySelector('#dom-repeat-ok'));
+        assert.ok(el.shadowRoot.querySelector('#dom-if-ok'));
+        assert.ok(el.shadowRoot.querySelector('#nested-dom-repeat-ok'));
+        assert.ok(el.shadowRoot.querySelector('#nested-dom-if-ok'));
+      });
+
+      test('template helpers in trusted templates work (legacy)', function() {
+
+        Polymer({
+          is: 'trusted-templates-legacy',
+          _template: html`
+            <template is="dom-repeat" items="[0]">
+              <div id="dom-repeat-ok"></div>
+              <template is="dom-if" if><div id="nested-dom-if-ok"></div></template>
+            </template>
+            <template is="dom-if" if>
+              <div id="dom-if-ok"></div>
+              <template is="dom-repeat" items="[0]"><div id="nested-dom-repeat-ok"></div></template>
+            </template>`
+        });
+
+        var el = document.createElement('trusted-templates-legacy');
+        document.getElementById('target').appendChild(el);
+        flush();
+        assert.ok(el.shadowRoot.querySelector('#dom-repeat-ok'));
+        assert.ok(el.shadowRoot.querySelector('#dom-if-ok'));
+        assert.ok(el.shadowRoot.querySelector('#nested-dom-repeat-ok'));
+        assert.ok(el.shadowRoot.querySelector('#nested-dom-if-ok'));
+      });
+
     });
+
   </script>
     
 </body>