Protect context properties and methods from overwriting

addon-test-support/@ember/test-helpers/setup-context.js

@@ -167,31 +167,46 @@ export default function(context, options = {}) {
       return buildOwner(getApplication(), getResolver());
     })
     .then(owner => {
-      context.owner = owner;
+      Object.defineProperty(context, 'owner', {
+        value: owner,
+        writable: false,
+      });
 
-      context.set = function(key, value) {
-        let ret = run(function() {
-          return set(context, key, value);
-        });
+      Object.defineProperty(context, 'set', {
+        value(key, value) {
+          let ret = run(function() {
+            return set(context, key, value);
+          });
 
-        return ret;
-      };
+          return ret;
+        },
+        writable: false,
+      });
 
-      context.setProperties = function(hash) {
-        let ret = run(function() {
-          return setProperties(context, hash);
-        });
+      Object.defineProperty(context, 'setProperties', {
+        value(hash) {
+          let ret = run(function() {
+            return setProperties(context, hash);
+          });
 
-        return ret;
-      };
+          return ret;
+        },
+        writable: false,
+      });
 
-      context.get = function(key) {
-        return get(context, key);
-      };
+      Object.defineProperty(context, 'get', {
+        value(key) {
+          return get(context, key);
+        },
+        writable: false,
+      });
 
-      context.getProperties = function(...args) {
-        return getProperties(context, args);
-      };
+      Object.defineProperty(context, 'getProperties', {
+        value(...args) {
+          return getProperties(context, args);
+        },
+        writable: false,
+      });
 
       let resume;
       context.resumeTest = function resumeTest() {

addon-test-support/@ember/test-helpers/setup-rendering-context.js

@@ -154,11 +154,14 @@ export default function setupRenderingContext(context) {
       // these methods being placed on the context itself will be deprecated in
       // a future version (no giant rush) to remove some confusion about which
       // is the "right" way to things...
-      context.render = render;
-      context.clearRender = clearRender;
+      Object.defineProperty(context, 'render', { value: render, writable: false });
+      Object.defineProperty(context, 'clearRender', {
+        value: clearRender,
+        writable: false,
+      });
 
       if (global.jQuery) {
-        context.$ = jQuerySelector;
+        Object.defineProperty(context, '$', { value: jQuerySelector, writable: false });
       }
 
       // When the host app uses `setApplication` (instead of `setResolver`) the event dispatcher has
@@ -190,18 +193,21 @@ export default function setupRenderingContext(context) {
       });
     })
     .then(() => {
-      // ensure the element is based on the wrapping toplevel view
-      // Ember still wraps the main application template with a
-      // normal tagged view
-      //
-      // In older Ember versions (2.4) the element itself is not stable,
-      // and therefore we cannot update the `this.element` until after the
-      // rendering is completed
-      if (EmberENV._APPLICATION_TEMPLATE_WRAPPER !== false) {
-        context.element = getRootElement().querySelector('.ember-view');
-      } else {
-        context.element = getRootElement();
-      }
+      Object.defineProperty(context, 'element', {
+        // ensure the element is based on the wrapping toplevel view
+        // Ember still wraps the main application template with a
+        // normal tagged view
+        //
+        // In older Ember versions (2.4) the element itself is not stable,
+        // and therefore we cannot update the `this.element` until after the
+        // rendering is completed
+        value:
+          EmberENV._APPLICATION_TEMPLATE_WRAPPER !== false
+            ? getRootElement().querySelector('.ember-view')
+            : getRootElement(),
+
+        writable: false,
+      });
 
       return context;
     });

tests/unit/setup-context-test.js

@@ -43,6 +43,14 @@ module('setupContext', function(hooks) {
     setResolver(resolver);
   });
 
+  function overwriteTest(context, key) {
+    test(`throws an error when trying to overwrite this.${key}`, function(assert) {
+      assert.throws(() => {
+        context[key] = null;
+      }, TypeError);
+    });
+  }
+
   function setupContextTests() {
     module('without options', function(hooks) {
       hooks.beforeEach(function() {
@@ -60,6 +68,8 @@ module('setupContext', function(hooks) {
         }
       });
 
+      overwriteTest(context, 'owner');
+
       test('it uses the default resolver if no override specified', function(assert) {
         let { owner } = context;
         let instance = owner.lookup('service:foo');
@@ -104,6 +114,11 @@ module('setupContext', function(hooks) {
         );
       });
 
+      overwriteTest(context, 'set');
+      overwriteTest(context, 'setProperties');
+      overwriteTest(context, 'get');
+      overwriteTest(context, 'getProperties');
+
       test('it calls setContext with the provided context', function(assert) {
         assert.equal(getContext(), context);
       });

tests/unit/setup-rendering-context-test.js

@@ -30,6 +30,14 @@ module('setupRenderingContext', function(hooks) {
     setResolver(resolver);
   });
 
+  function overwriteTest(key) {
+    test(`throws an error when trying to overwrite this.${key}`, function(assert) {
+      assert.throws(() => {
+        this[key] = null;
+      }, TypeError);
+    });
+  }
+
   function setupRenderingContextTests(hooks) {
     hooks.beforeEach(async function() {
       setResolverRegistry({
@@ -72,6 +80,8 @@ module('setupRenderingContext', function(hooks) {
       });
     }
 
+    overwriteTest('element');
+
     test('render can be used multiple times', async function(assert) {
       await this.render(hbs`<p>Hello!</p>`);
       assert.equal(this.element.textContent, 'Hello!');
@@ -108,6 +118,9 @@ module('setupRenderingContext', function(hooks) {
       assert.strictEqual(this.element, originalElement, 'this.element is stable');
     });
 
+    overwriteTest('render');
+    overwriteTest('clearRender');
+
     (hasjQuery() ? test : skip)('this.$ is exposed when jQuery is present', async function(assert) {
       await this.render(hbs`<p>Hello!</p>`);