Harden Snowboard (#687)

Backport from 1.2 branch.

- The Snowboard and PluginLoader objects are now frozen and cannot be modified.
- Added a Proxy in front of Snowboard to handle plugin loading
- Plugin "Snowboard" instances are blocked from running certain methods
- Update tests to check hardening

Author: bennothommo

modules/system/.eslintrc.json

@@ -32,5 +32,9 @@
             "math": "always"
         }],
         "vue/multi-word-component-names": ["off"]
-    }
+    },
+    "ignorePatterns": [
+        "tests/js",
+        "**/build/*.js"
+    ]
 }

modules/system/assets/js/build/manifest.js

@@ -0,0 +1,43 @@
+/**
+ * Internal proxy for Snowboard.
+ *
+ * This handler wraps the Snowboard instance that is passed to the constructor of plugin instances.
+ * It prevents access to the following methods:
+ *  - `attachAbstracts`: No need to attach abstracts again.
+ *  - `loadUtilties`: No need to load utilities again.
+ *  - `initialise`: Snowboard is already initialised.
+ *  - `initialiseSingletons`: Singletons are already initialised.
+ */
+export default {
+    get(target, prop, receiver) {
+        if (typeof prop === 'string') {
+            const propLower = prop.toLowerCase();
+
+            if (['attachAbstracts', 'loadUtilities', 'initialise', 'initialiseSingletons'].includes(prop)) {
+                throw new Error(`You cannot use the "${prop}" Snowboard method within a plugin.`);
+            }
+
+            if (target.hasPlugin(propLower)) {
+                return (...params) => Reflect.get(target, 'plugins')[propLower].getInstance(...params);
+            }
+        }
+
+        return Reflect.get(target, prop, receiver);
+    },
+
+    has(target, prop) {
+        if (typeof prop === 'string') {
+            const propLower = prop.toLowerCase();
+
+            if (['attachAbstracts', 'loadUtilities', 'initialise', 'initialiseSingletons'].includes(prop)) {
+                return false;
+            }
+
+            if (target.hasPlugin(propLower)) {
+                return true;
+            }
+        }
+
+        return Reflect.has(target, prop);
+    },
+};