common: support checking custom types

Author: stephenplusplus

packages/common/src/util.js

@@ -599,3 +599,29 @@ function createLimiter(makeRequestFn, options) {
 }
 
 util.createLimiter = createLimiter;
+
+function isCustomType(unknown, module) {
+  function getConstructorName(obj) {
+    return obj.constructor && obj.constructor.name.toLowerCase();
+  }
+
+  var moduleNameParts = module.split('/');
+
+  var parentModuleName = moduleNameParts[0] && moduleNameParts[0].toLowerCase();
+  var subModuleName = moduleNameParts[1] && moduleNameParts[1].toLowerCase();
+
+  if (subModuleName && getConstructorName(unknown) !== subModuleName) {
+    return false;
+  }
+
+  var walkingModule = unknown;
+  while (walkingModule.parent && (walkingModule = walkingModule.parent)) {
+    if (getConstructorName(walkingModule) === parentModuleName) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+util.isCustomType = isCustomType;

packages/common/test/util.js

@@ -1370,4 +1370,30 @@ describe('common/util', function() {
       });
     });
   });
+
+  describe('isCustomType', function() {
+    function PubSub() {}
+
+    function MiddleLayer() {
+      this.parent = new PubSub();
+    }
+
+    function Subscription() {
+      this.parent = new MiddleLayer();
+    }
+
+    var subscription = new Subscription();
+
+    it('should match a custom type by constructor names', function() {
+      assert(util.isCustomType(subscription, 'pubsub'));
+      assert(util.isCustomType(subscription, 'pubsub/subscription'));
+
+      assert(util.isCustomType(subscription, 'middlelayer'));
+      assert(util.isCustomType(subscription, 'middlelayer/subscription'));
+    });
+
+    it('should support any casing', function() {
+      assert(util.isCustomType(subscription, 'PubSub/Subscription'));
+    });
+  });
 });