fix(decorators): don't apply instance decorators when accessing from a

prototype

.vscode/settings.json

@@ -1,3 +1,6 @@
 {
-  "typescript.tsdk": "node_modules/typescript/lib"
+  "typescript.tsdk": "node_modules/typescript/lib",
+  "cSpell.words": [
+    "applicate"
+  ]
 }

src/bind.spec.ts

@@ -60,4 +60,23 @@ describe('bind', () => {
     myClass2.fn.call(null);
     expect(context).to.equal(myClass2);
   });
+
+  it('should not bind when accessed on the prototype', () => {
+    let context;
+
+    class MyClass {
+      @Bind
+      fn() {
+        context = this;
+      }
+    }
+
+    MyClass.prototype.fn();
+
+    const myClass = new MyClass();
+
+    myClass.fn.call(null);
+
+    expect(context).to.equal(myClass);
+  });
 });

src/factory/DecoratorFactory.ts

@@ -6,7 +6,12 @@ import {
   InstanceChainContext
 } from './common';
 import { DecoratorConfig } from './DecoratorConfig';
-import { copyMetadata, bind, isMethodOrPropertyDecoratorArgs } from '../utils';
+import {
+  copyMetadata,
+  bind,
+  isMethodOrPropertyDecoratorArgs,
+  isPrototypeAccess
+} from '../utils';
 
 export type GenericDecorator = (...args: any[]) => LodashDecorator;
 
@@ -60,6 +65,7 @@ export class InternalDecoratorFactory {
         const isSetter = isFirstInstance && isFunction(set);
         const isMethod = isFirstInstance && isFunction(value);
         const isProperty = isFirstInstance && !isGetter && !isSetter && !isMethod;
+        const baseValue = isGetter ? get : isMethod ? value : undefined;
 
         chainData.properties.push(name);
         chainData.fns.push((fn: Function, instance: any, context: InstanceChainContext) => {
@@ -132,6 +138,12 @@ export class InternalDecoratorFactory {
         }
 
         descriptor.get = function() {
+          // Check for direct access on the prototype.
+          // MyClass.prototype.fn <-- This should not apply the decorator.
+          if (isPrototypeAccess(this, target)) {
+            return baseValue;
+          }
+
           applyDecorator(this);
 
           const descriptor = Object.getOwnPropertyDescriptor(this, name)!;

src/utils.ts

@@ -7,3 +7,4 @@ export * from './utils/bind';
 export * from './utils/wrapConstructor';
 export * from './utils/assignAll';
 export * from './utils/isDecoratorArgs';
+export * from './utils/isPrototypeAccess';

src/utils/isPrototypeAccess.ts

@@ -0,0 +1,5 @@
+export function isPrototypeAccess(context: object, target: object): boolean {
+  return context === target
+    || (context.constructor !== target.constructor
+      && Object.getPrototypeOf(this).constructor === target.constructor);
+}