From 17caeb6b450163ebfc97173b117cf06ce2ec8ca7 Mon Sep 17 00:00:00 2001
From: Steven Sojka <steelsojka@gmail.com>
Date: Sat, 9 Jun 2018 08:24:12 -0500
Subject: [PATCH] fix(decorators): don't apply instance decorators when
 accessing from a prototype

---
 .vscode/settings.json           |  5 ++++-
 src/bind.spec.ts                | 19 +++++++++++++++++++
 src/factory/DecoratorFactory.ts | 14 +++++++++++++-
 src/utils.ts                    |  1 +
 src/utils/isPrototypeAccess.ts  |  5 +++++
 5 files changed, 42 insertions(+), 2 deletions(-)
 create mode 100644 src/utils/isPrototypeAccess.ts

diff --git a/.vscode/settings.json b/.vscode/settings.json
index 3662b37..cb3f663 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -1,3 +1,6 @@
 {
-  "typescript.tsdk": "node_modules/typescript/lib"
+  "typescript.tsdk": "node_modules/typescript/lib",
+  "cSpell.words": [
+    "applicate"
+  ]
 }
\ No newline at end of file
diff --git a/src/bind.spec.ts b/src/bind.spec.ts
index a9e6fe6..ca004b5 100644
--- a/src/bind.spec.ts
+++ b/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);
+  });
 });
diff --git a/src/factory/DecoratorFactory.ts b/src/factory/DecoratorFactory.ts
index 20791cb..3bacb5b 100644
--- a/src/factory/DecoratorFactory.ts
+++ b/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)!;
diff --git a/src/utils.ts b/src/utils.ts
index e82baba..39563d6 100644
--- a/src/utils.ts
+++ b/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';
diff --git a/src/utils/isPrototypeAccess.ts b/src/utils/isPrototypeAccess.ts
new file mode 100644
index 0000000..9c61281
--- /dev/null
+++ b/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);
+}