From 1f5715738ffa472bf3463b6cc6f03db2f31dde65 Mon Sep 17 00:00:00 2001
From: Ben Lesh <blesh@netflix.com>
Date: Tue, 8 Dec 2015 14:54:55 -0800
Subject: [PATCH] fix(SymbolShim): Symbol polyfill is a function

Symbol is supposed to be a function that takes a description and returns a unique symbol
such that `Symbol('foo') !== Symbol('foo')`. The polyfill therefor returns a string that has
a unique identifier concatenated to it: `@@Symbol(description):1` `@@Symbol(description):2` etc

fixes #988
---
 spec/util/SymbolShim-spec.js | 14 +++++++++++++-
 src/util/SymbolShim.ts       |  6 +++++-
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/spec/util/SymbolShim-spec.js b/spec/util/SymbolShim-spec.js
index ac251d4e5f..de77c8cab7 100644
--- a/spec/util/SymbolShim-spec.js
+++ b/spec/util/SymbolShim-spec.js
@@ -5,7 +5,19 @@ var Rx = require('../../dist/cjs/Rx');
 var polyfillSymbol = SymbolShim.polyfillSymbol;
 var ensureIterator = SymbolShim.ensureIterator;
 
-describe('SymbolShim', function () {
+describe('SymbolShim.polyfillSymbol', function () {
+  it('should polyfill Symbol to be a function that returns a primitive that is unique', function () {
+    var Symbol = polyfillSymbol({ });
+
+    expect(typeof Symbol).toBe('function');
+    var x = Symbol('test');
+    var y = Symbol('test');
+    expect(x !== y).toBe(true); // should be obvious, but this is the important part.
+
+    expect(x).toBe('@@Symbol(test):0');
+    expect(y).toBe('@@Symbol(test):1');
+  });
+
   it('should setup symbol if root does not have it', function () {
     var root = {};
 
diff --git a/src/util/SymbolShim.ts b/src/util/SymbolShim.ts
index 98e4163403..eebbf45fda 100644
--- a/src/util/SymbolShim.ts
+++ b/src/util/SymbolShim.ts
@@ -14,9 +14,13 @@ export function ensureFor(Symbol) {
   }
 }
 
+let id = 0;
+
 export function ensureSymbol(root) {
   if (!root.Symbol) {
-    root.Symbol = {};
+    root.Symbol = function symbolFuncPolyfill(description) {
+      return `@@Symbol(${description}):${id++}`;
+    };
   }
   return root.Symbol;
 }