Throw when mixing StoreWatchMixin in without calling as a function

lib/store_watch_mixin.js

@@ -1,6 +1,6 @@
 _ = require("lodash");
 
-module.exports = function() {
+var StoreWatchMixin = function() {
   var storeNames = Array.prototype.slice.call(arguments);
   return {
     componentWillMount: function() {
@@ -26,3 +26,11 @@ module.exports = function() {
     }
   };
 };
+
+StoreWatchMixin.componentWillMount = function() {
+  throw new Error("Fluxbox.StoreWatchMixin is a function that takes one or more " +
+    "store names as parameters and returns the mixin, e.g.: " +
+    "mixins[Fluxbox.StoreWatchMixin(\"Store1\", \"Store2\")]");
+};
+
+module.exports = StoreWatchMixin;

test/unit/test_store_watch_mixin.js

@@ -95,4 +95,14 @@ describe("FluxMixin", function() {
       done();
     });
   });
+
+  it("throws when attempting to mix in the function directly", function() {
+    var Comp = React.createClass({
+      mixins: [Fluxbox.StoreWatchMixin],
+      render: function() { return React.DOM.div(); }
+    });
+    expect(function() {
+      React.renderComponentToString(Comp());
+    }).to.throw(/StoreWatchMixin.*function/);
+  });
 });