return request body params in a consistent and usable way

lib/mock-ajax.js

@@ -78,6 +78,21 @@ function FakeXMLHttpRequest() {
       this.readyState = 2;
     },
 
+    data: function() {
+      var data = {};
+      if (typeof this.params !== 'string') return data;
+      var params = this.params.split('&');
+
+      for (var i = 0; i < params.length; ++i) {
+        var kv = params[i].split('=');
+        var key = decodeURIComponent(kv[0]);
+        data[key] = data[key] || [];
+        data[key].push(decodeURIComponent(kv[1]));
+        data[key].sort();
+      }
+      return data;
+    },
+
     getResponseHeader: function(name) {
       return this.responseHeaders[name];
     },

spec/javascripts/fake-xml-http-request-spec.js

@@ -42,4 +42,19 @@ describe("FakeXMLHttpRequest", function() {
     }
     expect(new FakeXMLHttpRequest().foo()).toEqual("foo");
   });
+
+  describe("data", function() {
+    beforeEach(function() {
+      xhr.open("POST", "http://example.com?this=that")
+      xhr.send('stooges=shemp&stooges=larry%20%26%20moe%20%26%20curly&some%3Dthing=else')
+    });
+
+    it("should return request params as a hash of arrays with values sorted alphabetically", function() {
+      var data = xhr.data();
+      expect(data['stooges'].length).toEqual(2);
+      expect(data['stooges'][0]).toEqual('larry & moe & curly');
+      expect(data['stooges'][1]).toEqual('shemp');
+      expect(data['some=thing']).toEqual(['else']);
+    });
+  });
 });