Add tests to check for data race in broker

We had some data races in the broker that occur when proxies and clients
modify the heap/snowflake map at the same time. This test has a client
and proxy access the broker simultaneously to check for data races.

broker/snowflake-broker_test.go

@@ -191,12 +191,61 @@ func TestBroker(t *testing.T) {
 			})
 
 		})
+
 	})
 
 	Convey("End-To-End", t, func() {
+		ctx := NewBrokerContext(NullLogger())
+
+		Convey("Check for client/proxy data race", func() {
+			proxy_done := make(chan bool)
+			client_done := make(chan bool)
+
+			go ctx.Broker()
+
+			// Make proxy poll
+			wp := httptest.NewRecorder()
+			datap := bytes.NewReader([]byte(`{"Sid":"ymbcCMto7KHNGYlp","Version":"1.0"}`))
+			rp, err := http.NewRequest("POST", "snowflake.broker/proxy", datap)
+			So(err, ShouldBeNil)
+
+			go func(ctx *BrokerContext) {
+				proxyPolls(ctx, wp, rp)
+				proxy_done <- true
+			}(ctx)
+
+			// Client offer
+			wc := httptest.NewRecorder()
+			datac := bytes.NewReader([]byte("test"))
+			rc, err := http.NewRequest("POST", "snowflake.broker/client", datac)
+			So(err, ShouldBeNil)
+
+			go func() {
+				clientOffers(ctx, wc, rc)
+				client_done <- true
+			}()
+
+			<-proxy_done
+			So(wp.Code, ShouldEqual, http.StatusOK)
+
+			// Proxy answers
+			wp = httptest.NewRecorder()
+			datap = bytes.NewReader([]byte(`{"Version":"1.0","Sid":"ymbcCMto7KHNGYlp","Answer":"test"}`))
+			rp, err = http.NewRequest("POST", "snowflake.broker/answer", datap)
+			So(err, ShouldBeNil)
+			go func(ctx *BrokerContext) {
+				proxyAnswers(ctx, wp, rp)
+				proxy_done <- true
+			}(ctx)
+
+			<-proxy_done
+			<-client_done
+
+		})
+
+		Convey("Ensure correct snowflake brokering", func() {
 			done := make(chan bool)
 			polled := make(chan bool)
-		ctx := NewBrokerContext(NullLogger())
 
 			// Proxy polls with its ID first...
 			dataP := bytes.NewReader([]byte(`{"Sid":"ymbcCMto7KHNGYlp","Version":"1.0"}`))
@@ -244,6 +293,7 @@ func TestBroker(t *testing.T) {
 			So(wC.Code, ShouldEqual, http.StatusOK)
 			So(wC.Body.String(), ShouldEqual, "test")
 		})
+	})
 }
 
 func TestSnowflakeHeap(t *testing.T) {