Move ChannelReceivesSomething to tests package.

ChannelReceivesSomething (formerly WaitForChannel) originally was
located in the helpers package.
This move was done to remove a cyclic dependency with the nomand package.

tests/util.go

@@ -0,0 +1,14 @@
+package tests
+
+import "time"
+
+// ChannelReceivesSomething waits timeout seconds for something to be received from channel ch.
+// If something is received, it returns true. If the timeout expires without receiving anything, it return false.
+func ChannelReceivesSomething(ch chan bool, timeout time.Duration) bool {
+	select {
+	case <-ch:
+		return true
+	case <-time.After(timeout):
+		return false
+	}
+}