Fixed typo in chain_test.go

chain_test.go

diff --git a/chain_test.go b/chain_test.go
index 22ffb9b..25a9b1b 100644
--- a/chain_test.go
+++ b/chain_test.go
@@ -131,7 +131,7 @@
 		t.Error("chain2 should contain 2 constructors")
 	}
 	if len(newChain.constructors) != 4 {
-		t.Error("newChainshould contain 4 constructors")
+		t.Error("newChain should contain 4 constructors")
 	}
 
 	chained := newChain.Then(testApp)