tests: enable the Constantinople fork definition

tests/init.go

@@ -53,6 +53,16 @@ var Forks = map[string]*params.ChainConfig{
 		DAOForkBlock:   big.NewInt(0),
 		ByzantiumBlock: big.NewInt(0),
 	},
+	"Constantinople": {
+		ChainID:             big.NewInt(1),
+		HomesteadBlock:      big.NewInt(0),
+		EIP150Block:         big.NewInt(0),
+		EIP155Block:         big.NewInt(0),
+		EIP158Block:         big.NewInt(0),
+		DAOForkBlock:        big.NewInt(0),
+		ByzantiumBlock:      big.NewInt(0),
+		ConstantinopleBlock: big.NewInt(0),
+	},
 	"FrontierToHomesteadAt5": {
 		ChainID:        big.NewInt(1),
 		HomesteadBlock: big.NewInt(5),