fix: ExampleGetTransactionType test was failing when run as part of t…

…he unittest suite, but working properly when run individually.

This is because TransactionTypes map was being modified somewhere. Instead of investigating what changed it (non-obvious), I simply wrapped TransactionTypes map in a function to provide the const map behaviour originally intended.

transactions/transactions.go

@@ -15,23 +15,26 @@ import (
 )
 
 // TransactionTypes is a map between the ObjectTags defined above and the
-// corresponding Tx struct
-var TransactionTypes = map[uint]Transaction{
-	ObjectTagSignedTransaction:                   &SignedTx{},
-	ObjectTagSpendTransaction:                    &SpendTx{},
-	ObjectTagNameServiceClaimTransaction:         &NameClaimTx{},
-	ObjectTagNameServicePreclaimTransaction:      &NamePreclaimTx{},
-	ObjectTagNameServiceUpdateTransaction:        &NameUpdateTx{},
-	ObjectTagNameServiceRevokeTransaction:        &NameRevokeTx{},
-	ObjectTagNameServiceTransferTransaction:      &NameTransferTx{},
-	ObjectTagOracleRegisterTransaction:           &OracleRegisterTx{},
-	ObjectTagOracleQueryTransaction:              &OracleQueryTx{},
-	ObjectTagOracleResponseTransaction:           &OracleRespondTx{},
-	ObjectTagOracleExtendTransaction:             &OracleExtendTx{},
-	ObjectTagContractCreateTransaction:           &ContractCreateTx{},
-	ObjectTagContractCallTransaction:             &ContractCallTx{},
-	ObjectTagGeneralizedAccountAttachTransaction: &GAAttachTx{},
-	ObjectTagGeneralizedAccountMetaTransaction:   &GAMetaTx{},
+// corresponding Tx struct. It is wrapped by a function to guarantee you cannot
+// modify this map, because Golang does not have const maps.
+func TransactionTypes() map[uint]Transaction {
+	return map[uint]Transaction{
+		ObjectTagSignedTransaction:                   &SignedTx{},
+		ObjectTagSpendTransaction:                    &SpendTx{},
+		ObjectTagNameServiceClaimTransaction:         &NameClaimTx{},
+		ObjectTagNameServicePreclaimTransaction:      &NamePreclaimTx{},
+		ObjectTagNameServiceUpdateTransaction:        &NameUpdateTx{},
+		ObjectTagNameServiceRevokeTransaction:        &NameRevokeTx{},
+		ObjectTagNameServiceTransferTransaction:      &NameTransferTx{},
+		ObjectTagOracleRegisterTransaction:           &OracleRegisterTx{},
+		ObjectTagOracleQueryTransaction:              &OracleQueryTx{},
+		ObjectTagOracleResponseTransaction:           &OracleRespondTx{},
+		ObjectTagOracleExtendTransaction:             &OracleExtendTx{},
+		ObjectTagContractCreateTransaction:           &ContractCreateTx{},
+		ObjectTagContractCallTransaction:             &ContractCallTx{},
+		ObjectTagGeneralizedAccountAttachTransaction: &GAAttachTx{},
+		ObjectTagGeneralizedAccountMetaTransaction:   &GAMetaTx{},
+	}
 }
 
 // RLP message version used in RLP serialization
@@ -354,7 +357,7 @@ func DeserializeTx(rawRLP []byte) (Transaction, error) {
 func GetTransactionType(rawRLP []byte) (tx Transaction, err error) {
 	f := binary.DecodeRLPMessage(rawRLP)[0] // [33] interface, needs to be cast to []uint8
 	objTag := uint(f.([]uint8)[0])          // [33] cast to []uint8, get rid of the slice, cast to uint
-	return TransactionTypes[objTag], nil
+	return TransactionTypes()[objTag], nil
 }
 
 // SignedTx wraps around other Tx structs to hold the signature.