feat(applying): check non-empty set of inputs and outputs (#312)

pallas-applying/src/byron.rs

@@ -1,14 +1,30 @@
 //! Utilities required for Byron-era transaction validation.
 
-use crate::types::{ByronProtParams, UTxOs, ValidationResult};
+use crate::types::{ByronProtParams, UTxOs, ValidationError, ValidationResult};
 
-use pallas_primitives::byron::MintedTxPayload;
+use pallas_primitives::byron::{MintedTxPayload, Tx};
 
-// TODO: implement each of the validation rules.
+// TODO: implement missing validation rules.
 pub fn validate_byron_tx(
-    _mtxp: &MintedTxPayload,
+    mtxp: &MintedTxPayload,
     _utxos: &UTxOs,
     _prot_pps: &ByronProtParams,
 ) -> ValidationResult {
+    let tx: &Tx = &mtxp.transaction;
+    check_ins_not_empty(tx)?;
+    check_outs_not_empty(tx)
+}
+
+fn check_ins_not_empty(tx: &Tx) -> ValidationResult {
+    if tx.inputs.clone().to_vec().is_empty() {
+        return Err(ValidationError::TxInsEmpty);
+    }
+    Ok(())
+}
+
+fn check_outs_not_empty(tx: &Tx) -> ValidationResult {
+    if tx.outputs.clone().to_vec().is_empty() {
+        return Err(ValidationError::TxOutsEmpty);
+    }
     Ok(())
 }

pallas-applying/src/types.rs

@@ -21,7 +21,8 @@ pub enum MultiEraProtParams<'b> {
 #[derive(Debug)]
 #[non_exhaustive]
 pub enum ValidationError {
-    ValidationError,
+    TxInsEmpty,
+    TxOutsEmpty,
 }
 
 pub type ValidationResult = Result<(), ValidationError>;