fix: reject duplicate remaining allotments

Author: flemzord

internal/interpreter/interpreter.go

@@ -1029,9 +1029,13 @@ func (s *programState) makeAllotment(monetary *big.Int, items []parser.Allotment
 			allotments = append(allotments, rat)
 
 		case *parser.RemainingAllotment:
+			if remainingAllotmentIndex != -1 {
+				return nil, InvalidRemainingAllotment{
+					Range: allotment.Range,
+				}
+			}
 			remainingAllotmentIndex = i
 			allotments = append(allotments, new(big.Rat))
-			// TODO check there are not duplicate remaining clause
 		}
 	}
 

internal/interpreter/interpreter_error.go

@@ -153,6 +153,14 @@ func (e InvalidAllotmentInSendAll) Error() string {
 	return "cannot take all balance of an allotment source"
 }
 
+type InvalidRemainingAllotment struct {
+	parser.Range
+}
+
+func (e InvalidRemainingAllotment) Error() string {
+	return "Only one 'remaining' clause is allowed in an allotment expression"
+}
+
 type DivideByZero struct {
 	parser.Range
 	Numerator *big.Int

numscript_test.go

@@ -58,6 +58,27 @@ func TestGetVarsNovars(t *testing.T) {
 	)
 }
 
+func TestRunRejectsDuplicateRemainingAllotments(t *testing.T) {
+	parseResult := numscript.Parse(`send [COIN 100] (
+	source = {
+		remaining from @a
+		remaining from @b
+	}
+	destination = @dest
+)
+`)
+	require.Empty(t, parseResult.GetParsingErrors())
+
+	_, err := parseResult.Run(context.Background(), numscript.VariablesMap{}, interpreter.StaticStore{
+		Balances: interpreter.Balances{
+			"a": {"COIN": big.NewInt(100)},
+			"b": {"COIN": big.NewInt(100)},
+		},
+	})
+	require.Error(t, err)
+	require.Contains(t, err.Error(), "remaining")
+}
+
 func TestDoNotGetWorldBalance(t *testing.T) {
 	parseResult := numscript.Parse(`send [COIN 100] (
 	source = @world