core, core/vm, cmd/disasm: unify procedures for disassembling evm code (#3530)

core/asm/asm_test.go

@@ -0,0 +1,74 @@
+// Copyright 2017 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package asm
+
+import (
+	"testing"
+
+	"encoding/hex"
+)
+
+// Tests disassembling the instructions for valid evm code
+func TestInstructionIteratorValid(t *testing.T) {
+	cnt := 0
+	script, _ := hex.DecodeString("61000000")
+
+	it := NewInstructionIterator(script)
+	for it.Next() {
+		cnt++
+	}
+
+	if err := it.Error(); err != nil {
+		t.Errorf("Expected 2, but encountered error %v instead.", err)
+	}
+	if cnt != 2 {
+		t.Errorf("Expected 2, but got %v instead.", cnt)
+	}
+}
+
+// Tests disassembling the instructions for invalid evm code
+func TestInstructionIteratorInvalid(t *testing.T) {
+	cnt := 0
+	script, _ := hex.DecodeString("6100")
+
+	it := NewInstructionIterator(script)
+	for it.Next() {
+		cnt++
+	}
+
+	if it.Error() == nil {
+		t.Errorf("Expected an error, but got %v instead.", cnt)
+	}
+}
+
+// Tests disassembling the instructions for empty evm code
+func TestInstructionIteratorEmpty(t *testing.T) {
+	cnt := 0
+	script, _ := hex.DecodeString("")
+
+	it := NewInstructionIterator(script)
+	for it.Next() {
+		cnt++
+	}
+
+	if err := it.Error(); err != nil {
+		t.Errorf("Expected 0, but encountered error %v instead.", err)
+	}
+	if cnt != 0 {
+		t.Errorf("Expected 0, but got %v instead.", cnt)
+	}
+}