vm: support Map in ARRAYSIZE

Also make logic the same as in reference implementation
and add tests.

pkg/vm/vm.go

@@ -807,10 +807,10 @@ func (v *VM) execute(ctx *Context, op Instruction) {
 		switch t := elem.value.Value().(type) {
 		case []StackItem:
 			v.estack.PushVal(len(t))
-		case []uint8:
+		case map[interface{}]StackItem:
 			v.estack.PushVal(len(t))
 		default:
-			panic("ARRAYSIZE: item not of type []StackItem")
+			v.estack.PushVal(len(elem.Bytes()))
 		}
 
 	case SIZE:

pkg/vm/vm_test.go

@@ -727,6 +727,34 @@ func TestSIZEBool(t *testing.T) {
 	assert.Equal(t, makeStackItem(1), vm.estack.Pop().value)
 }
 
+func TestARRAYSIZEArray(t *testing.T) {
+	prog := makeProgram(ARRAYSIZE)
+	vm := load(prog)
+	vm.estack.PushVal([]StackItem{
+		makeStackItem(1),
+		makeStackItem([]byte{}),
+	})
+	vm.Run()
+	assert.Equal(t, false, vm.HasFailed())
+	assert.Equal(t, 1, vm.estack.Len())
+	assert.Equal(t, makeStackItem(2), vm.estack.Pop().value)
+}
+
+func TestARRAYSIZEMap(t *testing.T) {
+	prog := makeProgram(ARRAYSIZE)
+	vm := load(prog)
+
+	m := NewMapItem()
+	m.Add(makeStackItem(5), makeStackItem(6))
+	m.Add(makeStackItem([]byte{0, 1}), makeStackItem(6))
+	vm.estack.Push(&Element{value: m})
+
+	vm.Run()
+	assert.Equal(t, false, vm.HasFailed())
+	assert.Equal(t, 1, vm.estack.Len())
+	assert.Equal(t, makeStackItem(2), vm.estack.Pop().value)
+}
+
 func TestKEYSMap(t *testing.T) {
 	prog := makeProgram(KEYS)
 	vm := load(prog)