utils: Add test for Packer.UnpackByte

utils/wrappers/packing_test.go

@@ -8,7 +8,11 @@ import (
 	"testing"
 )
 
-func TestPackerByte(t *testing.T) {
+const (
+	ByteSentinal  = 0
+)
+
+func TestPackerPackByte(t *testing.T) {
 	p := Packer{MaxSize: 1}
 
 	p.PackByte(0x01)
@@ -25,6 +29,34 @@ func TestPackerByte(t *testing.T) {
 	if !bytes.Equal(p.Bytes, expected) {
 		t.Fatalf("Packer.PackByte wrote:\n%v\nExpected:\n%v", p.Bytes, expected)
 	}
+
+	p.PackByte(0x02)
+	if !p.Errored() {
+		t.Fatal("Packer.PackByte did not fail when attempt was beyond p.MaxSize")
+	}
+}
+
+func TestPackerUnpackByte(t *testing.T) {
+	var (
+		p                = Packer{Bytes: []byte{0x01}, Offset: 0}
+		actual           = p.UnpackByte()
+		expected    byte = 1
+		expectedLen      = ByteLen
+	)
+	if p.Errored() {
+		t.Fatalf("Packer.UnpackByte unexpectedly raised %s", p.Err)
+	} else if actual != expected {
+		t.Fatalf("Packer.UnpackByte returned %d, but expected %d", actual, expected)
+	} else if p.Offset != expectedLen {
+		t.Fatalf("Packer.UnpackByte left Offset %d, expected %d", p.Offset, expectedLen)
+	}
+
+	actual = p.UnpackByte()
+	if !p.Errored() {
+		t.Fatalf("Packer.UnpackByte should have set error, due to attempted out of bounds read")
+	} else if actual != ByteSentinal {
+		t.Fatalf("Packer.UnpackByte returned %d, expected sentinal value %d", actual, ByteSentinal)
+	}
 }
 
 func TestPackerShort(t *testing.T) {