Add unsafe byte to string and back conversion

go.mod

@@ -1,6 +1,6 @@
 module github.com/mailgun/holster/v4
 
-go 1.19
+go 1.20
 
 require (
 	github.com/Shopify/toxiproxy v2.1.4+incompatible

unsafe/unsafe.go

@@ -0,0 +1,20 @@
+package unsafe
+
+import (
+	"unsafe"
+)
+
+// BytesToString converts a byte slice to a string without allocation. The
+// returned string reuses the slice byte array. Since Go strings are immutable,
+// the bytes passed to BytesToString must not be modified afterwards.
+func BytesToString(b []byte) string {
+	return unsafe.String(unsafe.SliceData(b), len(b))
+}
+
+// StringToBytes converts a string to a byte slice without allocation. The
+// returned byte slice reuses the underlying string byte array. Since Go
+// strings are immutable, the bytes returned by StringToBytes must not be
+// modified.
+func StringToBytes(s string) []byte {
+	return unsafe.Slice(unsafe.StringData(s), len(s))
+}

unsafe/unsafe_test.go

@@ -0,0 +1,15 @@
+package unsafe
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestBytesToString(t *testing.T) {
+	assert.Equal(t, "hello", BytesToString([]byte("hello")))
+}
+
+func TestStringToBytes(t *testing.T) {
+	assert.Equal(t, []byte("hello"), StringToBytes("hello"))
+}