change fdb string representation to common format

bindings/go/src/fdb/fdb.go

@@ -34,6 +34,7 @@ import (
 	"fmt"
 	"log"
 	"runtime"
+	"strings"
 	"sync"
 	"unsafe"
 )
@@ -384,6 +385,23 @@ func (k Key) FDBKey() Key {
 	return k
 }
 
+// String describes the key as a hexadecimal encoded string.
+func (k Key) String() string {
+	var sb strings.Builder
+	for _, b := range k {
+		if b >= 32 && b < 127 && b != '\\' {
+			sb.WriteByte(b)
+			continue
+		}
+		if b == '\\' {
+			sb.WriteString("\\\\")
+			continue
+		}
+		sb.WriteString(fmt.Sprintf("\\x%x", b))
+	}
+	return sb.String()
+}
+
 func panicToError(e *error) {
 	if r := recover(); r != nil {
 		fe, ok := r.(Error)

bindings/go/src/fdb/fdb_test.go

@@ -24,8 +24,9 @@ package fdb_test
 
 import (
 	"fmt"
-	"github.com/apple/foundationdb/bindings/go/src/fdb"
 	"testing"
+
+	"github.com/apple/foundationdb/bindings/go/src/fdb"
 )
 
 func ExampleOpenDefault() {
@@ -261,3 +262,19 @@ func ExampleRangeIterator() {
 	// banana is bar
 	// cherry is baz
 }
+
+func TestKeyToString(t *testing.T) {
+	cases := []struct {
+		key    fdb.Key
+		expect string
+	}{
+		{fdb.Key("plain-text"), "plain-text"},
+		{fdb.Key("\xbdascii☻☺"), "\\xbdascii\\xe2\\x98\\xbb\\xe2\\x98\\xba"},
+	}
+
+	for i, c := range cases {
+		if s := c.key.String(); s != c.expect {
+			t.Errorf("got '%v', want '%v' at case %v", s, c.expect, i)
+		}
+	}
+}