Work on creating tests for rsync api

tools/utils/random/random.go

@@ -0,0 +1,35 @@
+// License: GPLv3 Copyright: 2023, Kovid Goyal, <kovid at kovidgoyal.net>
+
+package random
+
+import (
+	"crypto/rand"
+	"fmt"
+	"math/big"
+
+	"golang.org/x/exp/constraints"
+)
+
+var _ = fmt.Print
+
+// Return a random integer in the range [0, limit). limit must be > 0
+func Int[T constraints.Integer](limit T) T {
+	b := big.NewInt(int64(limit))
+	n, err := rand.Int(rand.Reader, b)
+	if err != nil {
+		panic(err)
+	}
+	return T(n.Uint64())
+}
+
+// Return one of items randomnly
+func Choice[T any](items ...T) T {
+	return items[Int(len(items))]
+}
+
+// Write randomn bytes into the provided slice
+func Bytes(b []byte) {
+	if _, err := rand.Read(b); err != nil {
+		panic(err)
+	}
+}