moving random.go from utils

Closes #10962
Signed-off-by: Srini Brahmaroutu <srbrahma@us.ibm.com>

common/randomid.go

@@ -36,3 +36,12 @@ func GenerateRandomID() string {
 		return value
 	}
 }
+
+func RandomString() string {
+	id := make([]byte, 32)
+
+	if _, err := io.ReadFull(rand.Reader, id); err != nil {
+		panic(err) // This shouldn't happen
+	}
+	return hex.EncodeToString(id)
+}

common/randomid_test.go

@@ -0,0 +1,59 @@
+package common
+
+import (
+	"testing"
+)
+
+func TestShortenId(t *testing.T) {
+	id := GenerateRandomID()
+	truncID := TruncateID(id)
+	if len(truncID) != 12 {
+		t.Fatalf("Id returned is incorrect: truncate on %s returned %s", id, truncID)
+	}
+}
+
+func TestShortenIdEmpty(t *testing.T) {
+	id := ""
+	truncID := TruncateID(id)
+	if len(truncID) > len(id) {
+		t.Fatalf("Id returned is incorrect: truncate on %s returned %s", id, truncID)
+	}
+}
+
+func TestShortenIdInvalid(t *testing.T) {
+	id := "1234"
+	truncID := TruncateID(id)
+	if len(truncID) != len(id) {
+		t.Fatalf("Id returned is incorrect: truncate on %s returned %s", id, truncID)
+	}
+}
+
+func TestGenerateRandomID(t *testing.T) {
+	id := GenerateRandomID()
+
+	if len(id) != 64 {
+		t.Fatalf("Id returned is incorrect: %s", id)
+	}
+}
+
+func TestRandomString(t *testing.T) {
+	id := RandomString()
+	if len(id) != 64 {
+		t.Fatalf("Id returned is incorrect: %s", id)
+	}
+}
+
+func TestRandomStringUniqueness(t *testing.T) {
+	repeats := 25
+	set := make(map[string]struct{}, repeats)
+	for i := 0; i < repeats; i = i + 1 {
+		id := RandomString()
+		if len(id) != 64 {
+			t.Fatalf("Id returned is incorrect: %s", id)
+		}
+		if _, ok := set[id]; ok {
+			t.Fatalf("Random number is repeated")
+		}
+		set[id] = struct{}{}
+	}
+}