moved zero pad

internal/common/strings.go

@@ -1,6 +1,7 @@
 package common
 
 import (
+	"strconv"
 	"strings"
 )
 
@@ -12,3 +13,11 @@ func Unify(s string) string {
 	}
 	return s
 }
+
+func ZeroPad(num int, length int) string {
+	str := strconv.Itoa(num)
+	if len(str) >= length {
+		return str
+	}
+	return strings.Repeat("0", length-len(str)) + str
+}

internal/common/strings_test.go

@@ -35,3 +35,18 @@ func TestUnify(t *testing.T) {
 		t.Errorf(`Double whitespaces need to be removed`)
 	}
 }
+
+func TestZeroPad(t *testing.T) {
+	cases := map[int]string{
+		0:    "000",
+		5:    "005",
+		1000: "1000",
+		50:   "050",
+	}
+
+	for key, val := range cases {
+		if res := ZeroPad(key, 3); res != val {
+			t.Errorf(`did not match`)
+		}
+	}
+}