fix: reworking some code smell issues

test/bds/strings_test.exs

@@ -0,0 +1,12 @@
+defmodule BDS.StringsTest do
+  use ExUnit.Case, async: true
+
+  alias BDS.Strings
+
+  test "pad2/1 zero-pads to at least two digits" do
+    assert Strings.pad2(0) == "00"
+    assert Strings.pad2(3) == "03"
+    assert Strings.pad2(12) == "12"
+    assert Strings.pad2(123) == "123"
+  end
+end