Refactor default block size into constant

Cargo.lock

@@ -1,5 +1,7 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
+version = 3
+
 [[package]]
 name = "aho-corasick"
 version = "0.7.18"
@@ -96,6 +98,26 @@ dependencies = [
  "unicode-width",
 ]
 
+[[package]]
+name = "const_format"
+version = "0.2.22"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "22bc6cd49b0ec407b680c3e380182b6ac63b73991cb7602de350352fc309b614"
+dependencies = [
+ "const_format_proc_macros",
+]
+
+[[package]]
+name = "const_format_proc_macros"
+version = "0.2.22"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ef196d5d972878a48da7decb7686eded338b4858fbabeed513d63a7c98b2b82d"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-xid",
+]
+
 [[package]]
 name = "difflib"
 version = "0.4.0"
@@ -141,6 +163,7 @@ dependencies = [
  "assert_cmd",
  "atty",
  "clap",
+ "const_format",
  "libc",
  "predicates",
  "thiserror",