diff --git a/README.md b/README.md
index 602299f..48e5c84 100644
--- a/README.md
+++ b/README.md
@@ -40,11 +40,19 @@ Enter the repo:
 
 Inside, do the tests:
 
-    sh scripts/test.sh
+    pandoc lua scripts/test.lua
 
 For other kind of tests, do:
 
-    sh scripts/test.sh -h
+    pandoc lua scripts/test.lua -h
+
+For other scripts, do:
+
+    pandoc lua scripts/SCRIPT
+
+For example, do:
+
+    pandoc lua scripts/make_dist.lua
 
 Contribute!
 
diff --git a/dist/lin.lua b/dist/lin.lua
index d77d203..e5311ad 100644
--- a/dist/lin.lua
+++ b/dist/lin.lua
@@ -6258,6 +6258,105 @@ do
   package.preload[module_name] = nil
 end
 local fnl = mod
+
+------------------------------------ MODS ------------------------------------
+
+-- Tries popen
+-- @param ... string: Chunks for popen
+-- @return boolean, string: Status and output of popen
+function io.try(...)
+  local cmd = table.concat({...}, " ") .. " 2>&1"
+  local handle = io.popen(cmd)
+  local output = handle:read("*a")
+  local status = (handle:close() ~= nil and true or false)
+  return status, output
+end
+
+-- Gets OS short name
+-- It is just intented to know if it is Linux, macOS or Windows.
+-- @return string: "linux" or "macos" or "windows"
+function os.uname() 
+  local status, output = io.try("uname")
+  if status then
+    output = output:gsub(" .*", ""):lower()
+    if output ~= "linux" then
+      return "macos"
+    end
+    return "linux"
+  end
+  return "windows"
+end
+
+-- Checks if OS is windows
+-- @return boolean: Windows or not
+function os.iswin()
+  return os.uname() == "windows"
+end
+
+-- Checks if OS is Unix
+-- @return boolean: Unix or not
+function os.isunix()
+  return os.uname() ~= "windows"
+end
+
+-- Changes newlines so everything is in one line
+-- @return string: String with formatted newlines as literal "\n"
+function string:linearize()
+  return self:gsub("\n", "\\\\n")
+end
+
+-- Checks if string is empty
+-- @return boolean: Empty or not
+function string:isempty()
+  return self == ''
+end
+
+function string:lstrip()
+  return self:gsub("^%s+", "")
+end
+
+function string:rstrip()
+  return self:gsub("%s+$", "")
+end
+
+function string:strip()
+  return self:lstrip():rstrip()
+end
+
+-- The following are heavily influenced by Python pathlib
+-- Check: https://docs.python.org/3/library/pathlib.html
+
+-- Checks if string is a file or directory
+-- @return boolean: Exists or not
+function string:exists()
+  return os.rename(self, self) ~= nil
+end
+
+-- Checks if string is a file
+-- @return boolean: File or not
+function string:isfile()
+  if self:exists() then
+    return io.open(self, "a+") ~= nil
+  end
+  return false
+end
+
+-- Checks if string is a directory
+-- @return boolean: Directory or not
+function string:isdir()
+  if self:exists() then
+    return io.open(self, "a+") == nil
+  end
+  return false
+end
+
+-- Reads file content
+-- @return string or nil: File content or nil
+function string:read_text()
+  if self:exists() then
+    return io.open(self):read("*a")
+  end
+end
 ----------------------------------- NATURAL -----------------------------------
 
 local nat = {}
@@ -6265,29 +6364,8 @@ local nat = {}
 function nat.get(str)
   return str
 end
-
 ----------------------------------- LITERATE ----------------------------------
 
--- Types functions extensions
-
--- Changes newlines so everything is in one line
-function string:linearize()
-  return self:gsub("\n", "\\\\n")
-end
-
--- Checks if is empty
-function string:isempty()
-  return self == ''
-end
-
--- Checks if is directory
-function string:isdir()
-  if self ~= "." and os.rename(self, self) == nil then
-    return false
-  end
-  return true
-end
-
 -- Variable for all literate stuff
 local lit = {}
 
@@ -6331,6 +6409,7 @@ function lit.checkmetatype(type, meta, key)
   local err = ""
   if type ~= mtype then
     if type == "path" then
+      -- TODO
       if not(pandoc.path.directory(mval):isdir()) then
         err = "Invalid path '" .. mval .. "' in key '" .. key .. "'"
       end
@@ -6448,7 +6527,6 @@ function lit.puts(msg, kind)
 end
 
 function lit.parseyaml(rawyaml)
-  -- TODO: avoid popen?
   local yaml = io.popen("pandoc -t json <<<\"" .. rawyaml .. "\" 2>&1")
   if yaml:read("*l"):sub(1, 1) == "{" then
     yaml = pandoc.read(rawyaml).meta
diff --git a/scripts/make_dist.lua b/scripts/make_dist.lua
new file mode 100644
index 0000000..2d7fed0
--- /dev/null
+++ b/scripts/make_dist.lua
@@ -0,0 +1,45 @@
+-- Adds Lua custom extensions
+require "../src/extensions"
+
+function make_dist()
+  -- Variables
+  local name = "lin.lua"
+  local dist = pandoc.path.join({"dist", name}) 
+  local license = string.strip([[
+Computable Pandoc & Fennel Bundle:
+  A Pandoc filter for literate and natural programming
+Computable Pandoc:
+  (C) 2023 perro hi@perrotuerto.blog
+  License: GPLv3 https://git.cuates.net/perro/computable-pandoc/src/branch/no-masters/LICENSE.txt
+  Source: https://git.cuates.net/perro/computable-pandoc
+Fennel:
+  (C) 2016-2023 Calvin Rose and contributors
+  License: MIT License https://git.sr.ht/~technomancy/fennel/tree/main/item/LICENSE
+  Source: https://sr.ht/~technomancy/fennel or https://github.com/bakpakin/Fennel/issues
+  Website: https://fennel-lang.org
+  ]])
+
+  function chomp(str, without)
+    local without = without or false
+    str = string.read_text(str):strip()
+    str = str:gsub('\n+--[^\n]+\nrequire "extensions"', "")
+    if without then
+      return str:gsub("\n[^\n]+$", "")
+    end
+    return "\n" .. str .. "\n"
+  end
+
+  local ext = chomp("src/extensions.lua")
+  local pan = chomp("src/pandoc.lua")
+  local fnl = chomp("opt/fennel.lua", true)
+  local nat = chomp("src/natural.lua", true)
+  local lit = chomp("src/literate.lua", true)
+
+  -- Bundles Fennel and Computable Pandoc
+  file = io.open(dist, "w")
+  file:write("--[[\n", license, "\n]]--\n")
+  file:write(fnl, "\nlocal fnl = mod\n", ext, nat, lit, pan)
+  file:close()
+end
+
+make_dist()
diff --git a/scripts/make_dist.sh b/scripts/make_dist.sh
deleted file mode 100644
index 8686496..0000000
--- a/scripts/make_dist.sh
+++ /dev/null
@@ -1,26 +0,0 @@
-# Makes distribution release
-
-# Variables
-NAME="lin.lua"
-DIST=dist/$NAME
-LICENSE="--[[
-Computable Pandoc & Fennel Bundle:
-  A Pandoc filter for literate and natural programming
-Computable Pandoc:
-  (C) 2023 perro hi@perrotuerto.blog
-  License: GPLv3 https://git.cuates.net/perro/computable-pandoc/src/branch/no-masters/LICENSE.txt
-  Source: https://git.cuates.net/perro/computable-pandoc
-Fennel:
-  (C) 2016-2023 Calvin Rose and contributors
-  License: MIT License https://git.sr.ht/~technomancy/fennel/tree/main/item/LICENSE
-  Source: https://sr.ht/~technomancy/fennel or https://github.com/bakpakin/Fennel/issues
-  Website: https://fennel-lang.org
-]]--"
-
-# Bundles Fennel and computable Pandoc
-(echo "$LICENSE") > $DIST
-head -n -1 opt/fennel.lua >> $DIST
-echo "local fnl = mod" >> $DIST
-head -n -1 src/natural.lua >> $DIST
-head -n -1 src/literate.lua >> $DIST
-cat src/pandoc.lua >> $DIST
diff --git a/scripts/test.lua b/scripts/test.lua
new file mode 100644
index 0000000..2f975cc
--- /dev/null
+++ b/scripts/test.lua
@@ -0,0 +1,108 @@
+-- Adds Lua custom extensions
+require "../src/extensions"
+require "../scripts/make_dist"
+
+-- Variables
+local filter = "-L dist/lin.lua"
+local verbose = ""
+local trace = "" 
+local files = {}
+local cmds = {
+  ["unix"] = {
+    ["pandoc"] = "pandoc ",
+    ["clear"] = "clear ",
+    ["ls"] = "ls ",
+  },
+  ["win"] = {
+    ["pandoc"] = "pandoc.exe ",
+    ["clear"] = "cls ",
+    ["ls"] = "dir ",
+  },
+}
+
+-- Prints help
+local function help()
+  local cmd = "  pandoc lua script/test.lua"
+  print(table.concat({
+    "Usage:",
+    cmd .. " [OPTIONS] [FILES]",
+    "Options",
+    "  -V  --verbose  Prints verbose debbuging output",
+    "  -t  --trace    Prints diagnostic output tracing parser progress",
+    "  -h  --help     Prints this help",
+    "Examples:",
+    cmd .. "                  Tests for 'tests/*.*",
+    cmd .. " -V               Verbose tests for 'tests/*.*'",
+    cmd .. " -t               Tests and tracing for 'tests/*.*'",
+    cmd .. " tests/fail*      Tests for 'tests/fail*'",
+    cmd .. " -Vt tests/fail*  Verbose tests and tracing for 'tests/fail*'",
+    cmd .. " -h               Display this help",
+  }, "\n"))
+  os.exit()
+end
+
+-- Gets command according to OS
+local function getcmd(str)
+  local system = (os.isunix() and "unix" or "win")
+  return cmds[system][str]
+end
+
+-- Obtains result as "pass" | "fail" | "diff" (AST doesn't match)
+local function getresult(file, f, v, t)
+  local tmp, name = "tmp.json", pandoc.path.filename(file)
+  local json = pandoc.path.join({"tests", "asts", name .. ".json"})
+  local ok, out = io.try(getcmd("pandoc"), f, v, t, "-t json", "-o", tmp, file)
+  local json1, json2 = tmp:read_text(), json:read_text()
+  os.remove("tmp.json")
+  if (ok and json2 == nil) or (ok and json1 == json2) then
+    return "pass", out:strip()
+  elseif ok and json1 ~= json2 then
+    return "diff", out:strip()
+  else
+    return "fail", out:strip()
+  end
+end
+
+-- Parses args
+for _, a in ipairs(arg) do
+  if a:match("^-.*h.*") then
+    help()
+  elseif a == "-V" or a == "--verbose" then
+    verbose = "--verbose"
+  elseif a == "-t" or a == "--trace" then
+    trace = "--trace"
+  elseif a == "-Vt" or a == "-tV" then
+    verbose = "--verbose"
+    trace = "--trace"
+  elseif a:match("^-") == nil then
+    table.insert(files, pandoc.path.normalize(a))
+  end
+end
+
+-- Default files
+if #files == 0 then
+  for file in io.popen(getcmd("ls") .. "tests"):lines() do
+    if file ~= "asts" then
+      table.insert(files, pandoc.path.join({"tests", file}))
+    end
+  end
+end
+
+-- Makes distribution bundle
+make_dist()
+
+-- Clears terminal
+os.execute(getcmd("clear"))
+print "🐾 Starting tests"
+
+-- Does tests
+for _, file in ipairs(files) do
+  local expectation = pandoc.path.filename(file):gsub("%W.+$", "")
+  local result, output = getresult(file, filter, verbose, trace)
+  print("⚗️  " .. file .. ":")
+  print("  Expect: " .. expectation)
+  print("  Result: " .. result)
+  if #verbose > 0 or #trace > 0 then
+    print(output)
+  end
+end
diff --git a/scripts/test.sh b/scripts/test.sh
deleted file mode 100644
index 85a1187..0000000
--- a/scripts/test.sh
+++ /dev/null
@@ -1,71 +0,0 @@
-# Makes tests
-
-# Variables
-FILTER=dist/lin.lua
-FILES="tests/*.md"
-VERBOSE=""
-AST=false
-CMD="sh $0"
-
-# Prints help
-echo_help () {
-  echo "Usage:"
-  echo "  $CMD [-vah] [FILES]"
-  echo "Examples:"
-  echo "  $CMD                  Tests for 'tests/*.md'"
-  echo "  $CMD -v               Verbose tests for 'tests/*.md'"
-  echo "  $CMD -a               Tests and AST for 'tests/*.md'"
-  echo "  $CMD tests/fail*      Tests for 'tests/fail*'"
-  echo "  $CMD -va tests/fail*  Verbose tests and AST for 'tests/fail*'"
-  echo "  $CMD -h               Display this help"
-  exit
-}
-
-# Obtains result as "pass" | "fail" | "diff" (AST doesn't match)
-get_result () {
-  result=$([[ $1 -ne 0 ]] && echo "fail" || echo "pass")
-  if [ -f $2.json ]; then
-    diff1=$(cat tmp.json | jq)
-    diff2=$(cat $2.json | jq)
-    difference=$(diff <( printf '%s\n' "$diff1" ) <( printf '%s\n' "$diff2" ))
-    result=$([[ $? -eq 0 ]] && echo "pass" || echo "diff")
-  fi
-  echo $result
-}
-
-# Checks options
-while getopts ':vah' opt; do
-  case "$opt" in
-    v) VERBOSE="--verbose" ; shift ;;
-    a) AST=true ; shift ;;
-    h) echo_help ;;
-    ?) echo "ERROR: only -v, -a or -h is allowed" ; exit 1 ;;
-  esac
-done
-
-# Checks for files
-if [ $# -ne 0 ]; then
-  for file in $*; do
-    if [ ! -f $file ]; then
-      echo "ERROR: '$file' is not a file; do '$CMD -h' for more info" ; exit 1
-    fi
-  done
-  FILES=$*
-fi
-
-# Makes distribution bundle
-sh scripts/make_dist.sh
-
-# Does tests
-clear && echo "🐾 Starting tests"
-for file in $FILES; do
-  echo "⚗️  $file:"
-  expectation=${file:6:4}
-  ast=$(pandoc $VERBOSE -L $FILTER -t json -o tmp.json $file)
-  result=$(get_result $? $file)
-  echo "  Expect: $expectation"
-  echo "  Result: $result"
-  [ "$VERBOSE" = "--verbose" ] && echo -e "$ast"
-  [ "$AST" = true ] && pandoc -L $FILTER -t native $file
-  rm tmp.json
-done
diff --git a/src/extensions.lua b/src/extensions.lua
new file mode 100644
index 0000000..08fbee9
--- /dev/null
+++ b/src/extensions.lua
@@ -0,0 +1,98 @@
+------------------------------------ MODS ------------------------------------
+
+-- Tries popen
+-- @param ... string: Chunks for popen
+-- @return boolean, string: Status and output of popen
+function io.try(...)
+  local cmd = table.concat({...}, " ") .. " 2>&1"
+  local handle = io.popen(cmd)
+  local output = handle:read("*a")
+  local status = (handle:close() ~= nil and true or false)
+  return status, output
+end
+
+-- Gets OS short name
+-- It is just intented to know if it is Linux, macOS or Windows.
+-- @return string: "linux" or "macos" or "windows"
+function os.uname() 
+  local status, output = io.try("uname")
+  if status then
+    output = output:gsub(" .*", ""):lower()
+    if output ~= "linux" then
+      return "macos"
+    end
+    return "linux"
+  end
+  return "windows"
+end
+
+-- Checks if OS is windows
+-- @return boolean: Windows or not
+function os.iswin()
+  return os.uname() == "windows"
+end
+
+-- Checks if OS is Unix
+-- @return boolean: Unix or not
+function os.isunix()
+  return os.uname() ~= "windows"
+end
+
+-- Changes newlines so everything is in one line
+-- @return string: String with formatted newlines as literal "\n"
+function string:linearize()
+  return self:gsub("\n", "\\\\n")
+end
+
+-- Checks if string is empty
+-- @return boolean: Empty or not
+function string:isempty()
+  return self == ''
+end
+
+function string:lstrip()
+  return self:gsub("^%s+", "")
+end
+
+function string:rstrip()
+  return self:gsub("%s+$", "")
+end
+
+function string:strip()
+  return self:lstrip():rstrip()
+end
+
+-- The following are heavily influenced by Python pathlib
+-- Check: https://docs.python.org/3/library/pathlib.html
+
+-- Checks if string is a file or directory
+-- @return boolean: Exists or not
+function string:exists()
+  return os.rename(self, self) ~= nil
+end
+
+-- Checks if string is a file
+-- @return boolean: File or not
+function string:isfile()
+  if self:exists() then
+    return io.open(self, "a+") ~= nil
+  end
+  return false
+end
+
+-- Checks if string is a directory
+-- @return boolean: Directory or not
+function string:isdir()
+  if self:exists() then
+    return io.open(self, "a+") == nil
+  end
+  return false
+end
+
+-- Reads file content
+-- @return string or nil: File content or nil
+function string:read_text()
+  if self:exists() then
+    return io.open(self):read("*a")
+  end
+end
diff --git a/src/literate.lua b/src/literate.lua
index 75ce241..c3bd8d4 100644
--- a/src/literate.lua
+++ b/src/literate.lua
@@ -1,24 +1,7 @@
 ----------------------------------- LITERATE ----------------------------------
 
--- Types functions extensions
-
--- Changes newlines so everything is in one line
-function string:linearize()
-  return self:gsub("\n", "\\\\n")
-end
-
--- Checks if is empty
-function string:isempty()
-  return self == ''
-end
-
--- Checks if is directory
-function string:isdir()
-  if self ~= "." and os.rename(self, self) == nil then
-    return false
-  end
-  return true
-end
+-- Adds Lua custom extensions
+require "extensions"
 
 -- Variable for all literate stuff
 local lit = {}
@@ -63,6 +46,7 @@ function lit.checkmetatype(type, meta, key)
   local err = ""
   if type ~= mtype then
     if type == "path" then
+      -- TODO
       if not(pandoc.path.directory(mval):isdir()) then
         err = "Invalid path '" .. mval .. "' in key '" .. key .. "'"
       end
@@ -180,7 +164,6 @@ function lit.puts(msg, kind)
 end
 
 function lit.parseyaml(rawyaml)
-  -- TODO: avoid popen?
   local yaml = io.popen("pandoc -t json <<<\"" .. rawyaml .. "\" 2>&1")
   if yaml:read("*l"):sub(1, 1) == "{" then
     yaml = pandoc.read(rawyaml).meta
diff --git a/src/natural.lua b/src/natural.lua
index ace3905..57978a0 100644
--- a/src/natural.lua
+++ b/src/natural.lua
@@ -1,5 +1,8 @@
 ----------------------------------- NATURAL -----------------------------------
 
+-- Adds Lua custom extensions
+require "extensions"
+
 local nat = {}
 
 function nat.get(str)
diff --git a/tests/pass.lit.infos.md.json b/tests/asts/pass.lit.infos.md.json
similarity index 100%
rename from tests/pass.lit.infos.md.json
rename to tests/asts/pass.lit.infos.md.json
diff --git a/tests/pass.lit.warns.md.json b/tests/asts/pass.lit.warns.md.json
similarity index 100%
rename from tests/pass.lit.warns.md.json
rename to tests/asts/pass.lit.warns.md.json