diff --git a/tests.sh b/tests.sh
index f3d2eb9..8e35078 100755
--- a/tests.sh
+++ b/tests.sh
@@ -3,54 +3,58 @@
 # Note: using bash for more power in testing (the final user doesn't need it).
 
 # Global Variables
-G_NANO_VERSION="4.6.0"
-G_SHELLCHECK_VERSION="0.6.0"
+readonly G_NANO_VERSION="4.6.0"
+readonly G_SHELLCHECK_VERSION="0.6.0"
 
 # Functions
 
 # Compare Version
 # Compare the first version (x.x.x format) against second one.
-# Returns true if $1 => $2, false otherwise.
+# Returns 0 if $1 => $2, 1 otherwise.
+# In error returns 2.
 # Sources:
 #  https://unix.stackexchange.com/questions/285924/how-to-compare-a-programs-version-in-a-shell-script
 #  https://stackoverflow.com/questions/4023830/how-to-compare-two-strings-in-dot-separated-version-format-in-bash
 # Test table:
-# req   | get   | test  | res
-# ------+-------+-------+-------
-# 2.0.0 | 1.0.0 | 1.0.0 | true
-# 1.0.0 | 2.0.0 | 1.0.0 | false
-# 0.5.3 | 0.5.3 | 0.5.3 | true
+#  req   | get   | test  | res
+# -------+-------+-------+-----------
+#  2.0.0 | 1.0.0 | 1.0.0 | true  = 0
+#  1.0.0 | 2.0.0 | 1.0.0 | false = 1
+#  0.5.3 | 0.5.3 | 0.5.3 | true  = 0
 f_compare_version(){
   local required_v="$1"
   local getted_v="$2"
  
   # First: check if equal
   if [ "$required_v" = "$getted_v" ]; then
-    return true;
+    return 0;
   fi
   
   # Second: check if greater or lesser
-  local test_v=$(printf "%s\n%s" "$greater_v" "$lesser_v" | sort -V | head -n 1)
+  local test_v
+  $test_v=$(printf "%s\n%s" "$required_v" "$getted_v" | sort -V | head -n 1)
   case $test_v in
-    $getted_v) return true ;;
-    $required_v) return false ;;
-    *) return false ;;
+    $getted_v) return 0 ;;
+    $required_v) return 1 ;;
+    *) return 2 ;;
   esac
 }
 
 # Test Functions
 
 f_test_nano_version() {
-  local version="nano --version | cut -d ' ' -f 4"
-  return f_compare_version $G_NANO_VERSION $version
+  local version
+  $version=$(nano --version | cut -d ' ' -f 4)
+  return $(f_compare_version $G_NANO_VERSION $version)
 }
 
 f_test_shellcheck_version() {
-  local version="nano --version | cut -d ' ' -f 8"
-  return f_compare_version $G_SHELLCHECK_VERSION $version
+  local version
+  $version=$(nano --version | cut -d ' ' -f 8)
+  return $(f_compare_version $G_SHELLCHECK_VERSION $version)
 }
 
 f_test_nano_version
 f_test_shellcheck_version
 # ....shellcheck -f diff *.sh | git apply | git commit -a -m "Shellcheck fast corrections"
-shellcheck *.sh
+shellcheck -- *.sh