Encountered this problem in running Oprofile's control script (opcontrol) on BusyBox 1.11.2.

This shows up when you use the single character option, for instance  "-d" instead of the "--dump" option. The problem occurs when you do

if test -z "$2" -a "$1" = "--reset";  then

running with -xv option I see using the "-d" option

+ test -z  -a -d = --reset                        <<<<<<<<<< $2  evaluates to null, $1 evaluates to -d
sh: --reset: unknown operand          
+ load_module

running with -xv option I see using the "--dump" option

+ test -z  -a --dump = --reset                <<<<<<<<<< $2 evaluates  to null, $1 evaluates to --dump
+ load_module

I tried as an alternative

if [  \( -z "$2"\) -a \("$1" = "--reset" \) ]; then

but using either the -d or --dump option I got
+ [ ( -z ) -a (-d = --reset) ]
sh: closing paren expected      

The only workaround that works is:

 if test \( -z "$2"\) -a \("$1" = "--reset" \) ; then

+ test ( -z ) -a (-d = --reset )                 <<<<<<<<<< $2  evaluates to null, $1 evaluates to -d
+ load_module

+ test ( -z ) -a (--dump = --reset )      <<<<<<<<<< $2  evaluates to null, $1 evaluates to --dump
+ load_module