if( $line =~ m[^REM $sTest\s*$]i ) {
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If you use the //, then you don't need the "m" in front, but otherwise its just style preference.

There is one other fine point about this, if $sTest could contain some characters that would normally mean something to the regex engine, like a "(" or whatever, you can specify to interpret the string $sTest literally - meaning ignore the meaning of those characters. This is done by surrounding $sTest with a \Q \E pair.

if( $line =~ /^REM \Q$sTest\E\s*$/i ) {
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