my $TestText;

{
	local $/;
	open( my $in, '<', "Test.txt" ) or die "cannot open Test.txt $!";
	$TestText = <$in>;
	close $in;
}

$TestText =~ s/\Q$_\E/$hash{$_}/g for keys %hash;

open( my $out, '>', "TestFinal.txt" ) or die "cannot create TestFinal $!";
print $out $TestText;
close $out;