pt-summary shouldn't leave empty files; both summary tools should

die if passed a --save-samples directory that has files in it.

t/pt-summary/pt-summary.t

@@ -13,7 +13,17 @@ use English qw(-no_match_vars);
 use PerconaTest;
 
 my ($tool) = $PROGRAM_NAME =~ m/([\w-]+)\.t$/;
-push @ARGV, "$trunk/t/$tool/*.sh" unless @ARGV;
-system("$trunk/util/test-bash-functions $trunk/bin/$tool @ARGV");
+
+use Test::More tests => 2;
+
+for my $i (2..3) {
+
+   ok(
+      no_diff(
+         sub { print `$trunk/bin/pt-summary --read-samples "$trunk/t/pt-summary/samples/Linux/00$i/" | tail -n+3` },
+         "t/pt-summary/samples/Linux/output_00$i.txt"),
+      "--read-samples samples/Linux/00$i works"
+   );
+}
 
 exit;