Fix connection cache eviction

MANIFEST

@@ -18,6 +18,7 @@ lib/Net/OpenSSH/ShellQuoter/MSCmd.pm
 lib/Net/OpenSSH/ShellQuoter/Chain.pm
 lib/Net/OpenSSH/ObjectRemote.pm
 t/common.pm
+t/connection-cache.t
 t/test_server_key
 t/test_server_key.pub
 t/test_user_key

lib/Net/OpenSSH/ConnectionCache.pm

@@ -29,10 +29,10 @@ sub _factory {
     if ($MAX_SIZE <= keys %cache) {
         for (keys %cache) {
             $ssh = $cache{$_};
-            $ssh or $ssh->error != OSSH_MASTER_FAILED or delete $cache{$_}
+            delete $cache{$_} unless $ssh and $ssh->error != OSSH_MASTER_FAILED;
         }
         for (keys %cache) {
-            last if ($MAX_SIZE <= keys %cache);
+            last if (keys %cache < $MAX_SIZE);
             weaken $cache{$_};
             if (defined $cache{$_}) {
                 $cache{$_} = $cache{$_}; # unweaken

t/connection-cache.t

@@ -0,0 +1,46 @@
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+
+use Test::More tests => 7;
+use Net::OpenSSH::Constants qw(OSSH_MASTER_FAILED);
+use Net::OpenSSH::ConnectionCache;
+
+{
+    package Test::Net::OpenSSH::ConnectionCache::SSH;
+
+    sub new {
+        my $class = shift;
+        return bless { @_ }, $class;
+    }
+
+    sub error { shift->{error} || 0 }
+    sub wait_for_master { 1 }
+}
+
+local $Net::OpenSSH::ConnectionCache::MAX_SIZE = 2;
+local %Net::OpenSSH::ConnectionCache::cache = (
+    live   => Test::Net::OpenSSH::ConnectionCache::SSH->new(error => 0),
+    failed => Test::Net::OpenSSH::ConnectionCache::SSH->new(error => OSSH_MASTER_FAILED),
+    empty  => undef,
+);
+
+my $ssh;
+eval {
+    $ssh = Net::OpenSSH::ConnectionCache::_factory(
+        'Test::Net::OpenSSH::ConnectionCache::SSH',
+        host => 'cache-test-host'
+    );
+};
+
+is($@, '', 'cache cleanup does not die on empty entries');
+ok($ssh, 'factory returns a new object');
+ok(!exists $Net::OpenSSH::ConnectionCache::cache{failed}, 'failed master entry is removed');
+ok(!exists $Net::OpenSSH::ConnectionCache::cache{empty}, 'empty cache entry is removed');
+ok(exists $Net::OpenSSH::ConnectionCache::cache{live}, 'live cache entry is retained');
+ok((keys %Net::OpenSSH::ConnectionCache::cache) <= $Net::OpenSSH::ConnectionCache::MAX_SIZE,
+   'cache is reduced to the configured maximum or below');
+
+Net::OpenSSH::ConnectionCache::clean_cache();
+is(scalar keys %Net::OpenSSH::ConnectionCache::cache, 0, 'clean_cache clears cache');