Add spec for BasicSocket#local_address on Socket.pair UNIX sockets

* Also tests creating an Addrinfo with empty-path UNIX sockets.

Author: eregon

spec/ruby/library/socket/unixsocket/local_address_spec.rb

@@ -47,3 +47,50 @@
     end
   end
 end
+
+with_feature :unix_socket do
+  describe 'UNIXSocket#local_address with a UNIX socket pair' do
+    before :each do
+      @sock, @sock2 = Socket.pair(Socket::AF_UNIX, Socket::SOCK_STREAM)
+    end
+
+    after :each do
+      @sock.close
+      @sock2.close
+    end
+
+    it 'returns an Addrinfo' do
+      @sock.local_address.should be_an_instance_of(Addrinfo)
+    end
+
+    describe 'the returned Addrinfo' do
+      it 'uses AF_UNIX as the address family' do
+        @sock.local_address.afamily.should == Socket::AF_UNIX
+      end
+
+      it 'uses PF_UNIX as the protocol family' do
+        @sock.local_address.pfamily.should == Socket::PF_UNIX
+      end
+
+      it 'uses SOCK_STREAM as the socket type' do
+        @sock.local_address.socktype.should == Socket::SOCK_STREAM
+      end
+
+      it 'raises SocketError for #ip_address' do
+        -> {
+          @sock.local_address.ip_address
+        }.should raise_error(SocketError, "need IPv4 or IPv6 address")
+      end
+
+      it 'raises SocketError for #ip_port' do
+        -> {
+          @sock.local_address.ip_port
+        }.should raise_error(SocketError, "need IPv4 or IPv6 address")
+      end
+
+      it 'uses 0 as the protocol' do
+        @sock.local_address.protocol.should == 0
+      end
+    end
+  end
+end