test: improve sock_tests/move_assignment

Use also a socket for the moved-to object and check which one is closed when.

src/test/sock_tests.cpp

@@ -58,15 +58,27 @@ BOOST_AUTO_TEST_CASE(move_constructor)
 
 BOOST_AUTO_TEST_CASE(move_assignment)
 {
-    const SOCKET s = CreateSocket();
-    Sock* sock1 = new Sock(s);
-    Sock* sock2 = new Sock(INVALID_SOCKET);
+    const SOCKET s1 = CreateSocket();
+    const SOCKET s2 = CreateSocket();
+    Sock* sock1 = new Sock(s1);
+    Sock* sock2 = new Sock(s2);
+
+    BOOST_CHECK(!SocketIsClosed(s1));
+    BOOST_CHECK(!SocketIsClosed(s2));
+
     *sock2 = std::move(*sock1);
+    BOOST_CHECK(!SocketIsClosed(s1));
+    BOOST_CHECK(SocketIsClosed(s2));
+    BOOST_CHECK(*sock2 == s1);
+
     delete sock1;
-    BOOST_CHECK(!SocketIsClosed(s));
-    BOOST_CHECK(*sock2 == s);
+    BOOST_CHECK(!SocketIsClosed(s1));
+    BOOST_CHECK(SocketIsClosed(s2));
+    BOOST_CHECK(*sock2 == s1);
+
     delete sock2;
-    BOOST_CHECK(SocketIsClosed(s));
+    BOOST_CHECK(SocketIsClosed(s1));
+    BOOST_CHECK(SocketIsClosed(s2));
 }
 
 #ifndef WIN32 // Windows does not have socketpair(2).