Add a fifth unit test.

src/or/dns.c

@@ -2118,5 +2118,18 @@ assert_cache_ok_(void)
       }
     });
 }
+
 #endif
 
+cached_resolve_t
+*dns_get_cache_entry(cached_resolve_t *query)
+{
+  return HT_FIND(cache_map, &cache_root, query);
+}
+
+void
+dns_insert_cache_entry(cached_resolve_t *new_entry)
+{
+  HT_INSERT(cache_map, &cache_root, new_entry);
+}
+

src/or/dns.h

@@ -42,6 +42,10 @@ uint8_t answer_type,const cached_resolve_t *resolved));
 
 MOCK_DECL(STATIC void,send_resolved_hostname_cell,(edge_connection_t *conn,
 const char *hostname));
+
+cached_resolve_t *dns_get_cache_entry(cached_resolve_t *query);
+void dns_insert_cache_entry(cached_resolve_t *new_entry);
+
 #endif
 
 #endif

src/test/test_dns.c

@@ -513,12 +513,62 @@ NS(test_main)(void *arg)
 
 #define NS_SUBMODULE ASPECT(resolve_impl, cache_hit_pending)
 
+/* Given that there is already a pending resolve for the given address,
+ * we want dns_resolve_impl to append our exit connection to list
+ * of pending connections for the pending DNS request and return 0.
+ */
+
+static int
+NS(router_my_exit_policy_is_reject_star)(void)
+{
+  return 0;
+}
+
 static void
 NS(test_main)(void *arg)
 {
-  tt_skip();
+  int retval;
+  int made_pending = 0;
+
+  pending_connection_t *pending_conn = NULL;
+
+  edge_connection_t *exitconn = create_valid_exitconn();
+  or_circuit_t *on_circ = tor_malloc_zero(sizeof(or_circuit_t));
+
+  cached_resolve_t *cache_entry = tor_malloc_zero(sizeof(cached_resolve_t));
+  cache_entry->magic = CACHED_RESOLVE_MAGIC;
+  cache_entry->state = CACHE_STATE_PENDING;
+  cache_entry->minheap_idx = -1;
+  cache_entry->expire = time(NULL) + 60 * 60;
+
+  TO_CONN(exitconn)->address = tor_strdup("torproject.org");
+
+  strlcpy(cache_entry->address, TO_CONN(exitconn)->address,
+          sizeof(cache_entry->address));
+
+  NS_MOCK(router_my_exit_policy_is_reject_star);
+
+  dns_init();
+
+  dns_insert_cache_entry(cache_entry);
+
+  retval = dns_resolve_impl(exitconn, 1, on_circ, NULL, &made_pending,
+                            NULL);
+
+  tt_int_op(retval,==,0);
+  tt_int_op(made_pending,==,1);
+
+  pending_conn = cache_entry->pending_connections;
+
+  tt_assert(pending_conn != NULL);
+  tt_assert(pending_conn->conn == exitconn);
 
   done:
+  NS_UNMOCK(router_my_exit_policy_is_reject_star);
+  tor_free(on_circ);
+  tor_free(TO_CONN(exitconn)->address);
+  tor_free(cache_entry->pending_connections);
+  tor_free(cache_entry);
   return;
 }