Fixed 'concurrent' inserts test

test/sqlite3_test.erl

@@ -145,15 +145,29 @@ select_many_records() ->
         1024, 
         length(rows(sqlite3:sql_exec(ct, "select * from many_records;")))).
 
-%% concurrent_inserts_test() ->
-%%     sqlite3:open(concurrent, [in_memory]), %% doing this test not in memory is much slower!
-%%     drop_table_if_exists(concurrent, t),
-%%     sqlite3:create_table(concurrent, t, [{id, integer}]),
-%%     [spawn(fun () -> sqlite3:write(concurrent, t, [{id, X}]) end) || X <- lists:seq(1, 1024)],
-%%     ?assertEqual(
-%%         1024, 
-%%         length(rows(sqlite3:read_all(concurrent, t)))),
-%%     sqlite3:close(concurrent). %% doesn't pass at the moment!
+%% note that inserts are actually serialized by gen_server
+concurrent_inserts_test() ->
+    N = 1024,
+    sqlite3:open(concurrent, [in_memory]), %% doing this test not in memory is much slower!
+    drop_table_if_exists(concurrent, t),
+    sqlite3:create_table(concurrent, t, [{id0, integer}]),
+    Self = self(),
+    [spawn(fun () ->
+               sqlite3:write(concurrent, t, [{id0, X}]),
+               Self ! {finished, N}
+           end) || X <- lists:seq(1, N)],
+    loop_concurrent_inserts(N),
+    ?assertEqual(
+        N, length(rows(sqlite3:read_all(concurrent, t)))),
+    sqlite3:close(concurrent).
+
+loop_concurrent_inserts(0) ->
+    ok;
+loop_concurrent_inserts(N) ->
+    receive
+        {finished, _} ->
+            loop_concurrent_inserts(N - 1)
+    end.
 
 nonexistent_table_info() ->
     ?assertEqual(table_does_not_exist, sqlite3:table_info(ct, nonexistent)).