better error handling, fixes #60

Author: zookzook

lib/mongo/session.ex

@@ -173,6 +173,8 @@ defmodule Mongo.Session do
           {:new_connection, _server} ->
             :timer.sleep(1000)
             start_implicit_session(topology_pid, type, opts)
+          {:error, error} -> {:error, error}
+          other           -> {:error, Mongo.Error.exception("Unknow result #{inspect other} while calling Topology.checkout_session/4")}
         end
       session -> {:ok, session}
     end

lib/mongo/stream.ex

@@ -29,6 +29,7 @@ defmodule Mongo.Stream do
           true -> new(topology_pid, cmd, Keyword.put(opts, :read_counter, 2))
           false -> {:error, error}
         end
+      other -> {:error, Mongo.Error.exception("Unknow result #{inspect other} while calling Session.start_implicit_session/3")}
     end
   end
 

lib/mongo/topology.ex

@@ -271,10 +271,11 @@ defmodule Mongo.Topology do
              {server_session, new_state} <- checkout_server_session(state),
              {:ok, session}              <- Session.start_link(self(), connection, server_session, type, wire_version, opts) do
           {:reply, {:ok, session}, new_state}
+        else
+          error -> {:reply, error, state} ## in case of an error, just return the error
         end
 
       error ->
-        Logger.debug("select_servers: #{inspect error}")
         {:reply, error, state} ## in case of an error, just return the error
     end
   end

test/mongo_test.exs

@@ -25,12 +25,12 @@ defmodule Mongo.Test do
 
   test "command", c do
     assert {:ok, %{"ok" => 1.0}} = Mongo.command(c.pid, [ping: true])
-    assert {:error, %Mongo.Error{}} = Mongo.command(c.pid, [drop: "unexisting-database"])
+    assert {:error, %Mongo.Error{}} = Mongo.command(c.pid, [xdrop: "unexisting-database"])
   end
 
   test "command!", c do
     assert %{"ok" => 1.0} = Mongo.command!(c.pid, [ping: true])
-    assert_raise Mongo.Error, fn -> Mongo.command!(c.pid, [drop: "unexisting-database"]) end
+    assert_raise Mongo.Error, fn -> Mongo.command!(c.pid, [xdrop: "unexisting-database"]) end
   end
 
   test "show_collections", c do