testutil/dbus: use a private connection in DBus test suite

DBus test suite must use a private connection to the session bus to avoid
potential problems with other code using a shared connection. Especially, avoid
using the same connecion as code under test.

Signed-off-by: Maciej Borzecki <maciej.zenon.borzecki@canonical.com>

testutil/dbustest.go

@@ -30,6 +30,24 @@ import (
 	. "gopkg.in/check.v1"
 )
 
+func dbusSessionBus() (*dbus.Conn, error) {
+	// the test suite *must* use a private connection to the bus to avoid
+	// breaking things for code that might use a shared connection
+	conn, err := dbus.SessionBusPrivate()
+	if err != nil {
+		return nil, err
+	}
+	if err := conn.Auth(nil); err != nil {
+		conn.Close()
+		return nil, err
+	}
+	if err := conn.Hello(); err != nil {
+		conn.Close()
+		return nil, err
+	}
+	return conn, nil
+}
+
 // DBusTest provides a separate dbus session bus for running tests
 type DBusTest struct {
 	tmpdir           string
@@ -63,20 +81,30 @@ func (s *DBusTest) SetUpSuite(c *C) {
 	s.oldSessionBusEnv = os.Getenv("DBUS_SESSION_BUS_ADDRESS")
 	os.Setenv("DBUS_SESSION_BUS_ADDRESS", scanner.Text())
 
-	s.SessionBus, err = dbus.SessionBus()
+	s.SessionBus, err = dbusSessionBus()
 	c.Assert(err, IsNil)
 }
 
 func (s *DBusTest) TearDownSuite(c *C) {
+	if s.SessionBus != nil {
+		s.SessionBus.Close()
+	}
+
 	os.Setenv("DBUS_SESSION_BUS_ADDRESS", s.oldSessionBusEnv)
 	if s.dbusDaemon != nil && s.dbusDaemon.Process != nil {
 		err := s.dbusDaemon.Process.Kill()
 		c.Assert(err, IsNil)
 		err = s.dbusDaemon.Wait() // do cleanup
 		c.Assert(err, ErrorMatches, `(?i)signal: killed`)
 	}
-
 }
 
 func (s *DBusTest) SetUpTest(c *C)    {}
 func (s *DBusTest) TearDownTest(c *C) {}
+
+func DBusGetConnectionUnixProcessID(conn *dbus.Conn, name string) (pid int, err error) {
+	obj := conn.Object("org.freedesktop.DBus", "/org/freedesktop/DBus")
+
+	err = obj.Call("org.freedesktop.DBus.GetConnectionUnixProcessID", 0, name).Store(&pid)
+	return pid, err
+}