Create Bts abstract class and make OsmoBts inherit from it

This base class will be used to describe the required accessors for all
BTS objects, be it an osmocom BTS or not.

It is introduced in this commit and will be further used in the future
when adding a NanoBts object.

Change-Id: Ic13133e61abda73a8b507c1a1bd7b98c677460f9
diff --git a/src/osmo_gsm_tester/bts_osmo.py b/src/osmo_gsm_tester/bts_osmo.py
index 5ae3392..60b9695 100644
--- a/src/osmo_gsm_tester/bts_osmo.py
+++ b/src/osmo_gsm_tester/bts_osmo.py
@@ -21,26 +21,17 @@
 import pprint
 import tempfile
 from abc import ABCMeta, abstractmethod
-from . import log, config, util, template, process, event_loop, pcu_osmo
+from . import log, config, util, template, process, event_loop, bts, pcu_osmo
 
-class OsmoBts(log.Origin, metaclass=ABCMeta):
-    suite_run = None
+class OsmoBts(bts.Bts, metaclass=ABCMeta):
     proc_bts = None
-    bsc = None
-    sgsn = None
-    lac = None
-    rac = None
-    cellid = None
-    bvci = None
     _pcu = None
 
 ##############
 # PROTECTED
 ##############
     def __init__(self, suite_run, conf, name):
-        super().__init__(log.C_RUN, name)
-        self.suite_run = suite_run
-        self.conf = conf
+        super().__init__(suite_run, conf, name)
         if len(self.pcu_socket_path().encode()) > 107:
             raise log.Error('Path for pcu socket is longer than max allowed len for unix socket path (107):', self.pcu_socket_path())
 
@@ -49,7 +40,7 @@
 ########################
     @abstractmethod
     def conf_for_bsc(self):
-        'Used by bsc objects to get path to socket.'
+        # coming from bts.Bts, we forward the implementation to children.
         pass
 
     @abstractmethod
@@ -62,19 +53,12 @@
         'Used by base class. Subclass can create different pcu implementations.'
         pass
 
-    def remote_addr(self):
-        return self.conf.get('addr')
-
-    def cleanup(self):
-        'Nothing to do by default. Subclass can override if required.'
-        pass
-
 ###################
 # PUBLIC (test API included)
 ###################
     @abstractmethod
     def start(self):
-        'Starts BTS proccess and sets self.proc_bts with an object of Process interface'
+        # coming from bts.Bts, we forward the implementation to children.
         pass
 
     def ready_for_pcu(self):
@@ -87,25 +71,6 @@
             self._pcu = self.create_pcu()
         return self._pcu
 
-    def set_bsc(self, bsc):
-        self.bsc = bsc
-
-    def set_sgsn(self, sgsn):
-        self.sgsn = sgsn
-
-    def set_lac(self, lac):
-        self.lac = lac
-
-    def set_rac(self, rac):
-        self.rac = rac
-
-    def set_cellid(self, cellid):
-        self.cellid = cellid
-
-    def set_bvci(self, bvci):
-        self.bvci = bvci
-
-
 class OsmoBtsMainUnit(OsmoBts, metaclass=ABCMeta):
 ##############
 # PROTECTED
@@ -120,6 +85,7 @@
 ########################
     @abstractmethod
     def conf_for_bsc(self):
+        # coming from bts.Bts, we forward the implementation to children.
         pass
 
     def cleanup(self):
@@ -143,4 +109,5 @@
 ###################
     @abstractmethod
     def start(self):
+        # coming from bts.Bts, we forward the implementation to children.
         pass