Drop fixed_network dependency from CONF

The fixed_network module has very little dependency from config;
removing it so that it may be used by the preprov_creds module.

Change-Id: I24de72a0a997d2824b72338e31fec5329d601074
diff --git a/tempest/common/fixed_network.py b/tempest/common/fixed_network.py
index b81830a..1928a22 100644
--- a/tempest/common/fixed_network.py
+++ b/tempest/common/fixed_network.py
@@ -15,11 +15,8 @@
 
 from tempest_lib.common.utils import misc as misc_utils
 
-from tempest import config
 from tempest import exceptions
 
-CONF = config.CONF
-
 LOG = logging.getLogger(__name__)
 
 
@@ -31,14 +28,14 @@
         object to use for making the network lists api request
     :return: The full dictionary for the network in question
     :rtype: dict
-    :raises InvalidConfiguration: If the name provided is invalid, the networks
+    :raises InvalidTestResource: If the name provided is invalid, the networks
         list returns a 404, there are no found networks, or the found network
         is invalid
     """
     caller = misc_utils.find_test_caller()
 
     if not name:
-        raise exceptions.InvalidConfiguration()
+        raise exceptions.InvalidTestResource(type='network', name=name)
 
     networks = compute_networks_client.list_networks()['networks']
     networks = [n for n in networks if n['label'] == name]
@@ -53,13 +50,13 @@
         if caller:
             msg = '(%s) %s' % (caller, msg)
         LOG.warn(msg)
-        raise exceptions.InvalidConfiguration()
+        raise exceptions.InvalidTestResource(type='network', name=name)
     else:
         msg = "Network with name: %s not found" % name
         if caller:
             msg = '(%s) %s' % (caller, msg)
         LOG.warn(msg)
-        raise exceptions.InvalidConfiguration()
+        raise exceptions.InvalidTestResource(type='network', name=name)
     # To be consistent between neutron and nova network always use name even
     # if label is used in the api response. If neither is present than then
     # the returned network is invalid.
@@ -69,12 +66,13 @@
         if caller:
             msg = '(%s) %s' % (caller, msg)
         LOG.warn(msg)
-        raise exceptions.InvalidConfiguration()
+        raise exceptions.InvalidTestResource(type='network', name=name)
     network['name'] = name
     return network
 
 
-def get_tenant_network(creds_provider, compute_networks_client):
+def get_tenant_network(creds_provider, compute_networks_client,
+                       shared_network_name):
     """Get a network usable by the primary tenant
 
     :param creds_provider: instance of credential provider
@@ -83,23 +81,24 @@
            neutron and nova-network cases. If this is not an admin network
            client, set_network_kwargs might fail in case fixed_network_name
            is the network to be used, and it's not visible to the tenant
+    :param shared_network_name: name of the shared network to be used if no
+           tenant network is available in the creds provider
     :return a dict with 'id' and 'name' of the network
     """
     caller = misc_utils.find_test_caller()
-    fixed_network_name = CONF.compute.fixed_network_name
     net_creds = creds_provider.get_primary_creds()
     network = getattr(net_creds, 'network', None)
     if not network or not network.get('name'):
-        if fixed_network_name:
+        if shared_network_name:
             msg = ('No valid network provided or created, defaulting to '
                    'fixed_network_name')
             if caller:
                 msg = '(%s) %s' % (caller, msg)
             LOG.debug(msg)
             try:
-                network = get_network_from_name(fixed_network_name,
+                network = get_network_from_name(shared_network_name,
                                                 compute_networks_client)
-            except exceptions.InvalidConfiguration:
+            except exceptions.InvalidTestResource:
                 network = {}
     msg = ('Found network %s available for tenant' % network)
     if caller:
diff --git a/tempest/common/preprov_creds.py b/tempest/common/preprov_creds.py
index 5b81148..74cc3f0 100644
--- a/tempest/common/preprov_creds.py
+++ b/tempest/common/preprov_creds.py
@@ -339,7 +339,7 @@
         try:
             network = fixed_network.get_network_from_name(
                 net_name, compute_network_client)
-        except exceptions.InvalidConfiguration:
+        except exceptions.InvalidTestResource:
             network = {}
         net_creds.set_resources(network=network)
         return net_creds
diff --git a/tempest/exceptions.py b/tempest/exceptions.py
index c23e70c..031df7f 100644
--- a/tempest/exceptions.py
+++ b/tempest/exceptions.py
@@ -139,6 +139,13 @@
     message = "%(num)d cleanUp operation failed"
 
 
+# NOTE(andreaf) This exception is added here to facilitate the migration
+# of get_network_from_name and preprov_creds to tempest-lib, and it should
+# be migrated along with them
+class InvalidTestResource(TempestException):
+    message = "%(name) is not a valid %(type), or the name is ambiguous"
+
+
 class RFCViolation(RestClientException):
     message = "RFC Violation"
 
diff --git a/tempest/test.py b/tempest/test.py
index 7b508ac..a9c8ba7 100644
--- a/tempest/test.py
+++ b/tempest/test.py
@@ -612,8 +612,8 @@
             admin_creds = cred_provider.get_admin_creds()
             admin_manager = clients.Manager(admin_creds)
             networks_client = admin_manager.compute_networks_client
-        return fixed_network.get_tenant_network(cred_provider,
-                                                networks_client)
+        return fixed_network.get_tenant_network(
+            cred_provider, networks_client, CONF.compute.fixed_network_name)
 
     def assertEmpty(self, list, msg=None):
         self.assertTrue(len(list) == 0, msg)