tests: replace pycodestyle with black

Drop pycodestyle for code style checking in favor of black. Black is
much faster, stable PEP8 compliant code style checker offering also
automatic formatting. It aims to be very stable and produce smallest
diffs. It's used by many small and big projects.

Running checkstyle with black takes a few seconds with a terse output.
Thus, test-checkstyle-diff is no longer necessary.

Expand scope of checkstyle to all python files in the repo, replacing
test-checkstyle with checkstyle-python.

Also, fixstyle-python is now available for automatic style formatting.

Note: python virtualenv has been consolidated in test/Makefile,
test/requirements*.txt which will eventually be moved to a central
location.  This is required to simply the automated generation of
docker executor images in the CI.

Type: improvement
Change-Id: I022a326603485f58585e879ac0f697fceefbc9c8
Signed-off-by: Klement Sekera <klement.sekera@gmail.com>
Signed-off-by: Dave Wallace <dwallacelf@gmail.com>
diff --git a/test/vpp_gre_interface.py b/test/vpp_gre_interface.py
index 770292e..9b02488 100644
--- a/test/vpp_gre_interface.py
+++ b/test/vpp_gre_interface.py
@@ -1,4 +1,3 @@
-
 from vpp_interface import VppInterface
 import socket
 from vpp_papi import VppEnum
@@ -9,10 +8,18 @@
     VPP GRE interface
     """
 
-    def __init__(self, test, src_ip, dst_ip, outer_table_id=0,
-                 type=None, mode=None, flags=0,
-                 session=0):
-        """ Create VPP GRE interface """
+    def __init__(
+        self,
+        test,
+        src_ip,
+        dst_ip,
+        outer_table_id=0,
+        type=None,
+        mode=None,
+        flags=0,
+        session=0,
+    ):
+        """Create VPP GRE interface"""
         super(VppGreInterface, self).__init__(test)
         self.t_src = src_ip
         self.t_dst = dst_ip
@@ -21,25 +28,25 @@
         self.t_flags = flags
         self.t_type = type
         if not self.t_type:
-            self.t_type = (VppEnum.vl_api_gre_tunnel_type_t.
-                           GRE_API_TUNNEL_TYPE_L3)
+            self.t_type = VppEnum.vl_api_gre_tunnel_type_t.GRE_API_TUNNEL_TYPE_L3
         self.t_mode = mode
         if not self.t_mode:
-            self.t_mode = (VppEnum.vl_api_tunnel_mode_t.
-                           TUNNEL_API_MODE_P2P)
+            self.t_mode = VppEnum.vl_api_tunnel_mode_t.TUNNEL_API_MODE_P2P
 
     def add_vpp_config(self):
         r = self.test.vapi.gre_tunnel_add_del(
             is_add=1,
             tunnel={
-                'src': self.t_src,
-                'dst': self.t_dst,
-                'outer_table_id': self.t_outer_table,
-                'instance': 0xffffffff,
-                'type': self.t_type,
-                'mode': self.t_mode,
-                'flags': self.t_flags,
-                'session_id': self.t_session})
+                "src": self.t_src,
+                "dst": self.t_dst,
+                "outer_table_id": self.t_outer_table,
+                "instance": 0xFFFFFFFF,
+                "type": self.t_type,
+                "mode": self.t_mode,
+                "flags": self.t_flags,
+                "session_id": self.t_session,
+            },
+        )
         self.set_sw_if_index(r.sw_if_index)
         self.generate_remote_hosts()
         self.test.registry.register(self, self.test.logger)
@@ -50,21 +57,22 @@
         self.test.vapi.gre_tunnel_add_del(
             is_add=0,
             tunnel={
-                'src': self.t_src,
-                'dst': self.t_dst,
-                'outer_table_id': self.t_outer_table,
-                'instance': 0xffffffff,
-                'type': self.t_type,
-                'mode': self.t_mode,
-                'flags': self.t_flags,
-                'session_id': self.t_session})
+                "src": self.t_src,
+                "dst": self.t_dst,
+                "outer_table_id": self.t_outer_table,
+                "instance": 0xFFFFFFFF,
+                "type": self.t_type,
+                "mode": self.t_mode,
+                "flags": self.t_flags,
+                "session_id": self.t_session,
+            },
+        )
 
     def object_id(self):
         return "gre-%d" % self.sw_if_index
 
     def query_vpp_config(self):
-        return (self.test.vapi.gre_tunnel_dump(
-            sw_if_index=self._sw_if_index))
+        return self.test.vapi.gre_tunnel_dump(sw_if_index=self._sw_if_index)
 
     @property
     def remote_ip(self):