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/test_http.py b/test/test_http.py
index 193eb01..30fee5b 100644
--- a/test/test_http.py
+++ b/test/test_http.py
@@ -11,7 +11,7 @@
 
 @unittest.skip("Requires root")
 class TestHttpTps(VppTestCase):
-    """ HTTP test class """
+    """HTTP test class"""
 
     @classmethod
     def setUpClass(cls):
@@ -22,21 +22,21 @@
         super(TestHttpTps, cls).tearDownClass()
 
     def setUp(self):
-        self.client_ip4 = '172.0.0.2'
-        self.server_ip4 = '172.0.0.1'
-        self.vapi.cli(f'create tap id 0 host-ip4-addr {self.client_ip4}/24')
-        self.vapi.cli(f'set int ip addr tap0 {self.server_ip4}/24')
-        self.vapi.cli('set int state tap0 up')
+        self.client_ip4 = "172.0.0.2"
+        self.server_ip4 = "172.0.0.1"
+        self.vapi.cli(f"create tap id 0 host-ip4-addr {self.client_ip4}/24")
+        self.vapi.cli(f"set int ip addr tap0 {self.server_ip4}/24")
+        self.vapi.cli("set int state tap0 up")
         self.vapi.session_enable_disable(is_enable=1)
 
     def test_http_tps(self):
-        fname = 'test_file_1M'
-        self.vapi.cli('http tps uri tcp://0.0.0.0/8080')
+        fname = "test_file_1M"
+        self.vapi.cli("http tps uri tcp://0.0.0.0/8080")
         con = http.client.HTTPConnection(f"{self.server_ip4}", 8080)
-        con.request('GET', f'/{fname}')
+        con.request("GET", f"/{fname}")
         r = con.getresponse()
         self.assertEqual(len(r.read()), 1 << 20)
 
 
-if __name__ == '__main__':
+if __name__ == "__main__":
     unittest.main(testRunner=VppTestRunner)