tests: do not run qemu interface tests if the environment does not allow it

cdf73b9731 has added the qemu tests as part of the default test run,
which results in "make test" failure in more restricted environments which do not allow the
namespace creation.

Add a config flag to skip those tests, and skip them if the namespace creation fails.

Type: test
Signed-off-by: Andrew Yourtchenko <ayourtch@gmail.com>
Change-Id: Ie631f7fb2a80864f77c79619eba4a43712e950e5

test/config.py

@@ -2,6 +2,7 @@ import argparse
 import os
 import psutil
 import time
+from vpp_qemu_utils import can_create_namespaces
 
 
 def positive_int_or_default(default):
@@ -191,6 +192,11 @@ parser.add_argument(
 )
 
 parser.add_argument("--extended", action="store_true", help="run extended tests")
+parser.add_argument(
+    "--skip-netns-tests",
+    action="store_true",
+    help="skip tests involving netns operations",
+)
 
 parser.add_argument(
     "--sanity", action="store_true", help="perform sanity vpp run before running tests"
@@ -444,6 +450,10 @@ elif config.max_vpp_cpus > 0:
 else:
     max_vpp_cpus = num_cpus
 
+if not config.skip_netns_tests:
+    if not can_create_namespaces():
+        config.skip_netns_tests = True
+
 if __name__ == "__main__":
     print("Provided arguments:")
     for i in config.__dict__: