tests: fixed pylint errors - python 3.6.8

With the new version of python, the linter complains about quite a few
things.

1. Subprocess run should check the result of the command. In some
cases this is avoided on purpose because we expect the command to fail
with a particular status code. In these cases, the subprocess-run-check
is disabled. Also, when doing the cleanup, we don't need to check if the
cleanup is successful because we need to kill the process no matter
what.

2. Unused imports; this seems like a bug, so we just ignore pylint.

3. Unnecessary "else" after "continue" (no-else-continue); re-wrote the
if case.

4. Unnecessary "elif" after "break" (no-else-break); re-wrote the
if case.

Signed-off-by: Andreea Florescu <[email protected]>

Author: andreeaflorescu

tests/framework/http.py

@@ -1,7 +1,7 @@
 # Copyright 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 # SPDX-License-Identifier: Apache-2.0
 """Wrapper over an http session with timed requests."""
-
+# pylint: disable=unused-import
 import requests_unixsocket
 
 from framework import decorators

tests/framework/jailer.py

@@ -165,6 +165,7 @@ def setup(self):
 
     def cleanup(self):
         """Clean up this jailer context."""
+        # pylint: disable=subprocess-run-check
         shutil.rmtree(self.chroot_base_with_id(), ignore_errors=True)
 
         if self.netns:
@@ -218,6 +219,7 @@ def _kill_crgoup_tasks(self, controller):
         disappears. The retry function that calls this code makes
         sure we do not timeout.
         """
+        # pylint: disable=subprocess-run-check
         tasks_file = '/sys/fs/cgroup/{}/{}/{}/tasks'.format(
             controller,
             FC_BINARY_NAME,

tests/framework/microvm.py

@@ -124,6 +124,7 @@ def __init__(
 
     def kill(self):
         """All clean up associated with this microVM should go here."""
+        # pylint: disable=subprocess-run-check
         if self._jailer.daemonize:
             if self.jailer_clone_pid:
                 run('kill -9 {}'.format(self.jailer_clone_pid), shell=True)
@@ -253,6 +254,7 @@ def setup(self):
 
     def spawn(self):
         """Start a microVM as a daemon or in a screen session."""
+        # pylint: disable=subprocess-run-check
         self._jailer.setup()
         self._api_socket = self._jailer.api_socket_path()
         self._api_session = Session()

tests/host_tools/network.py

@@ -76,6 +76,7 @@ def _init_connection(self):
     def _exec(self, cmd):
         """Private function that handles the ssh client invocation."""
         def _exec_raw(_cmd):
+            # pylint: disable=subprocess-run-check
             cp = run([
                 "ssh",
                 "-q",
@@ -337,6 +338,7 @@ def netns(self):
 
     def __del__(self):
         """Destructor doing tap interface clean up."""
+        # pylint: disable=subprocess-run-check
         _ = run(
             'ip netns exec {} ip link set {} down'.format(
                 self.netns,

tests/integration_tests/functional/test_cpu_features.py

@@ -55,9 +55,7 @@ def _check_guest_cmd_output(test_microvm, guest_cmd, expected_header,
             if expected_header not in (None, ''):
                 if line.strip() == expected_header:
                     expected_header = None
-                    continue
-                else:
-                    continue
+                continue
 
             # See if any key matches.
             # We Use a try-catch block here since line.split() may fail.

tests/integration_tests/functional/test_rate_limiter.py

@@ -460,21 +460,24 @@ def _run_iperf_on_guest(test_microvm, iperf_cmd, hostname):
 
 def _start_local_iperf(netns_cmd_prefix):
     """Start iperf in server mode after killing any leftover iperf daemon."""
+    # pylint: disable=subprocess-run-check
     iperf_cmd = 'pkill {}\n'.format(IPERF_BINARY)
 
+    # Don't check the result of this command because it can fail if no iperf
+    # is running.
     run(iperf_cmd, shell=True)
 
     iperf_cmd = '{} {} -sD -f KBytes\n'.format(netns_cmd_prefix, IPERF_BINARY)
 
-    run(iperf_cmd, shell=True)
+    run(iperf_cmd, shell=True, check=True)
 
     # Wait for the iperf daemon to start.
     time.sleep(2)
 
 
 def _run_local_iperf(iperf_cmd):
     """Execute a client related iperf command locally."""
-    process = run(iperf_cmd, shell=True, stdout=PIPE)
+    process = run(iperf_cmd, shell=True, stdout=PIPE, check=True)
     return process.stdout.decode('utf-8')
 
 
@@ -505,6 +508,7 @@ def _process_iperf_output(iperf_out):
                 ' '
             )[0].strip()
             break
-        elif found_line > 0:
+        if found_line > 0:
+            # Skip the first 3 lines after the first line containing `------`
             found_line += 1
     return float(iperf_out_time), float(iperf_out_bw)

tests/integration_tests/security/test_seccomp.py

@@ -10,6 +10,7 @@
 def test_seccomp_ls(bin_seccomp_paths):
     """Assert that the seccomp filters deny a blacklisted syscall."""
     # pylint: disable=redefined-outer-name
+    # pylint: disable=subprocess-run-check
     # The fixture pattern causes a pylint false positive for that rule.
 
     # Path to the `ls` binary, which attempts to execute the blacklisted
@@ -34,6 +35,7 @@ def test_advanced_seccomp_harmless(bin_seccomp_paths):
     Test that the advanced demo jailer allows the harmless demo binary.
     """
     # pylint: disable=redefined-outer-name
+    # pylint: disable=subprocess-run-check
     # The fixture pattern causes a pylint false positive for that rule.
 
     demo_advanced_jailer = bin_seccomp_paths['demo_advanced_jailer']
@@ -55,6 +57,7 @@ def test_advanced_seccomp_malicious(bin_seccomp_paths):
     Test that the basic demo jailer denies the malicious demo binary.
     """
     # pylint: disable=redefined-outer-name
+    # pylint: disable=subprocess-run-check
     # The fixture pattern causes a pylint false positive for that rule.
 
     demo_advanced_jailer = bin_seccomp_paths['demo_advanced_jailer']