support/testing: add runtime tests for python-scp

Add a basic test involving a local SSH connection (based on dropbear
server). The test validates that we are able, through python-scp, to
fetch the /etc/hostname file.

The test needs some basic key initialization to allow connecting to the
dropbear server, hence the custom run_sample_scripts method.

Signed-off-by: Alexis Lothoré <alexis.lothore@bootlin.com>
[Julien:
 - remove unneeded os import in test script
 - execute setup commands with assertRunOk()
 - create /root/.ssh with 0700 mode
 - run sample scripts using super()
 - check in the sample file that copied files are the same
]
Signed-off-by: Julien Olivain <ju.o@free.fr>

support/testing/tests/package/sample_python_scp.py

@@ -0,0 +1,15 @@
+import filecmp
+
+from paramiko import SSHClient
+from paramiko.client import AutoAddPolicy
+
+from scp import SCPClient
+
+ssh_client = SSHClient()
+ssh_client.load_system_host_keys()
+ssh_client.set_missing_host_key_policy(AutoAddPolicy)
+ssh_client.connect('127.0.0.1', username='root')
+scp_client = SCPClient(ssh_client.get_transport())
+scp_client.get("/etc/hostname", "/tmp/hostname")
+
+assert filecmp("/etc/hostname", "/tmp/hostname")