tests: mock network functions so tests work with no network

There's a few places where the tests implicitly need a network
connection. Mainly, since the TDL XML test blocks in test_guest
are for a subclass of RedHatLinuxCDYumGuest and specify a URL,
we wind up hitting RedHatLinuxCDYumGuest._check_url which tries
to get the headers for the URL to figure out if the server
supports byte ranges. Let's just mock out the header retrieval
to make that method happy. Secondly, test-53-command-http-url.tdl
specifies an HTTP URL, so we wind up trying to retrieve it;
mock out the actual download, since that's not what this test is
really exercising.

Signed-off-by: Adam Williamson <awilliam@redhat.com>

Containerfile.tests.el7

@@ -4,7 +4,7 @@
 FROM quay.io/centos/centos:7
 RUN set -exo pipefail \
     && yum install -y https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm \
-    && yum install -y python-requests m2crypto libvirt-python python-lxml python-libguestfs pytest python-monotonic libvirt \
+    && yum install -y python-requests m2crypto libvirt-python python-lxml python-libguestfs pytest python-monotonic python-mock libvirt \
     && yum clean all \
     && rm -rf /var/cache/* /var/log/yum*
 

README

@@ -28,7 +28,7 @@ dnf install python3-requests python3-m2crypto python3-libvirt python3-lxml pytho
 
 If you wish to test on EL 7, make that:
 
-yum install python-requests m2crypto libvirt-python python-lxml python-libguestfs pytest python-monotonic
+yum install python-requests m2crypto libvirt-python python-lxml python-libguestfs pytest python-monotonic python-mock
 
 then run the tests:
 

tests/guest/test_guest.py

@@ -12,6 +12,10 @@
     from io import StringIO
 import logging
 import os
+try:
+    from unittest import mock
+except ImportError:
+    import mock
 
 # Find oz library
 prefix = '.'
@@ -72,7 +76,10 @@ def setup_guest(xml, macaddress=None):
         config = configparser.ConfigParser()
         config.read_file(StringIO("[libvirt]\nuri=qemu:///session\nbridge_name=%s" % route))
 
-    guest = oz.GuestFactory.guest_factory(tdl, config, None, macaddress=macaddress)
+    # mock this - it's used in RedHatLinuxCDYumGuest._check_url() -
+    # so the tests can run without a network connection
+    with mock.patch("oz.ozutil.http_get_header", return_value={}):
+        guest = oz.GuestFactory.guest_factory(tdl, config, None, macaddress=macaddress)
     return guest
 
 tdlxml = """

tests/tdl/test_tdl.py

@@ -2,6 +2,10 @@
 
 import sys
 import os
+try:
+    from unittest import mock
+except ImportError:
+    import mock
 
 try:
     import lxml.etree
@@ -97,7 +101,8 @@
 }
 
 # Test that iterates over all .tdl files
-def test_all():
+@mock.patch("oz.ozutil.http_download_file")
+def test_all(fakedl):
     for (tdl, expected_pass) in list(tests.items()):
 
         # locate full path for tdl file