Add a new test to check that extras pkgs can be installed

This test gets a list of extra packages from
https://reports.xcp-ng.org/<xcp-ng-version>/extra_installable.txt
and checks that:
- the package is available and dependencies resolved using
  yumdownloader
- all packages can be installed. Before installing packages it
  saves the yum state and restores it after the installation.

Signed-off-by: Guillaume <[email protected]>

tests/packages/extra/conftest.py

@@ -0,0 +1,12 @@
+import logging
+import pytest
+import urllib.request
+
+@pytest.fixture(scope="session")
+def extra_pkgs(host):
+    version = host.xcp_version
+    url = f"https://reports.xcp-ng.org/{version}/extra_installable.txt"
+
+    logging.info(f"Getting extra packages from {url}")
+    response = urllib.request.urlopen(url)
+    return response.read().decode('utf-8').splitlines()

tests/packages/extra/test_extra_group_pkgs.py

@@ -0,0 +1,11 @@
+# Explicitly import package-scoped fixtures (see explanation in pkgfixtures.py)
+from pkgfixtures import host_with_saved_yum_state
+
+def test_extra_group_packages_url_resolved(host, extra_pkgs):
+    for p in extra_pkgs:
+        host.ssh(['yumdownloader', '--resolve', '--urls', p])
+
+def test_extra_group_packages_can_be_installed(host_with_saved_yum_state, extra_pkgs):
+    # Just try to install all packages together. Installing them one by one
+    # takes too much time due to the generation of the initrd.
+    host_with_saved_yum_state.yum_install(extra_pkgs)