Default options: use first item from supported values

Instead of repeating the values as the default for a given option,
let's just use the first entry for each of the supported values list.
Signed-off-by: NCleber Rosa <crosa@redhat.com>

avocado_vt/options.py

@@ -89,13 +89,14 @@ class VirtTestOptionsProcess(object):
         set_opt(self.options, 'vt_smp',
                 settings.get_value('vt.qemu', 'smp', default='2'))
         set_opt(self.options, 'vt_image_type',
-                settings.get_value('vt.qemu', 'image_type', default='qcow2'))
+                settings.get_value('vt.qemu', 'image_type',
+                                   default=SUPPORTED_IMAGE_TYPES[0]))
         set_opt(self.options, 'vt_nic_model',
                 settings.get_value('vt.qemu', 'nic_model',
-                                   default='virtio_net'))
+                                   default=SUPPORTED_NIC_MODELS[0]))
         set_opt(self.options, 'vt_disk_bus',
                 settings.get_value('vt.qemu', 'disk_bus',
-                                   default='virtio_blk'))
+                                   default=SUPPORTED_DISK_BUSES[0]))
         set_opt(self.options, 'vt_qemu_sandbox',
                 settings.get_value('vt.qemu', 'sandbox', default='on'))
         set_opt(self.options, 'vt_qemu_defconfig',

avocado_vt/plugins/vt.py

@@ -53,7 +53,7 @@ def add_basic_vt_options(parser):
     msg = ("Choose test type (%s). Default: %%(default)s" %
            ", ".join(SUPPORTED_TEST_TYPES))
     parser.add_argument("--vt-type", action="store", dest="vt_type",
-                        help=msg, default='qemu')
+                        help=msg, default=SUPPORTED_TEST_TYPES[0])
     arch = settings.get_value('vt.common', 'arch', default=None)
     parser.add_argument("--vt-arch", help="Choose the VM architecture. "
                         "Default: %(default)s", default=arch)

virttest/standalone_test.py

@@ -21,14 +21,18 @@ def _variant_only_file(filename):
                       if not _.lstrip().startswith('#')])
 
 
+#: The first entry of these lists will be used as a default value.
+#: Only change the first entry if you intend to change the default
+#: value.  See :func:`avocado_vt.plugins.vt.add_basic_vt_options` and
+#: class:`avocado_vt.options.VirtTestOptionsProcess` for usage examples.
 SUPPORTED_TEST_TYPES = [
     'qemu', 'libvirt', 'libguestfs', 'openvswitch', 'v2v', 'lvsb', 'spice']
 
 SUPPORTED_LIBVIRT_URIS = ['qemu:///system', 'lxc:///']
 SUPPORTED_LIBVIRT_DRIVERS = ['qemu', 'lxc', 'xen']
 
-SUPPORTED_IMAGE_TYPES = ['raw', 'qcow2', 'qed', 'vmdk']
-SUPPORTED_DISK_BUSES = ['ide', 'scsi', 'virtio_blk',
+SUPPORTED_IMAGE_TYPES = ['qcow2', 'raw', 'qed', 'vmdk']
+SUPPORTED_DISK_BUSES = ['virtio_blk', 'ide', 'scsi',
                         'virtio_scsi', 'lsi_scsi', 'ahci', 'usb2', 'xenblk']
 SUPPORTED_NIC_MODELS = ["virtio_net", "e1000", "rtl8139", "spapr-vlan"]
 SUPPORTED_NET_TYPES = ["bridge", "user", "none"]