Add conditional support for loader based plugins

The "loader" architecture has been removed in the latest Avocado
commits (and will be reflected on Avocado version 100.0 and later).

This adds a conditional support for the loader based plugins, so that
the latest Avocado-VT can still be used (hopefully for a short time)
with Avocado versions having loader support.

Fixes: avocado-framework#3591
Signed-off-by: Cleber Rosa <[email protected]>

avocado_vt/loader.py

@@ -20,7 +20,6 @@
 import logging
 import os
 
-from avocado.core import loader
 from avocado.core import output
 
 from virttest import cartesian_config
@@ -32,6 +31,12 @@
 from .discovery import DiscoveryMixIn
 from .test import VirtTest
 
+try:
+    from avocado.core import loader
+    AVOCADO_LOADER_AVAILABLE = True
+except ImportError:
+    AVOCADO_LOADER_AVAILABLE = False
+
 
 LOG = logging.getLogger("avocado.app")
 
@@ -86,107 +91,108 @@ class NotAvocadoVTTest(object):
     """
 
 
-class VirtTestLoader(loader.TestLoader, DiscoveryMixIn):
-
-    """
-    Avocado loader plugin to load avocado-vt tests
-    """
-
-    name = 'vt'
+if AVOCADO_LOADER_AVAILABLE:
+    class VirtTestLoader(loader.TestLoader, DiscoveryMixIn):
 
-    def __init__(self, config, extra_params):
-        """
-        Following extra_params are supported:
-         * avocado_vt_extra_params: Will override the "vt_extra_params"
-           of this plugins "self.config" (extends the --vt-extra-params)
         """
-        vt_extra_params = extra_params.pop("avocado_vt_extra_params", None)
-        super(VirtTestLoader, self).__init__(config, extra_params)
-        # Avocado has renamed "args" to "config" in 84ae9a5d61, lets
-        # keep making the old name available for compatibility with
-        # new and old releases
-        if hasattr(self, 'config'):
-            self.args = self.config   # pylint: disable=E0203
-        # And in case an older Avocado is used, the Loader class will
-        # contain an "args" attribute instead
-        else:
-            self.config = self.args   # pylint: disable=E0203
-        if vt_extra_params:
-            # We don't want to override the original config
-            self.config = copy.deepcopy(self.config)
-            extra = get_opt(self.config, 'vt.extra_params')
-            if extra is not None:
-                extra += vt_extra_params
-            else:
-                extra = vt_extra_params
-            set_opt(self.config, 'vt.extra_params', extra)
-
-    def get_extra_listing(self):
-        if get_opt(self.config, 'vt.list_guests'):
-            config = copy.copy(self.config)
-            set_opt(config, 'vt.config', None)
-            set_opt(config, 'vt.guest_os', None)
-            guest_listing(config)
-        if get_opt(self.config, 'vt.list_archs'):
-            config = copy.copy(self.config)
-            set_opt(config, 'vt.common.machine_type', None)
-            set_opt(config, 'vt.common.arch', None)
-            arch_listing(config)
-
-    @staticmethod
-    def get_type_label_mapping():
+        Avocado loader plugin to load avocado-vt tests
         """
-        Get label mapping for display in test listing.
 
-        :returns: a dictionary with the test class as key and description
-                  as value.
-        """
-        return {VirtTest: 'VT', NotAvocadoVTTest: "!VT"}
-
-    @staticmethod
-    def get_decorator_mapping():
-        """
-        Get label mapping for display in test listing.
+        name = 'vt'
+
+        def __init__(self, config, extra_params):
+            """
+            Following extra_params are supported:
+             * avocado_vt_extra_params: Will override the "vt_extra_params"
+               of this plugins "self.config" (extends the --vt-extra-params)
+            """
+            vt_extra_params = extra_params.pop("avocado_vt_extra_params", None)
+            super(VirtTestLoader, self).__init__(config, extra_params)
+            # Avocado has renamed "args" to "config" in 84ae9a5d61, lets
+            # keep making the old name available for compatibility with
+            # new and old releases
+            if hasattr(self, 'config'):
+                self.args = self.config   # pylint: disable=E0203
+            # And in case an older Avocado is used, the Loader class will
+            # contain an "args" attribute instead
+            else:
+                self.config = self.args   # pylint: disable=E0203
+            if vt_extra_params:
+                # We don't want to override the original config
+                self.config = copy.deepcopy(self.config)
+                extra = get_opt(self.config, 'vt.extra_params')
+                if extra is not None:
+                    extra += vt_extra_params
+                else:
+                    extra = vt_extra_params
+                set_opt(self.config, 'vt.extra_params', extra)
+
+        def get_extra_listing(self):
+            if get_opt(self.config, 'vt.list_guests'):
+                config = copy.copy(self.config)
+                set_opt(config, 'vt.config', None)
+                set_opt(config, 'vt.guest_os', None)
+                guest_listing(config)
+            if get_opt(self.config, 'vt.list_archs'):
+                config = copy.copy(self.config)
+                set_opt(config, 'vt.common.machine_type', None)
+                set_opt(config, 'vt.common.arch', None)
+                arch_listing(config)
+
+        @staticmethod
+        def get_type_label_mapping():
+            """
+            Get label mapping for display in test listing.
+
+            :returns: a dictionary with the test class as key and description
+                      as value.
+            """
+            return {VirtTest: 'VT', NotAvocadoVTTest: "!VT"}
+
+        @staticmethod
+        def get_decorator_mapping():
+            """
+            Get label mapping for display in test listing.
+
+            :return: a dictionary with the test class as key and decorator
+                     function as value.
+            """
+            term_support = output.TermSupport()
+            return {VirtTest: term_support.healthy_str,
+                    NotAvocadoVTTest: term_support.fail_header_str}
+
+        @staticmethod
+        def _report_bad_discovery(name, reason, which_tests):
+            if which_tests is loader.DiscoverMode.ALL:
+                return [(NotAvocadoVTTest, {"name": "%s: %s" % (name, reason)})]
+            else:
+                return []
 
-        :return: a dictionary with the test class as key and decorator
-                 function as value.
-        """
-        term_support = output.TermSupport()
-        return {VirtTest: term_support.healthy_str,
-                NotAvocadoVTTest: term_support.fail_header_str}
-
-    @staticmethod
-    def _report_bad_discovery(name, reason, which_tests):
-        if which_tests is loader.DiscoverMode.ALL:
-            return [(NotAvocadoVTTest, {"name": "%s: %s" % (name, reason)})]
-        else:
-            return []
-
-    def discover(self, url, which_tests=loader.DiscoverMode.DEFAULT):
-        try:
-            cartesian_parser = self._get_parser()
-            self._save_parser_cartesian_config(cartesian_parser)
-        except Exception as details:
-            return self._report_bad_discovery(url, details, which_tests)
-        if url is not None:
+        def discover(self, url, which_tests=loader.DiscoverMode.DEFAULT):
             try:
-                cartesian_parser.only_filter(url)
-            # If we have a LexerError, this means
-            # the url passed is invalid in the cartesian
-            # config parser, hence it should be ignored.
-            # just return an empty params list and let
-            # the other test plugins to handle the URL.
-            except cartesian_config.ParserError as details:
+                cartesian_parser = self._get_parser()
+                self._save_parser_cartesian_config(cartesian_parser)
+            except Exception as details:
                 return self._report_bad_discovery(url, details, which_tests)
-        elif (which_tests is loader.DiscoverMode.DEFAULT and
-              not get_opt(self.config, 'vt.config')):
-            # By default don't run anything unless vt.config provided
-            return []
-        # Create test_suite
-        test_suite = []
-        for params in (_ for _ in cartesian_parser.get_dicts()):
-            test_suite.append((VirtTest, self.convert_parameters(params)))
-        if which_tests is loader.DiscoverMode.ALL and not test_suite:
-            return self._report_bad_discovery(url, "No matching tests",
-                                              which_tests)
-        return test_suite
+            if url is not None:
+                try:
+                    cartesian_parser.only_filter(url)
+                # If we have a LexerError, this means
+                # the url passed is invalid in the cartesian
+                # config parser, hence it should be ignored.
+                # just return an empty params list and let
+                # the other test plugins to handle the URL.
+                except cartesian_config.ParserError as details:
+                    return self._report_bad_discovery(url, details, which_tests)
+            elif (which_tests is loader.DiscoverMode.DEFAULT and
+                  not get_opt(self.config, 'vt.config')):
+                # By default don't run anything unless vt.config provided
+                return []
+            # Create test_suite
+            test_suite = []
+            for params in (_ for _ in cartesian_parser.get_dicts()):
+                test_suite.append((VirtTest, self.convert_parameters(params)))
+            if which_tests is loader.DiscoverMode.ALL and not test_suite:
+                return self._report_bad_discovery(url, "No matching tests",
+                                                  which_tests)
+            return test_suite

avocado_vt/plugins/vt.py

@@ -18,7 +18,6 @@
 
 import os
 
-from avocado.core.loader import loader
 from avocado.core.plugin_interfaces import CLI
 from avocado.utils import path as utils_path
 
@@ -27,7 +26,13 @@
 from virttest.standalone_test import (SUPPORTED_LIBVIRT_URIS,
                                       SUPPORTED_TEST_TYPES)
 
-from ..loader import VirtTestLoader
+
+try:
+    from avocado.core.loader import loader
+    from ..loader import VirtTestLoader
+    AVOCADO_LOADER_AVAILABLE = True
+except ImportError:
+    AVOCADO_LOADER_AVAILABLE = False
 
 
 _PROVIDERS_DOWNLOAD_DIR = os.path.join(data_dir.get_test_providers_dir(),
@@ -226,4 +231,5 @@ def run(self, config):
         Run test modules or simple tests.
         :param config: Command line args received from the run subparser.
         """
-        loader.register_plugin(VirtTestLoader)
+        if AVOCADO_LOADER_AVAILABLE:
+            loader.register_plugin(VirtTestLoader)

avocado_vt/plugins/vt_init.py

@@ -1,7 +1,6 @@
 import importlib
 
 from avocado.core import plugin_interfaces
-from avocado.core.loader import loader
 from avocado.core.settings import settings
 from avocado.utils import path as utils_path
 
@@ -15,6 +14,13 @@
                                       SUPPORTED_TEST_TYPES,
                                       find_default_qemu_paths)
 
+try:
+    from avocado.core.loader import loader
+    AVOCADO_LOADER_AVAILABLE = True
+except ImportError:
+    AVOCADO_LOADER_AVAILABLE = False
+
+
 if hasattr(plugin_interfaces, 'Init'):
     class VtInit(plugin_interfaces.Init):
 
@@ -273,6 +279,7 @@ def initialize(self):
 
             settings.merge_with_configs()
 
-            virt_loader = getattr(importlib.import_module('avocado_vt.loader'),
-                                  'VirtTestLoader')
-            loader.register_plugin(virt_loader)
+            if AVOCADO_LOADER_AVAILABLE:
+                virt_loader = getattr(importlib.import_module('avocado_vt.loader'),
+                                      'VirtTestLoader')
+                loader.register_plugin(virt_loader)

avocado_vt/plugins/vt_list.py

@@ -19,14 +19,19 @@
 import os
 import sys
 
-from avocado.core.loader import loader
 from avocado.core.plugin_interfaces import CLI
 
 from virttest.compat import get_settings_value, add_option
 from .vt import add_basic_vt_options, add_qemu_bin_vt_option
-from ..loader import VirtTestLoader
 from virttest._wrappers import load_source
 
+try:
+    from avocado.core.loader import loader
+    from ..loader import VirtTestLoader
+    AVOCADO_LOADER_AVAILABLE = True
+except ImportError:
+    AVOCADO_LOADER_AVAILABLE = False
+
 
 # The original virt-test runner supports using autotest from a git checkout,
 # so we'll have to support that as well. The code below will pick up the
@@ -120,4 +125,5 @@ def configure(self, parser):
         add_qemu_bin_vt_option(vt_compat_group_lister)
 
     def run(self, config):
-        loader.register_plugin(VirtTestLoader)
+        if AVOCADO_LOADER_AVAILABLE:
+            loader.register_plugin(VirtTestLoader)