Harmonize listers parameters and add test to check mandatory ones

Ensure that all lister classes have the same set of mandatory parameters
in their constructors, notably: scheduler, url, instance and credentials.

Add a new test checking listers classes have mandatory parameters declared
in their constructors. The purpose is to avoid deployment issues on staging
or production environment as celery tasks can fail to be executed if mandatory
parameters are not handled by listers.

Reated to swh/infra/sysadm-environment#5030.

swh/lister/tests/test_lister_packages.py

@@ -0,0 +1,64 @@
+# Copyright (C) 2023  The Software Heritage developers
+# See the AUTHORS file at the top-level directory of this distribution
+# License: GNU General Public License version 3, or any later version
+# See top-level LICENSE file for more information
+
+import importlib
+import inspect
+import pkgutil
+
+import pytest
+
+
+def lister_packages():
+    import swh.lister
+
+    return [
+        mod.name
+        for mod in pkgutil.iter_modules(swh.lister.__path__)
+        if mod.ispkg and mod.name != "tests"
+    ]
+
+
+@pytest.mark.parametrize("lister_package", lister_packages())
+def test_lister_has_mandatory_parameters(lister_package):
+    from swh.lister.pattern import Lister, StatelessLister
+
+    lister_mandatory_params = {
+        "scheduler",
+        "url",
+        "instance",
+        "credentials",
+        "max_origins_per_page",
+        "max_pages",
+        "enable_origins",
+    }
+
+    lister_module = importlib.import_module(f"swh.lister.{lister_package}.lister")
+    lister_module_members = inspect.getmembers(lister_module)
+    for name, obj in lister_module_members:
+        if (
+            inspect.isclass(obj)
+            and obj not in (Lister, StatelessLister)
+            and issubclass(obj, Lister)
+        ):
+            lister_params = set(inspect.getfullargspec(getattr(obj, "__init__")).args)
+
+            missing_params = lister_mandatory_params - lister_params
+
+            assert not missing_params, (
+                f"swh.lister.{lister_package}.{name} class is missing the following "
+                f"parameters in its constructor: {', '.join(missing_params)}.\n"
+                "Please add them and transmit them to the base lister class constructor "
+                f"to avoid bad surprises when deploying\nthe {lister_package} lister in "
+                "staging or production environment."
+            )
+
+
+@pytest.mark.parametrize("lister_package", lister_packages())
+def test_lister_package_has_register_function(lister_package):
+    lister_module = importlib.import_module(f"swh.lister.{lister_package}")
+    assert hasattr(lister_module, "register"), (
+        f"swh.lister.{lister_package} module is missing the register function required "
+        "to register its celery tasks in scheduler database."
+    )