Change: Extract checking a plugin for validity to a separate function

Add a reusable function to check if a Python module is a valid autohooks
precommit plugin.

autohooks/cli/check.py

@@ -25,10 +25,10 @@
 )
 from autohooks.hooks import PreCommitHook
 from autohooks.precommit.run import (
+    CheckPluginError,
+    CheckPluginWarning,
     autohooks_module_path,
-    has_precommit_function,
-    has_precommit_parameters,
-    load_plugin,
+    check_plugin,
 )
 from autohooks.settings import Mode
 from autohooks.terminal import Terminal
@@ -134,24 +134,13 @@ def check_config(
             else:
                 with autohooks_module_path():
                     for name in plugins:
-                        try:
-                            plugin = load_plugin(name)
-                            if not has_precommit_function(plugin):
-                                term.error(
-                                    f'Plugin "{name}" has no precommit '
-                                    "function. The function is required to run"
-                                    " the plugin as git pre commit hook."
-                                )
-                            elif not has_precommit_parameters(plugin):
-                                term.warning(
-                                    f'Plugin "{name}" uses a deprecated '
-                                    "signature for its precommit function. It "
-                                    "is missing the **kwargs parameter."
-                                )
+                        result = check_plugin(name)
+                        if result:
+                            if isinstance(result, CheckPluginError):
+                                term.error(str(result))
+                            elif isinstance(result, CheckPluginWarning):
+                                term.warning(str(result))
                             else:
-                                term.ok(f'Plugin "{name}" active and loadable.')
-                        except ImportError as e:
-                            term.error(
-                                f'"{name}" is not a valid autohooks '
-                                f"plugin. {e}"
-                            )
+                                term.info(str(result))
+                        else:
+                            term.ok(f'Plugin "{name}" active and loadable.')

autohooks/precommit/run.py

@@ -75,6 +75,53 @@ def check_hook_mode(term: Terminal, config_mode: Mode, hook_mode: Mode) -> None:
         )
 
 
+class CheckPluginResult:
+    def __init__(self, message: str) -> None:
+        self.message = message
+
+    def __str__(self) -> str:
+        return self.message
+
+
+class CheckPluginError(CheckPluginResult):
+    """
+    Raised if a plugin check failed
+    """
+
+
+class CheckPluginWarning(CheckPluginResult):
+    """
+    Used if a plugin check raises a warning
+    """
+
+
+def check_plugin(plugin_name: str) -> Optional[CheckPluginResult]:
+    """
+    Check if a plugin (Python module) is a valid and can be used
+
+    Returns:
+        A CheckPluginResult in case of an issue with the plugin
+    """
+    try:
+        plugin = load_plugin(plugin_name)
+        if not has_precommit_function(plugin):
+            return CheckPluginError(
+                f'Plugin "{plugin_name}" has no precommit '
+                "function. The function is required to run"
+                " the plugin as git pre commit hook."
+            )
+        elif not has_precommit_parameters(plugin):
+            return CheckPluginWarning(
+                f'Plugin "{plugin_name}" uses a deprecated '
+                "signature for its precommit function. It "
+                "is missing the **kwargs parameter."
+            )
+    except ImportError as e:
+        return CheckPluginError(
+            f'"{plugin_name}" is not a valid autohooks plugin. {e}'
+        )
+
+
 class ReportProgress:
     """
     A class to report progress of a plugin

tests/precommit/__init__.py

@@ -0,0 +1,16 @@
+# Copyright (C) 2022 Greenbone Networks GmbH
+#
+# SPDX-License-Identifier: GPL-3.0-or-later
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.

tests/precommit/test_run.py

@@ -0,0 +1,77 @@
+# Copyright (C) 2022 Greenbone Networks GmbH
+#
+# SPDX-License-Identifier: GPL-3.0-or-later
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+
+import unittest
+
+from autohooks.precommit.run import (
+    CheckPluginError,
+    CheckPluginWarning,
+    check_plugin,
+)
+from tests import temp_python_module, tempdir
+
+
+class CheckPluginTestCase(unittest.TestCase):
+    def test_plugin_not_found(self):
+        with tempdir(change_into=True):
+            result = check_plugin("foo.bar")
+
+            self.assertIsInstance(result, CheckPluginError)
+            self.assertIn(
+                '"foo.bar" is not a valid autohooks plugin.', result.message
+            )
+
+    def test_no_precommit_function(self):
+        content = """print()"""
+        with temp_python_module(
+            content,
+            name="foo",
+        ):
+            result = check_plugin("foo")
+
+            self.assertIsInstance(result, CheckPluginError)
+            self.assertEqual(
+                result.message,
+                'Plugin "foo" has no precommit function. The function is '
+                "required to run the plugin as git pre commit hook.",
+            )
+
+    def test_no_precommit_function_arguments(self):
+        content = """def precommit():
+  print()"""
+        with temp_python_module(
+            content,
+            name="foo",
+        ):
+            result = check_plugin("foo")
+
+            self.assertIsInstance(result, CheckPluginWarning)
+            self.assertEqual(
+                'Plugin "foo" uses a deprecated signature for its precommit '
+                "function. It is missing the **kwargs parameter.",
+                result.message,
+            )
+
+    def test_success(self):
+        content = """def precommit(**kwargs):
+  print()"""
+        with temp_python_module(
+            content,
+            name="foo",
+        ):
+            self.assertIsNone(check_plugin("foo"))