Allow asn_lookup --update-database to create a missing database file

intelmq/bots/experts/asn_lookup/expert.py

@@ -123,10 +123,13 @@ def update_database(cls, verbose=False):
             raise MissingDependencyError("pyasn")
 
         for database_path in set(bots.values()):
-            if not Path(database_path).is_file():
-                raise ValueError('Database file does not exist or is not a file.')
-            elif not os.access(database_path, os.W_OK):
-                raise ValueError('Database file is not writeable.')
+            database_file = Path(database_path)
+            if database_file.exists():
+                if not database_file.is_file():
+                    raise ValueError('Database path exists and is not a file.')
+                if not os.access(database_path, os.W_OK):
+                    raise ValueError('Database file is not writeable.')
+            # A missing database file is fine, it will be created below.
 
         try:
             if verbose:

intelmq/tests/bots/experts/asn_lookup/test_expert.py

@@ -7,7 +7,10 @@
 Testing asn_lookup with a faked local database
 """
 
+import tempfile
 import unittest
+from pathlib import Path
+from unittest import mock
 
 import pkg_resources
 
@@ -62,5 +65,65 @@ def test_ipv6_lookup(self):
         self.assertMessageEqual(0, EXAMPLE_OUTPUT6)
 
 
+class TestASNLookupUpdateDatabase(unittest.TestCase):
+    """
+    update_database() must not reject a database file that doesn't exist yet
+    (first-time setup): the file is created by the update itself, only an
+    existing-but-unwritable file (or a path that isn't a plain file) should
+    be rejected.
+    """
+
+    def _run_with_fake_bots(self, database_path):
+        settings = {
+            'bot-1': {
+                'module': 'intelmq.bots.experts.asn_lookup.expert',
+                'parameters': {'database': str(database_path)},
+            }
+        }
+        with mock.patch(
+            'intelmq.bots.experts.asn_lookup.expert.get_bots_settings',
+            return_value=settings,
+        ):
+            with mock.patch(
+                'intelmq.bots.experts.asn_lookup.expert.pyasn',
+                new=mock.Mock(),
+            ):
+                with mock.patch(
+                    'intelmq.bots.experts.asn_lookup.expert.create_request_session',
+                    side_effect=RuntimeError('reached the network step'),
+                ):
+                    with self.assertRaises((RuntimeError, SystemExit)) as ctx:
+                        ASNLookupExpertBot.update_database(verbose=False)
+        return ctx.exception
+
+    def test_missing_database_file_is_allowed(self):
+        with tempfile.TemporaryDirectory() as tmp_dir:
+            database_path = Path(tmp_dir) / 'does-not-exist-yet' / 'ipasn.dat'
+            exc = self._run_with_fake_bots(database_path)
+        # Got past the file check and reached the (mocked) network step,
+        # instead of raising ValueError('Database file does not exist...').
+        self.assertIsInstance(exc, RuntimeError)
+
+    def test_existing_unwritable_database_file_still_rejected(self):
+        with tempfile.TemporaryDirectory() as tmp_dir:
+            database_path = Path(tmp_dir) / 'ipasn.dat'
+            database_path.touch()
+            database_path.chmod(0o400)
+            try:
+                with self.assertRaises(ValueError) as ctx:
+                    self._run_with_fake_bots(database_path)
+                self.assertIn('not writeable', str(ctx.exception))
+            finally:
+                database_path.chmod(0o600)
+
+    def test_existing_directory_as_database_path_rejected(self):
+        with tempfile.TemporaryDirectory() as tmp_dir:
+            database_path = Path(tmp_dir) / 'ipasn.dat'
+            database_path.mkdir()
+            with self.assertRaises(ValueError) as ctx:
+                self._run_with_fake_bots(database_path)
+            self.assertIn('not a file', str(ctx.exception))
+
+
 if __name__ == '__main__':  # pragma: no cover
     unittest.main()