Bugfix: ignore-by-author-name crashes without --staged (#445)

If the user has an ignore-by-author-name rule configured, and when manually
passing a git commit message to gitlint using --msg-filename or via STDIN
without also using the --staged flag, gitlint crashes because
commit.author_name is unknown.

This fix will print a warning instead and skip the rule.

Fixes #403.

3 files changed, 26 insertions, 2 deletions

diff --git a/gitlint-core/gitlint/cli.py b/gitlint-core/gitlint/cli.py
index 32d9648..619f006 100644
--- a/gitlint-core/gitlint/cli.py
+++ b/gitlint-core/gitlint/cli.py
@@ -47,7 +47,7 @@ def setup_logging():
     # Root log, mostly used for debug
     root_log = logging.getLogger("gitlint")
     root_log.propagate = False  # Don't propagate to child loggers, the gitlint root logger handles everything
-    root_log.setLevel(logging.ERROR)
+    root_log.setLevel(logging.WARN)
     handler = logging.StreamHandler()
     formatter = logging.Formatter(LOG_FORMAT)
     handler.setFormatter(formatter)
diff --git a/gitlint-core/gitlint/rules.py b/gitlint-core/gitlint/rules.py
index 492de6d..ca4a05b 100644
--- a/gitlint-core/gitlint/rules.py
+++ b/gitlint-core/gitlint/rules.py
@@ -459,6 +459,17 @@ class IgnoreByAuthorName(ConfigurationRule):
         if not self.options["regex"].value:
             return
 
+        # If commit.author_name is not available, log warning and return
+        if commit.author_name is None:
+            warning_msg = (
+                "%s - %s: skipping - commit.author_name unknown. "
+                "Suggested fix: Use the --staged flag (or set general.staged=True in .gitlint). "
+                "More details: https://jorisroovers.com/gitlint/configuration/#staged"
+            )
+
+            self.log.warning(warning_msg, self.name, self.id)
+            return
+
         regex_method = Deprecation.get_regex_method(self, self.options["regex"])
 
         if regex_method(commit.author_name):
diff --git a/gitlint-core/gitlint/tests/rules/test_configuration_rules.py b/gitlint-core/gitlint/tests/rules/test_configuration_rules.py
index eeb74c7..d5b70a9 100644
--- a/gitlint-core/gitlint/tests/rules/test_configuration_rules.py
+++ b/gitlint-core/gitlint/tests/rules/test_configuration_rules.py
@@ -92,6 +92,19 @@ class ConfigurationRuleTests(BaseTestCase):
         self.assertEqual(config, LintConfig())
         self.assert_logged([])  # nothing logged -> nothing ignored
 
+        # No author available -> rule is skipped and warning logged
+        staged_commit = self.gitcommit("Tïtle\n\nThis is\n a relëase body\n line")
+        rule = rules.IgnoreByAuthorName({"regex": "foo"})
+        config = LintConfig()
+        rule.apply(config, staged_commit)
+        self.assertEqual(config, LintConfig())
+        expected_log_messages = [
+            "WARNING: gitlint.rules ignore-by-author-name - I4: skipping - commit.author_name unknown. "
+            "Suggested fix: Use the --staged flag (or set general.staged=True in .gitlint). "
+            "More details: https://jorisroovers.com/gitlint/configuration/#staged"
+        ]
+        self.assert_logged(expected_log_messages)
+
         # Matching regex -> expect config to ignore all rules
         rule = rules.IgnoreByAuthorName({"regex": "(.*)ëst(.*)"})
         expected_config = LintConfig()
@@ -99,7 +112,7 @@ class ConfigurationRuleTests(BaseTestCase):
         rule.apply(config, commit)
         self.assertEqual(config, expected_config)
 
-        expected_log_messages = [
+        expected_log_messages += [
             EXPECTED_REGEX_STYLE_SEARCH_DEPRECATION_WARNING.format("I4", "ignore-by-author-name"),
             "DEBUG: gitlint.rules Ignoring commit because of rule 'I4': "
             "Commit Author Name 'Tëst nåme' matches the regex '(.*)ëst(.*)',"