Support empty clang-format diff file (#2328)

bot/code_review_bot/tasks/clang_format.py

@@ -93,9 +93,15 @@ class ClangFormatTask(AnalysisTask):
         return f"`./mach clang-format -p {files}`"
 
     def parse_issues(self, artifacts, revision):
-        artifact = artifacts.get("public/code-review/clang-format.diff")
+        if "public/code-review/clang-format.diff" not in artifacts:
+            logger.warn(
+                "public/code-review/clang-format.diff is missing from artifacts"
+            )
+            return []
+
+        artifact = artifacts["public/code-review/clang-format.diff"]
         if artifact is None:
-            logger.warn("Missing clang-format.diff")
+            logger.info("Empty clang-format.diff, no patches to process")
             return []
 
         # Use all chunks provided by parsepatch

bot/tests/test_clang.py

@@ -187,6 +187,18 @@ def test_empty_patch(patch):
     assert patches == []
 
 
+def test_missing_clang_format_diff(mock_task, mock_revision, capsys):
+    """
+    Clang format task requires diff artifact to detect issues
+    """
+    task = mock_task(ClangFormatTask, "mock-clang-format")
+    assert task.parse_issues({}, mock_revision) == []
+    assert (
+        "public/code-review/clang-format.diff is missing from artifacts"
+        in capsys.readouterr().out
+    )
+
+
 def test_real_patch(mock_revision, mock_task):
     """
     Test clang format patch parsing with a real patch