test: cover clang-format main entry point

cpp_linter_hooks/clang_format.py

@@ -68,12 +68,12 @@ def _print_verbose_info(command: list, retval: int, output: str) -> None:
 
 def main() -> int:
     """Run clang-format as a command-line entry point."""
-    retval, output = run_clang_format()  # pragma: no cover
+    retval, output = run_clang_format()
 
-    if retval != 0 and output.strip():  # pragma: no cover
+    if retval != 0 and output.strip():
         print(output)
 
-    return retval  # pragma: no cover
+    return retval
 
 
 if __name__ == "__main__":

tests/test_clang_format.py

@@ -3,7 +3,7 @@
 
 import pytest
 
-from cpp_linter_hooks.clang_format import run_clang_format
+from cpp_linter_hooks.clang_format import main, run_clang_format
 
 
 @pytest.mark.benchmark
@@ -138,3 +138,22 @@ def test_run_clang_format_verbose_passes_version_diagnostics():
 
     assert (ret, output) == (0, "")
     mock_resolve.assert_called_once_with("clang-format", "21", True)
+
+
+def test_main_returns_success_without_output(monkeypatch, capsys):
+    monkeypatch.setattr(
+        "cpp_linter_hooks.clang_format.run_clang_format", lambda: (0, "")
+    )
+
+    assert main() == 0
+    assert capsys.readouterr().out == ""
+
+
+def test_main_prints_failure_output(monkeypatch, capsys):
+    monkeypatch.setattr(
+        "cpp_linter_hooks.clang_format.run_clang_format",
+        lambda: (1, "formatting failed"),
+    )
+
+    assert main() == 1
+    assert capsys.readouterr().out == "formatting failed\n"