Add test for __main__.py

src/pygerber/__main__.py

@@ -2,7 +2,17 @@
 
 from __future__ import annotations
 
+import os
+from contextlib import suppress
+
 from pygerber.console.commands import main
 
+if os.environ.get("COVERAGE_PROCESS_START") is not None:
+    with suppress(ImportError, ModuleNotFoundError):
+        import coverage
+
+        coverage.process_startup()
+
+
 if __name__ == "__main__":
     main()

test/unit/test_gerber/test_console/test_main.py

@@ -0,0 +1,23 @@
+from __future__ import annotations
+
+import logging
+import os
+import subprocess
+import sys
+
+
+def test_double_under_main_file() -> None:
+    result = subprocess.run(  # noqa: S603
+        [sys.executable, "-m", "pygerber"],
+        executable=sys.executable,
+        env={**os.environ, "COVERAGE_PROCESS_START": ".coveragerc"},
+        check=False,
+        capture_output=True,
+    )
+
+    logging.info(result.stdout.decode())
+    logging.error(result.stderr.decode())
+
+    assert b"--version" in result.stdout
+    assert b"--help" in result.stdout
+    assert result.returncode == 0