CLI: reject module_paths that smell like FS paths

monkeytype/cli.py

@@ -6,6 +6,7 @@
 import argparse
 import importlib
 import inspect
+import os
 import os.path
 import runpy
 import subprocess
@@ -41,6 +42,11 @@ def module_path(path: str) -> Tuple[str, Optional[str]]:
     parts = path.split(':', 1)
     module = parts.pop(0)
     qualname = parts[0] if parts else None
+    if os.sep in module:  # Smells like a path
+        raise argparse.ArgumentTypeError(
+            f'{module} does not look like a valid Python import path'
+        )
+
     return module, qualname