Merge pull request #537 from janosh/fix-decompress_file

Fix `decompress_file()` if no compressed file found

monty/shutil.py

@@ -93,28 +93,27 @@ def compress_dir(path, compression="gz"):
             compress_file(os.path.join(parent, f), compression=compression)
 
 
-def decompress_file(filepath) -> str:
+def decompress_file(filepath) -> str | None:
     """
     Decompresses a file with the correct extension. Automatically detects
     gz, bz2 or z extension.
 
     Args:
         filepath (str): Path to file.
-        compression (str): A compression mode. Valid options are "gz" or
-            "bz2". Defaults to "gz".
 
     Returns:
         str: The decompressed file path.
     """
     toks = filepath.split(".")
     file_ext = toks[-1].upper()
-    if file_ext in ["BZ2", "GZ", "Z"]:
-        out_file = ".".join(toks[0:-1])
-        with zopen(filepath, "rb") as f_in, open(out_file, "wb") as f_out:
+    if file_ext in ["BZ2", "GZ", "Z"] and os.path.isfile(filepath):
+        decompressed_file = ".".join(toks[0:-1])
+        with zopen(filepath, "rb") as f_in, open(decompressed_file, "wb") as f_out:
             f_out.writelines(f_in)
         os.remove(filepath)
 
-    return out_file
+        return decompressed_file
+    return None
 
 
 def decompress_dir(path):

tests/test_shutil.py

@@ -67,6 +67,11 @@ def test_compress_and_decompress_file(self):
             self.assertEqual(txt, "hello world")
         self.assertRaises(ValueError, compress_file, "whatever", "badformat")
 
+        # test decompress non-existent/non-compressed file
+        self.assertIsNone(decompress_file("non-existent"))
+        self.assertIsNone(decompress_file("non-existent.gz"))
+        self.assertIsNone(decompress_file("non-existent.bz2"))
+
     def tearDown(self):
         os.remove(os.path.join(test_dir, "tempfile"))