Fixed #1781: CLI flag shouldn't take any arguments.

CHANGELOG.md

@@ -7,6 +7,7 @@ Find out more about isort's release policy [here](https://pycqa.github.io/isort/
 ### 5.9.3 TBD
   - Improved text of skipped file message to mention gitignore feature.
   - Fixed #1779: Pylama integration ignores pylama specific isort config overrides.
+  - Fixed #1781: `--from-first` CLI flag shouldn't take any arguments.
 
 ### 5.9.2 July 8th 2021
   - Improved behavior of `isort --check --atomic` against Cython files.

isort/main.py

@@ -462,6 +462,7 @@ def _build_arg_parser() -> argparse.ArgumentParser:
         "--ff",
         "--from-first",
         dest="from_first",
+        action="store_true",
         help="Switches the typical ordering preference, "
         "showing from imports first then straight ones.",
     )

tests/unit/test_main.py

@@ -78,6 +78,7 @@ def test_parse_args():
     assert main.parse_args(["--combine-straight-imports"]) == {"combine_straight_imports": True}
     assert main.parse_args(["--dont-follow-links"]) == {"follow_links": False}
     assert main.parse_args(["--overwrite-in-place"]) == {"overwrite_in_place": True}
+    assert main.parse_args(["--from-first"]) == {"from_first": True}
 
 
 def test_ascii_art(capsys):
@@ -562,7 +563,7 @@ def test_isort_with_stdin(capsys):
 """
     )
 
-    main.main(["-", "--ff", "FROM_FIRST"], stdin=input_content)
+    main.main(["-", "--ff"], stdin=input_content)
     out, error = capsys.readouterr()
 
     assert out == (