Adding required flags to non-default arguments in hf_argparser (#10688)

* Adding required flags to non-default arguments.

Signed-off-by: Adam Pocock <adam.pocock@oracle.com>

* make style fix.

* Update src/transformers/hf_argparser.py

Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>

Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>

tests/test_hf_argparser.py

@@ -78,6 +78,16 @@ class ListExample:
     foo_float: List[float] = list_field(default=[0.1, 0.2, 0.3])
 
 
+@dataclass
+class RequiredExample:
+    required_list: List[int] = field()
+    required_str: str = field()
+    required_enum: BasicEnum = field()
+
+    def __post_init__(self):
+        self.required_enum = BasicEnum(self.required_enum)
+
+
 class HfArgumentParserTest(unittest.TestCase):
     def argparsersEqual(self, a: argparse.ArgumentParser, b: argparse.ArgumentParser) -> bool:
         """
@@ -186,6 +196,15 @@ class HfArgumentParserTest(unittest.TestCase):
         args = parser.parse_args("--foo 12 --bar 3.14 --baz 42 --ces a b c --des 1 2 3".split())
         self.assertEqual(args, Namespace(foo=12, bar=3.14, baz="42", ces=["a", "b", "c"], des=[1, 2, 3]))
 
+    def test_with_required(self):
+        parser = HfArgumentParser(RequiredExample)
+
+        expected = argparse.ArgumentParser()
+        expected.add_argument("--required_list", nargs="+", type=int, required=True)
+        expected.add_argument("--required_str", type=str, required=True)
+        expected.add_argument("--required_enum", type=str, choices=["titi", "toto"], required=True)
+        self.argparsersEqual(parser, expected)
+
     def test_parse_dict(self):
         parser = HfArgumentParser(BasicExample)