Disable abbreviations on internal parser. (#477)

Author: kschwab

pydantic_settings/sources.py

@@ -1165,6 +1165,7 @@ def __init__(
                 description=None if settings_cls.__doc__ is None else dedent(settings_cls.__doc__),
                 formatter_class=formatter_class,
                 prefix_chars=self.cli_flag_prefix_char,
+                allow_abbrev=False,
             )
             if root_parser is None
             else root_parser

tests/test_source_cli.py

@@ -2223,3 +2223,17 @@ class SettingsInvalidReqCircleReqField(BaseModel):
 
     with pytest.raises(ValueError, match='mutually exclusive arguments must be optional'):
         CliApp.run(SettingsInvalidReqCircleReqField)
+
+
+def test_cli_invalid_abbrev():
+    class MySettings(BaseSettings):
+        bacon: str = ''
+        badger: str = ''
+
+    with pytest.raises(
+        SettingsError,
+        match='error parsing CLI: unrecognized arguments: --bac cli abbrev are invalid for internal parser',
+    ):
+        CliApp.run(
+            MySettings, cli_args=['--bac', 'cli abbrev are invalid for internal parser'], cli_exit_on_error=False
+        )