GH 586 bad stdin_ok prompt (#587)

src/uwtools/api/config.py

@@ -125,10 +125,12 @@ def realize(
     """
     NB: This docstring is dynamically replaced: See realize.__doc__ definition below.
     """
+    if update_config is None and update_format is not None:  # i.e. updates will be read from stdin
+        update_config = _ensure_data_source(update_config, stdin_ok)
     return _realize(
         input_config=_ensure_data_source(_str2path(input_config), stdin_ok),
         input_format=input_format,
-        update_config=_ensure_data_source(_str2path(update_config), stdin_ok),
+        update_config=_str2path(update_config),
         update_format=update_format,
         output_file=_str2path(output_file),
         output_format=output_format,

src/uwtools/tests/api/test_config.py

@@ -5,11 +5,11 @@
 from unittest.mock import patch
 
 import yaml
-from pytest import mark
+from pytest import mark, raises
 
 from uwtools.api import config
 from uwtools.config.formats.yaml import YAMLConfig
-from uwtools.exceptions import UWConfigError
+from uwtools.exceptions import UWConfigError, UWError
 from uwtools.utils.file import FORMAT
 
 
@@ -92,6 +92,31 @@ def test_realize_to_dict():
     )
 
 
+def test_realize_update_config_from_stdin():
+    with raises(UWError) as e:
+        config.realize(input_config={}, output_file="output.yaml", update_format="yaml")
+    assert str(e.value) == "Set stdin_ok=True to permit read from stdin"
+
+
+def test_realize_update_config_none():
+    input_config = {"n": 88}
+    output_file = Path("output.yaml")
+    with patch.object(config, "_realize") as _realize:
+        config.realize(input_config=input_config, output_file=output_file)
+    _realize.assert_called_once_with(
+        input_config=input_config,
+        input_format=None,
+        update_config=None,
+        update_format=None,
+        output_file=output_file,
+        output_format=None,
+        key_path=None,
+        values_needed=False,
+        total=False,
+        dry_run=False,
+    )
+
+
 @mark.parametrize("cfg", [{"foo": "bar"}, YAMLConfig(config={})])
 def test_validate(cfg):
     kwargs: dict = {"schema_file": "schema-file", "config": cfg}