fix(SKY-8799): preserve ISO datetime strings in workflow YAML loading (#5421)

tests/unit/test_yaml_loader_no_dates.py

@@ -0,0 +1,77 @@
+"""Regression tests for SKY-8799.
+
+PyYAML's default ``SafeLoader`` resolves ISO 8601 strings into Python
+``datetime`` objects. When users embed such strings inside the
+``default_value`` of a JSON workflow parameter, those values become
+``datetime`` instances on the way in and then crash ``json.dumps`` on
+the way back out, producing::
+
+    TypeError: Object of type datetime is not JSON serializable
+
+``skyvern.utils.yaml_loader.safe_load_no_dates`` removes the timestamp
+implicit resolver so the values stay as plain strings.
+"""
+
+import json
+
+import yaml
+
+from skyvern.utils.yaml_loader import safe_load_no_dates
+
+ISO_BLOB = """
+parameters:
+  - parameter_type: workflow
+    key: payload
+    workflow_parameter_type: json
+    default_value:
+      id: "12345"
+      metadata:
+        # Unquoted ISO 8601 strings are what trip the default SafeLoader.
+        created_at: 2023-10-27T10:00:00Z
+        updated_at: 2023-10-28T14:30:00Z
+        tags: ["primary", "test-data"]
+"""
+
+
+def test_default_safe_load_does_parse_datetimes() -> None:
+    # Sanity check: documents the behavior we are working around.
+    parsed = yaml.safe_load(ISO_BLOB)
+    default_value = parsed["parameters"][0]["default_value"]
+    # The default loader turns the unquoted-looking timestamps into datetimes,
+    # which is exactly what breaks downstream JSON serialization.
+    assert not isinstance(default_value["metadata"]["created_at"], str)
+
+
+def test_safe_load_no_dates_keeps_iso_strings_as_strings() -> None:
+    parsed = safe_load_no_dates(ISO_BLOB)
+    metadata = parsed["parameters"][0]["default_value"]["metadata"]
+
+    assert metadata["created_at"] == "2023-10-27T10:00:00Z"
+    assert metadata["updated_at"] == "2023-10-28T14:30:00Z"
+    assert isinstance(metadata["created_at"], str)
+    assert isinstance(metadata["updated_at"], str)
+
+
+def test_safe_load_no_dates_round_trips_through_json() -> None:
+    parsed = safe_load_no_dates(ISO_BLOB)
+    # The whole point: the parsed structure must be JSON-serializable
+    # without a custom encoder.
+    serialized = json.dumps(parsed)
+    assert "2023-10-27T10:00:00Z" in serialized
+
+
+def test_safe_load_no_dates_preserves_other_implicit_types() -> None:
+    parsed = safe_load_no_dates(
+        """
+        an_int: 42
+        a_float: 3.14
+        a_bool: true
+        a_null: null
+        a_list: [1, 2, 3]
+        """
+    )
+    assert parsed["an_int"] == 42
+    assert parsed["a_float"] == 3.14
+    assert parsed["a_bool"] is True
+    assert parsed["a_null"] is None
+    assert parsed["a_list"] == [1, 2, 3]