Added new error message and test for dict[str, Any] generation

src/assertical/fake/generator.py

@@ -487,6 +487,14 @@ def generate_class_instance(  # noqa: C901
                     f"Type {t} has property {member.name} with type {member.declared_type} that cannot be generated"
                 )
 
+        if member.collection_type in (CollectionType.REQUIRED_DICT, CollectionType.OPTIONAL_DICT):
+            if member.second_type_to_generate is None and not (
+                optional_is_none and member.collection_type == CollectionType.OPTIONAL_DICT
+            ):
+                raise Exception(
+                    f"Type {t} has property {member.name} with type {member.declared_type} that cannot be generated"
+                )
+
         generated_value: Any = None
         empty_collection: bool = False
         collection_type: Optional[CollectionType] = member.collection_type

tests/fake/test_generator_dataclass.py

@@ -3,7 +3,7 @@
 import sys
 from dataclasses import dataclass, field
 from datetime import datetime, time
-from typing import Generator, Optional
+from typing import Any, Generator, Optional
 from pathlib import Path
 
 import pytest
@@ -104,6 +104,25 @@ class DataclassWithUngeneratableType:
     generate_class_instance(DataclassWithUngeneratableType, optional_is_none=True)
 
 
+def test_dataclass_with_ungeneratable_dict_value_type():
+    """dict[str, Any] has an unresolvable value type - should raise a clear error, not crash cryptically."""
+
+    @dataclass
+    class DataclassWithUngeneratableDict:
+        d: dict[str, Any]
+
+    with pytest.raises(Exception, match="cannot be generated"):
+        generate_class_instance(DataclassWithUngeneratableDict, generate_relationships=True)
+
+    # Optional dict with optional_is_none=True should be bypassed (set to None) without raising
+    @dataclass
+    class DataclassWithOptionalUngeneratableDict:
+        d: Optional[dict[str, Any]]
+
+    result = generate_class_instance(DataclassWithOptionalUngeneratableDict, optional_is_none=True)
+    assert result.d is None
+
+
 def test_collections_dataclass():
     _ = generate_class_instance(CollectionsDataclass, seed=1, generate_relationships=True)