refactor: replace runtime asserts with proper checks

Assert statements used for runtime validation disappear under
python -O. Replace with TypeError/ValueError raises in
validate_example, TypeIdentity.of, _SourceTypeIdentityMixin,
_format_constraint, _linked_type_identity, type_collection.

Guard _find_common_base against empty members list.
Collapse duplicate datetime.datetime/date branches.
Rename _format_field_list → _backtick_join (returns string, not list).

Author: mojodna

Makefile

@@ -17,7 +17,7 @@ test: uv-sync
 	@uv run pytest -W error packages/ -x -q --tb=short
 
 test-only:
-	@uv run pytest -W error packages/ -x
+	@uv run pytest -W error packages/ -x -q --tb=short
 
 coverage: uv-sync
 	@uv run pytest packages/ --cov overture.schema --cov-report=term --cov-report=html && open htmlcov/index.html

packages/overture-schema-codegen/src/overture/schema/codegen/extraction/examples.py

@@ -107,8 +107,9 @@ def validate_example(
     known_keys = _known_field_keys(model_fields)
     preprocessed = _inject_literal_fields(model_fields, raw)
     preprocessed = _strip_null_unknown_fields(preprocessed, known_keys)
-    result: BaseModel = TypeAdapter(validation_type).validate_python(preprocessed)
-    assert isinstance(result, BaseModel)
+    result: object = TypeAdapter(validation_type).validate_python(preprocessed)
+    if not isinstance(result, BaseModel):
+        raise TypeError(f"Expected BaseModel instance, got {type(result).__name__}")
     return result
 
 

packages/overture-schema-codegen/src/overture/schema/codegen/extraction/model_constraints.py

@@ -34,7 +34,7 @@ class _ConstraintEntry:
     field_names: frozenset[str]
 
 
-def _format_field_list(names: tuple[str, ...]) -> str:
+def _backtick_join(names: tuple[str, ...]) -> str:
     """Format field names as backtick-quoted, comma-separated list."""
     return ", ".join(f"`{n}`" for n in names)
 
@@ -73,7 +73,7 @@ def _describe_condition(condition: object) -> str:
 
 def _describe_conditional(constraint: _ConditionalConstraint) -> str:
     """Describe a require_if or forbid_if constraint."""
-    fields = _format_field_list(constraint.field_names)
+    fields = _backtick_join(constraint.field_names)
     verb = _conditional_verb(constraint)
     cond = _describe_condition(constraint.condition)
     return f"{fields} {_plural_verb(constraint.field_names)} {verb} when {cond}"
@@ -110,7 +110,7 @@ def _describe_consolidated(
 ) -> str:
     """Describe a group of consolidated conditional constraints."""
     first = constraints[0]
-    fields = _format_field_list(first.field_names)
+    fields = _backtick_join(first.field_names)
     verb = _conditional_verb(first)
     cond_field = _as_field_eq(first).field_name
     values = ", ".join(f"`{_as_field_eq(c).value}`" for c in constraints)
@@ -151,11 +151,9 @@ def _describe_one(constraint: ModelConstraint) -> str | None:
     if isinstance(constraint, NoExtraFieldsConstraint):
         return None
     if isinstance(constraint, RequireAnyOfConstraint):
-        return (
-            f"At least one of {_format_field_list(constraint.field_names)} must be set"
-        )
+        return f"At least one of {_backtick_join(constraint.field_names)} must be set"
     if isinstance(constraint, RadioGroupConstraint):
-        return f"Exactly one of {_format_field_list(constraint.field_names)} must be `true`"
+        return f"Exactly one of {_backtick_join(constraint.field_names)} must be `true`"
     if isinstance(constraint, MinFieldsSetConstraint):
         return f"At least {constraint.count} fields must be set"
     if isinstance(constraint, (RequireIfConstraint, ForbidIfConstraint)):

packages/overture-schema-codegen/src/overture/schema/codegen/extraction/specs.py

@@ -49,8 +49,10 @@ class TypeIdentity:
     @classmethod
     def of(cls, obj: object) -> TypeIdentity:
         """Derive a TypeIdentity from a named object (class, NewType, etc.)."""
-        assert obj is not None
-        return cls(obj, obj.__name__)  # type: ignore[attr-defined]
+        name = getattr(obj, "__name__", None)
+        if name is None:
+            raise TypeError(f"Cannot derive TypeIdentity from {obj!r}: no __name__")
+        return cls(obj, name)
 
     def __eq__(self, other: object) -> bool:
         return isinstance(other, TypeIdentity) and self.obj is other.obj
@@ -78,7 +80,8 @@ class _SourceTypeIdentityMixin:
 
     @property
     def identity(self) -> TypeIdentity:
-        assert self.source_type is not None
+        if self.source_type is None:
+            raise ValueError(f"Cannot derive identity for {self.name}: no source_type")
         return TypeIdentity(self.source_type, self.name)
 
 

packages/overture-schema-codegen/src/overture/schema/codegen/extraction/union_extraction.py

@@ -18,6 +18,8 @@
 
 def _find_common_base(members: list[type[BaseModel]]) -> type[BaseModel]:
     """Find the most-derived common BaseModel ancestor of all members."""
+    if not members:
+        raise ValueError("Cannot find common base of empty members list")
     filtered_mros = [
         [c for c in cls.__mro__ if is_model_class(c) and c is not BaseModel]
         for cls in members

packages/overture-schema-codegen/src/overture/schema/codegen/layout/type_collection.py

@@ -109,7 +109,10 @@ def _visit(node: TypeInfo) -> None:
                 if enum_id not in all_specs:
                     all_specs[enum_id] = extract_enum(node.source_type)
             elif is_pydantic_type(node):
-                assert node.source_type is not None  # guaranteed by is_pydantic_type
+                if node.source_type is None:
+                    raise TypeError(
+                        "is_pydantic_type returned True but source_type is None"
+                    )
                 pid = TypeIdentity.of(node.source_type)
                 if pid not in all_specs:
                     all_specs[pid] = extract_pydantic_type(node.source_type)

packages/overture-schema-codegen/src/overture/schema/codegen/markdown/renderer.py

@@ -174,9 +174,6 @@ def _format_example_value(value: object) -> str:
     if isinstance(value, bool):
         return "`true`" if value else "`false`"
 
-    if isinstance(value, datetime.datetime):
-        return f"`{value.isoformat()}`"
-
     if isinstance(value, datetime.date):
         return f"`{value.isoformat()}`"
 
@@ -456,7 +453,9 @@ def _format_constraint(
     if cs.source_ref is None or cs.source_ref is newtype_ref:
         return _NewTypeConstraintRow(display=display)
 
-    assert cs.source_name is not None  # source_ref and source_name are set together
+    # source_ref and source_name are always set together
+    if cs.source_name is None:
+        return _NewTypeConstraintRow(display=display)
     source_identity = TypeIdentity(cs.source_ref, cs.source_name)
     source_link = ctx.resolve_link(source_identity) if ctx else None
     return _NewTypeConstraintRow(

packages/overture-schema-codegen/src/overture/schema/codegen/markdown/type_format.py

@@ -54,8 +54,11 @@ def _plain_list_type(base: str, depth: int) -> str:
 
 def _linked_type_identity(ti: TypeInfo) -> TypeIdentity | None:
     """Return the TypeIdentity to use for a markdown link, or None for non-linked types."""
-    if is_semantic_newtype(ti) and ti.newtype_ref is not None:
-        assert ti.newtype_name is not None  # guaranteed by is_semantic_newtype
+    if (
+        is_semantic_newtype(ti)
+        and ti.newtype_ref is not None
+        and ti.newtype_name is not None
+    ):
         return TypeIdentity(ti.newtype_ref, ti.newtype_name)
     if ti.kind in (TypeKind.ENUM, TypeKind.MODEL) and ti.source_type is not None:
         return TypeIdentity(ti.source_type, ti.base_type)
@@ -148,7 +151,6 @@ def format_type(
         # qualifier instead (e.g., Sources wrapping list[SourceItem] renders as
         # Sources (list)), since the list-ness is an implementation detail of the type.
         if ti.newtype_outer_list_depth > 0:
-            assert ti.is_list  # outer list layers are a subset of total list layers
             display = _wrap_list_n(display, ti.newtype_outer_list_depth)
         elif ti.is_list and ti.newtype_name is not None:  # list is inside the NewType
             qualifiers.append("list")