feat(fixtures): fixtures multi-variant contexts, custom Enum support, and context-filtered loading (#187)

docs/module/fixtures.md

@@ -38,18 +38,20 @@ By context with [`load_fixtures_by_context`](../reference/fixtures.md#fastapi_to
 from fastapi_toolsets.fixtures import load_fixtures_by_context
 
 async with db_context() as session:
-    await load_fixtures_by_context(session=session, registry=fixtures, context=Context.TESTING)
+    await load_fixtures_by_context(session, fixtures, Context.TESTING)
 ```
 
-Directly with [`load_fixtures`](../reference/fixtures.md#fastapi_toolsets.fixtures.utils.load_fixtures):
+Directly by name with [`load_fixtures`](../reference/fixtures.md#fastapi_toolsets.fixtures.utils.load_fixtures):
 
 ```python
 from fastapi_toolsets.fixtures import load_fixtures
 
 async with db_context() as session:
-    await load_fixtures(session=session, registry=fixtures)
+    await load_fixtures(session, fixtures, "roles", "test_users")
 ```
 
+Both functions return a `dict[str, list[...]]` mapping each fixture name to the list of loaded instances.
+
 ## Contexts
 
 [`Context`](../reference/fixtures.md#fastapi_toolsets.fixtures.enum.Context) is an enum with predefined values:
@@ -58,10 +60,60 @@ async with db_context() as session:
 |---------|-------------|
 | `Context.BASE` | Core data required in all environments |
 | `Context.TESTING` | Data only loaded during tests |
+| `Context.DEVELOPMENT` | Data only loaded in development |
 | `Context.PRODUCTION` | Data only loaded in production |
 
 A fixture with no `contexts` defined takes `Context.BASE` by default.
 
+### Custom contexts
+
+Plain strings and any `Enum` subclass are accepted wherever a `Context` enum is expected.
+
+```python
+from enum import Enum
+
+class AppContext(str, Enum):
+    STAGING = "staging"
+    DEMO = "demo"
+
+@fixtures.register(contexts=[AppContext.STAGING])
+def staging_data():
+    return [Config(key="feature_x", enabled=True)]
+
+await load_fixtures_by_context(session, fixtures, AppContext.STAGING)
+```
+
+### Default context for a registry
+
+Pass `contexts` to `FixtureRegistry` to set a default for all fixtures registered in it:
+
+```python
+testing_registry = FixtureRegistry(contexts=[Context.TESTING])
+
+@testing_registry.register          # implicitly contexts=[Context.TESTING]
+def test_orders():
+    return [Order(id=1, total=99)]
+```
+
+### Same fixture name, multiple context variants
+
+The same fixture name may be registered under different (non-overlapping) context sets. When multiple contexts are loaded together, all matching variants are merged:
+
+```python
+@fixtures.register(contexts=[Context.BASE])
+def users():
+    return [User(id=1, username="admin")]
+
+@fixtures.register(contexts=[Context.TESTING])
+def users():
+    return [User(id=2, username="tester")]
+
+# loads both admin and tester
+await load_fixtures_by_context(session, fixtures, Context.BASE, Context.TESTING)
+```
+
+Registering two variants with overlapping context sets raises `ValueError`.
+
 ## Load strategies
 
 [`LoadStrategy`](../reference/fixtures.md#fastapi_toolsets.fixtures.enum.LoadStrategy) controls how the fixture loader handles rows that already exist:
@@ -69,20 +121,44 @@ A fixture with no `contexts` defined takes `Context.BASE` by default.
 | Strategy | Description |
 |----------|-------------|
 | `LoadStrategy.INSERT` | Insert only, fail on duplicates |
-| `LoadStrategy.UPSERT` | Insert or update on conflict |
+| `LoadStrategy.MERGE` | Insert or update on conflict (default) |
-| `LoadStrategy.SKIP` | Skip rows that already exist |
+| `LoadStrategy.SKIP_EXISTING` | Skip rows that already exist |
+
+```python
+await load_fixtures_by_context(
+    session, fixtures, Context.BASE, strategy=LoadStrategy.SKIP_EXISTING
+)
+```
 
 ## Merging registries
 
-Split fixtures definitions across modules and merge them:
+Split fixture definitions across modules and merge them:
 
 ```python
 from myapp.fixtures.dev import dev_fixtures
 from myapp.fixtures.prod import prod_fixtures
 
-fixtures = fixturesRegistry()
+fixtures = FixtureRegistry()
 fixtures.include_registry(registry=dev_fixtures)
 fixtures.include_registry(registry=prod_fixtures)
+```
+
+Fixtures with the same name are allowed as long as their context sets do not overlap. Conflicting contexts raise `ValueError`.
+
+## Looking up fixture instances
+
+[`get_obj_by_attr`](../reference/fixtures.md#fastapi_toolsets.fixtures.utils.get_obj_by_attr) retrieves a specific instance from a fixture function by attribute value — useful when building cross-fixture `depends_on` relationships:
+
+```python
+from fastapi_toolsets.fixtures import get_obj_by_attr
+
+@fixtures.register(depends_on=["roles"])
+def users():
+    admin_role = get_obj_by_attr(roles, "name", "admin")
+    return [User(id=1, username="alice", role_id=admin_role.id)]
+```
+
+Raises `StopIteration` if no matching instance is found.
 
 ## Pytest integration
 
@@ -111,7 +187,6 @@ async def test_user_can_login(fixture_users: list[User], fixture_roles: list[Rol
     ...
 ```
 
-
 The load order is resolved automatically from the `depends_on` declarations in your registry. Each generated fixture receives `db_session` as a dependency and returns the list of loaded model instances.
 
 ## CLI integration

src/fastapi_toolsets/fixtures/registry.py

@@ -2,6 +2,7 @@
 
 from collections.abc import Callable, Sequence
 from dataclasses import dataclass, field
+from enum import Enum
 from typing import Any, cast
 
 from sqlalchemy.orm import DeclarativeBase
@@ -12,6 +13,13 @@ from .enum import Context
 logger = get_logger()
 
 
+def _normalize_contexts(
+    contexts: list[str | Enum] | tuple[str | Enum, ...],
+) -> list[str]:
+    """Convert a sequence of any Enum subclass and/or plain strings to a list of strings."""
+    return [c.value if isinstance(c, Enum) else c for c in contexts]
+
+
 @dataclass
 class Fixture:
     """A fixture definition with metadata."""
@@ -50,17 +58,42 @@ class FixtureRegistry:
                 Post(id=1, title="Test", user_id=1),
             ]
         ```
+
+    Fixtures with the same name may be registered for **different** contexts.
+    When multiple contexts are loaded together, their instances are merged:
+
+        ```python
+        @fixtures.register(contexts=[Context.BASE])
+        def users():
+            return [User(id=1, username="admin")]
+
+        @fixtures.register(contexts=[Context.TESTING])
+        def users():
+            return [User(id=2, username="tester")]
+        # load_fixtures_by_context(..., Context.BASE, Context.TESTING)
+        # → loads both User(admin) and User(tester) under the "users" name
+        ```
     """
 
     def __init__(
         self,
-        contexts: list[str | Context] | None = None,
+        contexts: list[str | Enum] | None = None,
     ) -> None:
-        self._fixtures: dict[str, Fixture] = {}
+        self._fixtures: dict[str, list[Fixture]] = {}
         self._default_contexts: list[str] | None = (
-            [c.value if isinstance(c, Context) else c for c in contexts]
+            _normalize_contexts(contexts) if contexts else None
-            if contexts
+        )
-            else None
+
+    def _validate_no_context_overlap(self, name: str, new_contexts: list[str]) -> None:
+        """Raise ``ValueError`` if any existing variant for *name* overlaps."""
+        existing_variants = self._fixtures.get(name, [])
+        new_set = set(new_contexts)
+        for variant in existing_variants:
+            if set(variant.contexts) & new_set:
+                raise ValueError(
+                    f"Fixture '{name}' already exists in the current registry "
+                    f"with overlapping contexts. Use distinct context sets for "
+                    f"each variant of the same fixture name."
                 )
 
     def register(
@@ -69,7 +102,7 @@ class FixtureRegistry:
         *,
         name: str | None = None,
         depends_on: list[str] | None = None,
-        contexts: list[str | Context] | None = None,
+        contexts: list[str | Enum] | None = None,
     ) -> Callable[..., Any]:
         """Register a fixture function.
 
@@ -79,7 +112,8 @@ class FixtureRegistry:
             func: Fixture function returning list of model instances
             name: Fixture name (defaults to function name)
             depends_on: List of fixture names this depends on
-            contexts: List of contexts this fixture belongs to
+            contexts: List of contexts this fixture belongs to.  Both
+                :class:`Context` enum values and plain strings are accepted.
 
         Example:
             ```python
@@ -90,7 +124,6 @@ class FixtureRegistry:
             @fixtures.register(depends_on=["roles"], contexts=[Context.TESTING])
             def test_users():
                 return [User(id=1, username="test", role_id=1)]
-            ```
         """
 
         def decorator(
@@ -98,20 +131,21 @@ class FixtureRegistry:
         ) -> Callable[[], Sequence[DeclarativeBase]]:
             fixture_name = name or cast(Any, fn).__name__
             if contexts is not None:
-                fixture_contexts = [
+                fixture_contexts = _normalize_contexts(contexts)
-                    c.value if isinstance(c, Context) else c for c in contexts
-                ]
             elif self._default_contexts is not None:
                 fixture_contexts = self._default_contexts
             else:
                 fixture_contexts = [Context.BASE.value]
 
-            self._fixtures[fixture_name] = Fixture(
+            self._validate_no_context_overlap(fixture_name, fixture_contexts)
+            self._fixtures.setdefault(fixture_name, []).append(
+                Fixture(
                     name=fixture_name,
                     func=fn,
                     depends_on=depends_on or [],
                     contexts=fixture_contexts,
                 )
+            )
             return fn
 
         if func is not None:
@@ -121,11 +155,14 @@ class FixtureRegistry:
     def include_registry(self, registry: "FixtureRegistry") -> None:
         """Include another `FixtureRegistry` in the same current `FixtureRegistry`.
 
+        Fixtures with the same name are allowed as long as their context sets
+        do not overlap.  Conflicting contexts raise :class:`ValueError`.
+
         Args:
             registry: The `FixtureRegistry` to include
 
         Raises:
-            ValueError: If a fixture name already exists in the current registry
+            ValueError: If a fixture name already exists with overlapping contexts
 
         Example:
             ```python
@@ -139,31 +176,73 @@ class FixtureRegistry:
             registry.include_registry(registry=dev_registry)
             ```
         """
-        for name, fixture in registry._fixtures.items():
+        for name, variants in registry._fixtures.items():
-            if name in self._fixtures:
+            for fixture in variants:
-                raise ValueError(
+                self._validate_no_context_overlap(name, fixture.contexts)
-                    f"Fixture '{name}' already exists in the current registry"
+                self._fixtures.setdefault(name, []).append(fixture)
-                )
-            self._fixtures[name] = fixture
 
     def get(self, name: str) -> Fixture:
-        """Get a fixture by name."""
+        """Get a fixture by name.
+
+        Raises:
+            KeyError: If no fixture with *name* is registered.
+            ValueError: If the fixture has multiple context variants — use
+                :meth:`get_variants` in that case.
+        """
         if name not in self._fixtures:
             raise KeyError(f"Fixture '{name}' not found")
-        return self._fixtures[name]
+        variants = self._fixtures[name]
+        if len(variants) > 1:
+            raise ValueError(
+                f"Fixture '{name}' has {len(variants)} context variants. "
+                f"Use get_variants('{name}') to retrieve them."
+            )
+        return variants[0]
+
+    def get_variants(self, name: str, *contexts: str | Enum) -> list[Fixture]:
+        """Return all registered variants for *name*, optionally filtered by context.
+
+        Args:
+            name: Fixture name.
+            *contexts: If given, only return variants whose context set
+                intersects with these values.  Both :class:`Context` enum
+                values and plain strings are accepted.
+
+        Returns:
+            List of matching :class:`Fixture` objects (may be empty when a
+            context filter is applied and nothing matches).
+
+        Raises:
+            KeyError: If no fixture with *name* is registered.
+        """
+        if name not in self._fixtures:
+            raise KeyError(f"Fixture '{name}' not found")
+        variants = self._fixtures[name]
+        if not contexts:
+            return list(variants)
+        context_values = set(_normalize_contexts(contexts))
+        return [v for v in variants if set(v.contexts) & context_values]
 
     def get_all(self) -> list[Fixture]:
-        """Get all registered fixtures."""
+        """Get all registered fixtures (all variants of all names)."""
-        return list(self._fixtures.values())
+        return [f for variants in self._fixtures.values() for f in variants]
 
-    def get_by_context(self, *contexts: str | Context) -> list[Fixture]:
+    def get_by_context(self, *contexts: str | Enum) -> list[Fixture]:
         """Get fixtures for specific contexts."""
-        context_values = {c.value if isinstance(c, Context) else c for c in contexts}
+        context_values = set(_normalize_contexts(contexts))
-        return [f for f in self._fixtures.values() if set(f.contexts) & context_values]
+        return [
+            f
+            for variants in self._fixtures.values()
+            for f in variants
+            if set(f.contexts) & context_values
+        ]
 
     def resolve_dependencies(self, *names: str) -> list[str]:
         """Resolve fixture dependencies in topological order.
 
+        When a fixture name has multiple context variants, the union of all
+        variants' ``depends_on`` lists is used.
+
         Args:
             *names: Fixture names to resolve
 
@@ -185,9 +264,20 @@ class FixtureRegistry:
                 raise ValueError(f"Circular dependency detected: {name}")
 
             visiting.add(name)
-            fixture = self.get(name)
+            variants = self._fixtures.get(name)
+            if variants is None:
+                raise KeyError(f"Fixture '{name}' not found")
 
-            for dep in fixture.depends_on:
+            # Union of depends_on across all variants, preserving first-seen order.
+            seen_deps: set[str] = set()
+            all_deps: list[str] = []
+            for variant in variants:
+                for dep in variant.depends_on:
+                    if dep not in seen_deps:
+                        all_deps.append(dep)
+                        seen_deps.add(dep)
+
+            for dep in all_deps:
                 visit(dep)
 
             visiting.remove(name)
@@ -199,7 +289,7 @@ class FixtureRegistry:
 
         return resolved
 
-    def resolve_context_dependencies(self, *contexts: str | Context) -> list[str]:
+    def resolve_context_dependencies(self, *contexts: str | Enum) -> list[str]:
         """Resolve all fixtures for contexts with dependencies.
 
         Args:
@@ -209,7 +299,9 @@ class FixtureRegistry:
             List of fixture names in load order
         """
         context_fixtures = self.get_by_context(*contexts)
-        names = [f.name for f in context_fixtures]
+        # Deduplicate names while preserving first-seen order (a name can
+        # appear multiple times if it has variants in different contexts).
+        names = list(dict.fromkeys(f.name for f in context_fixtures))
 
         all_deps: set[str] = set()
         for name in names:

src/fastapi_toolsets/fixtures/utils.py

@@ -1,6 +1,7 @@
 """Fixture loading utilities for database seeding."""
 
 from collections.abc import Callable, Sequence
+from enum import Enum
 from typing import Any
 
 from sqlalchemy.ext.asyncio import AsyncSession
@@ -10,7 +11,7 @@ from ..db import get_transaction
 from ..logger import get_logger
 from ..types import ModelType
 from .enum import LoadStrategy
-from .registry import Context, FixtureRegistry
+from .registry import FixtureRegistry, _normalize_contexts
 
 logger = get_logger()
 
@@ -20,13 +21,35 @@ async def _load_ordered(
     registry: FixtureRegistry,
     ordered_names: list[str],
     strategy: LoadStrategy,
+    contexts: tuple[str, ...] | None = None,
 ) -> dict[str, list[DeclarativeBase]]:
-    """Load fixtures in order."""
+    """Load fixtures in order.
+
+    When *contexts* is provided only variants whose context set intersects with
+    *contexts* are called for each name; their instances are concatenated.
+    When *contexts* is ``None`` all variants of each name are loaded.
+    """
     results: dict[str, list[DeclarativeBase]] = {}
 
     for name in ordered_names:
-        fixture = registry.get(name)
+        variants = (
-        instances = list(fixture.func())
+            registry.get_variants(name, *contexts)
+            if contexts is not None
+            else registry.get_variants(name)
+        )
+
+        # Cross-context dependency fallback: if we're loading by context but
+        # no variant matches (e.g. a "base"-only fixture required by a
+        # "testing" fixture), load all available variants so the dependency
+        # is satisfied.
+        if contexts is not None and not variants:
+            variants = registry.get_variants(name)
+
+        if not variants:
+            results[name] = []
+            continue
+
+        instances = [inst for v in variants for inst in v.func()]
 
         if not instances:
             results[name] = []
@@ -109,6 +132,8 @@ async def load_fixtures(
 ) -> dict[str, list[DeclarativeBase]]:
     """Load specific fixtures by name with dependencies.
 
+    All context variants of each requested fixture are loaded and merged.
+
     Args:
         session: Database session
         registry: Fixture registry
@@ -125,19 +150,27 @@ async def load_fixtures(
 async def load_fixtures_by_context(
     session: AsyncSession,
     registry: FixtureRegistry,
-    *contexts: str | Context,
+    *contexts: str | Enum,
     strategy: LoadStrategy = LoadStrategy.MERGE,
 ) -> dict[str, list[DeclarativeBase]]:
     """Load all fixtures for specific contexts.
 
+    For each fixture name, only the variants whose context set intersects with
+    *contexts* are loaded.  When a name has variants in multiple of the
+    requested contexts, their instances are merged before being inserted.
+
     Args:
         session: Database session
         registry: Fixture registry
-        *contexts: Contexts to load (e.g., Context.BASE, Context.TESTING)
+        *contexts: Contexts to load (e.g., ``Context.BASE``, ``Context.TESTING``,
+            or plain strings for custom contexts)
         strategy: How to handle existing records
 
     Returns:
         Dict mapping fixture names to loaded instances
     """
+    context_strings = tuple(_normalize_contexts(contexts))
     ordered = registry.resolve_context_dependencies(*contexts)
-    return await _load_ordered(session, registry, ordered, strategy)
+    return await _load_ordered(
+        session, registry, ordered, strategy, contexts=context_strings
+    )

tests/test_fixtures.py

@@ -1,6 +1,7 @@
 """Tests for fastapi_toolsets.fixtures module."""
 
 import uuid
+from enum import Enum
 
 import pytest
 from sqlalchemy.ext.asyncio import AsyncSession
@@ -19,6 +20,19 @@ from fastapi_toolsets.fixtures.utils import _get_primary_key
 from .conftest import IntRole, Permission, Role, RoleCrud, User, UserCrud
 
 
+class AppContext(str, Enum):
+    """Example user-defined str+Enum context."""
+
+    STAGING = "staging"
+    DEMO = "demo"
+
+
+class PlainEnumContext(Enum):
+    """Example user-defined plain Enum context (no str mixin)."""
+
+    STAGING = "staging"
+
+
 class TestContext:
     """Tests for Context enum."""
 
@@ -39,6 +53,86 @@ class TestContext:
         assert Context.TESTING.value == "testing"
 
 
+class TestCustomEnumContext:
+    """Custom Enum types are accepted wherever Context/str are expected."""
+
+    def test_cannot_subclass_context_with_members(self):
+        """Python prohibits extending an Enum that already has members."""
+        with pytest.raises(TypeError):
+
+            class MyContext(Context):  # noqa: F841  # ty: ignore[subclass-of-final-class]
+                STAGING = "staging"
+
+    def test_custom_enum_values_interchangeable_with_context(self):
+        """A custom enum with the same .value as a built-in Context member is
+        treated as the same context — fixtures registered under one are found
+        by the other."""
+
+        class AppContextFull(str, Enum):
+            BASE = "base"
+            STAGING = "staging"
+
+        registry = FixtureRegistry()
+
+        @registry.register(contexts=[Context.BASE])
+        def roles():
+            return []
+
+        # AppContextFull.BASE has value "base" — same as Context.BASE
+        fixtures = registry.get_by_context(AppContextFull.BASE)
+        assert len(fixtures) == 1
+
+    def test_custom_enum_registry_default_contexts(self):
+        """FixtureRegistry(contexts=[...]) accepts a custom Enum."""
+        registry = FixtureRegistry(contexts=[AppContext.STAGING])
+
+        @registry.register
+        def data():
+            return []
+
+        fixture = registry.get("data")
+        assert fixture.contexts == ["staging"]
+
+    def test_custom_enum_resolve_context_dependencies(self):
+        """resolve_context_dependencies accepts a custom Enum context."""
+        registry = FixtureRegistry()
+
+        @registry.register(contexts=[AppContext.STAGING])
+        def staging_roles():
+            return []
+
+        order = registry.resolve_context_dependencies(AppContext.STAGING)
+        assert "staging_roles" in order
+
+    @pytest.mark.anyio
+    async def test_custom_enum_e2e(self, db_session: AsyncSession):
+        """End-to-end: register with custom Enum, load with the same Enum."""
+        registry = FixtureRegistry()
+
+        @registry.register(contexts=[AppContext.STAGING])
+        def staging_roles():
+            return [Role(id=uuid.uuid4(), name="staging-admin")]
+
+        result = await load_fixtures_by_context(
+            db_session, registry, AppContext.STAGING
+        )
+        assert len(result["staging_roles"]) == 1
+
+    @pytest.mark.anyio
+    async def test_plain_enum_e2e(self, db_session: AsyncSession):
+        """End-to-end: register with plain Enum, load with the same Enum."""
+        registry = FixtureRegistry()
+
+        @registry.register(contexts=[PlainEnumContext.STAGING])
+        def staging_roles():
+            return [Role(id=uuid.uuid4(), name="plain-staging-admin")]
+
+        result = await load_fixtures_by_context(
+            db_session, registry, PlainEnumContext.STAGING
+        )
+        assert len(result["staging_roles"]) == 1
+
+
 class TestLoadStrategy:
     """Tests for LoadStrategy enum."""
 
@@ -407,6 +501,37 @@ class TestDependencyResolution:
         with pytest.raises(ValueError, match="Circular dependency"):
             registry.resolve_dependencies("a")
 
+    def test_resolve_raises_for_unknown_dependency(self):
+        """KeyError when depends_on references an unregistered fixture."""
+        registry = FixtureRegistry()
+
+        @registry.register(depends_on=["ghost"])
+        def users():
+            return []
+
+        with pytest.raises(KeyError, match="ghost"):
+            registry.resolve_dependencies("users")
+
+    def test_resolve_deduplicates_shared_depends_on_across_variants(self):
+        """A dep shared by two same-name variants appears only once in the order."""
+        registry = FixtureRegistry()
+
+        @registry.register(contexts=[Context.BASE])
+        def roles():
+            return []
+
+        @registry.register(depends_on=["roles"], contexts=[Context.BASE])
+        def items():
+            return []
+
+        @registry.register(depends_on=["roles"], contexts=[Context.TESTING])
+        def items():  # noqa: F811
+            return []
+
+        order = registry.resolve_dependencies("items")
+        assert order.count("roles") == 1
+        assert order.index("roles") < order.index("items")
+
     def test_resolve_context_dependencies(self):
         """Resolve all fixtures for a context with dependencies."""
         registry = FixtureRegistry()
@@ -795,3 +920,28 @@ class TestGetPrimaryKey:
         instance = Permission(subject="post")  # action is None
         pk = _get_primary_key(instance)
         assert pk is None
+
+
+class TestRegistryGetVariants:
+    """Tests for FixtureRegistry.get and get_variants edge cases."""
+
+    def test_get_raises_value_error_for_multi_variant(self):
+        """get() raises ValueError when the fixture has multiple context variants."""
+        registry = FixtureRegistry()
+
+        @registry.register(contexts=[Context.BASE])
+        def items():
+            return []
+
+        @registry.register(contexts=[Context.TESTING])
+        def items():  # noqa: F811
+            return []
+
+        with pytest.raises(ValueError, match="get_variants"):
+            registry.get("items")
+
+    def test_get_variants_raises_key_error_for_unknown(self):
+        """get_variants() raises KeyError for an unregistered name."""
+        registry = FixtureRegistry()
+        with pytest.raises(KeyError, match="not found"):
+            registry.get_variants("no_such_fixture")