WIP trying to handle Maybe declaration

pytest_factoryboy/fixture.py

@@ -210,6 +210,51 @@ def make_declaration_fixturedef(
     related: list[str],
 ) -> Callable[..., Any]:
     """Create the FixtureDef for a factory declaration."""
+    if isinstance(value, factory.Maybe):
+        if value.FACTORY_BUILDER_PHASE != factory.enums.BuilderPhase.ATTRIBUTE_RESOLUTION:
+            raise NotImplementedError("Maybe declarations are not supported with post-generation declarations.")
+
+        if not isinstance(value.decider, factory.SelfAttribute):
+            raise NotImplementedError("Maybe declarations are only supported with SelfAttribute deciders.")
+
+        if value.decider.depth != 0:
+            raise NotImplementedError("Maybe declarations are only supported with SelfAttributes of depth 0.")
+
+        yes_declaration = value.yes
+        if yes_declaration != factory.declarations.SKIP:
+            yes_declaration = make_declaration_fixturedef(
+                attr_name + "__yes_declaration",
+                value=value.yes_declaration,
+                factory_class=factory_class,
+            )
+        no_declaration = value.no
+        if no_declaration != factory.declarations.SKIP:
+            no_declaration = make_declaration_fixturedef(
+                attr_name + "__no_declaration",
+                value=value.no_declaration,
+                factory_class=factory_class,
+            )
+
+        new_maybe = factory.Maybe(
+            decider=value.decider,
+            yes_declaration=yes_declaration,
+            no_declaration=no_declaration,
+        )
+
+        # we want to generate a fixture like
+        # @pytest.fixture
+        # def user__company__decider(user__is_staff):
+        #     return user__is_staff
+        # @pytest.fixture
+        # def user__company__yes_declaration(user__company__decider):
+        #     return ...
+        # @pytest.fixture
+        # def user__company__no_declaration(user__company__decider):
+        #     return None
+        # @pytest.fixture
+        # def user__company(request, user__company__decider, user__company__yes_declaration, user__company__no_declaration):
+        #     declaration = yes_declaration if user__company__decider else no_declaration
+        #     return evaluate(request, request.getfixturevalue(declaration))
     if isinstance(value, (factory.SubFactory, factory.RelatedFactory)):
         subfactory_class = value.get_factory()
         subfactory_deps = get_deps(subfactory_class, factory_class)

tests/maybe/test_subfactory.py

@@ -0,0 +1,46 @@
+from __future__ import annotations
+
+from dataclasses import *
+
+import pytest
+from factory import *
+
+from pytest_factoryboy import register
+
+
+@dataclass
+class Company:
+    name: str
+
+
+@dataclass
+class User:
+    is_staff: bool
+    company: Company | None
+
+
+@register
+class CompanyFactory(Factory):
+    class Meta:
+        model = Company
+
+    name = "foo"
+
+
+@register
+class UserFactory(Factory):
+    class Meta:
+        model = User
+
+    is_staff = False
+    company = Maybe("is_staff", yes_declaration=None, no_declaration=SubFactory(CompanyFactory))
+
+
+@pytest.mark.parametrize("user__is_staff", [False])
+def test_staff_user_has_no_company_by_default(user):
+    assert user.company is None
+
+
+@pytest.mark.parametrize("user__is_staff", [False])
+def test_normal_user_has_company_by_default(user, company):
+    assert user.company is company