latest changes

.gitignore

@@ -4,3 +4,4 @@ out/
 /test_sqlite.py
 /django
 .idea/
+.mypy_cache/

conftest.py

@@ -1,3 +1,3 @@
 pytest_plugins = [
-    'test.data'
+    'test.pytest_plugin'
 ]

django-stubs/apps/__init__.pyi

@@ -0,0 +1,7 @@
+from .config import (
+    AppConfig as AppConfig
+)
+
+from .registry import (
+    apps as apps
+)

django-stubs/apps/config.pyi

@@ -0,0 +1,26 @@
+from typing import Any, Iterator, Type
+
+from django.db.models.base import Model
+
+MODELS_MODULE_NAME: str
+
+class AppConfig:
+    name: str = ...
+    module: Any = ...
+    apps: None = ...
+    label: str = ...
+    verbose_name: str = ...
+    path: str = ...
+    models_module: None = ...
+    models: None = ...
+    def __init__(self, app_name: str, app_module: None) -> None: ...
+    @classmethod
+    def create(cls, entry: str) -> AppConfig: ...
+    def get_model(
+        self, model_name: str, require_ready: bool = ...
+    ) -> Type[Model]: ...
+    def get_models(
+        self, include_auto_created: bool = ..., include_swapped: bool = ...
+    ) -> Iterator[Type[Model]]: ...
+    def import_models(self) -> None: ...
+    def ready(self) -> None: ...

django-stubs/apps/registry.pyi

@@ -0,0 +1,62 @@
+import collections
+from typing import Any, Callable, List, Optional, Tuple, Type, Union, Iterable
+
+from django.apps.config import AppConfig
+from django.db.migrations.state import AppConfigStub
+from django.db.models.base import Model
+
+from .config import AppConfig
+
+
+class Apps:
+    all_models: collections.defaultdict = ...
+    app_configs: collections.OrderedDict = ...
+    stored_app_configs: List[Any] = ...
+    apps_ready: bool = ...
+    loading: bool = ...
+    def __init__(
+        self,
+        installed_apps: Optional[
+            Union[List[AppConfigStub], List[str], Tuple]
+        ] = ...,
+    ) -> None: ...
+    models_ready: bool = ...
+    ready: bool = ...
+    def populate(
+        self, installed_apps: Union[List[AppConfigStub], List[str], Tuple] = ...
+    ) -> None: ...
+    def check_apps_ready(self) -> None: ...
+    def check_models_ready(self) -> None: ...
+    def get_app_configs(self) -> Iterable[AppConfig]: ...
+    def get_app_config(self, app_label: str) -> AppConfig: ...
+    def get_models(
+        self, include_auto_created: bool = ..., include_swapped: bool = ...
+    ) -> List[Type[Model]]: ...
+    def get_model(
+        self,
+        app_label: str,
+        model_name: Optional[str] = ...,
+        require_ready: bool = ...,
+    ) -> Type[Model]: ...
+    def register_model(self, app_label: str, model: Type[Model]) -> None: ...
+    def is_installed(self, app_name: str) -> bool: ...
+    def get_containing_app_config(
+        self, object_name: str
+    ) -> Optional[AppConfig]: ...
+    def get_registered_model(
+        self, app_label: str, model_name: str
+    ) -> Type[Model]: ...
+    def get_swappable_settings_name(self, to_string: str) -> Optional[str]: ...
+    def set_available_apps(self, available: List[str]) -> None: ...
+    def unset_available_apps(self) -> None: ...
+    def set_installed_apps(
+        self, installed: Union[List[str], Tuple[str]]
+    ) -> None: ...
+    def unset_installed_apps(self) -> None: ...
+    def clear_cache(self) -> None: ...
+    def lazy_model_operation(
+        self, function: Callable, *model_keys: Any
+    ) -> None: ...
+    def do_pending_operations(self, model: Type[Model]) -> None: ...
+
+apps: Apps

django-stubs/db/__init__.pyi

@@ -1,2 +1,18 @@
+from typing import Any
+
 from .utils import (ProgrammingError as ProgrammingError,
-                    IntegrityError as IntegrityError)
+                    IntegrityError as IntegrityError,
+                    OperationalError as OperationalError,
+                    DatabaseError as DatabaseError,
+                    DataError as DataError,
+                    NotSupportedError as NotSupportedError)
+
+connections: Any
+router: Any
+
+class DefaultConnectionProxy:
+    def __getattr__(self, item: str) -> Any: ...
+    def __setattr__(self, name: str, value: Any) -> None: ...
+    def __delattr__(self, name: str) -> None: ...
+
+connection: Any

django-stubs/db/models/__init__.pyi

@@ -3,14 +3,21 @@ from .base import Model as Model
 from .fields import (AutoField as AutoField,
                      IntegerField as IntegerField,
                      SmallIntegerField as SmallIntegerField,
+                     BigIntegerField as BigIntegerField,
                      CharField as CharField,
                      Field as Field,
                      SlugField as SlugField,
                      TextField as TextField,
-                     BooleanField as BooleanField)
+                     BooleanField as BooleanField,
+                     FileField as FileField,
+                     DateField as DateField,
+                     DateTimeField as DateTimeField,
+                     IPAddressField as IPAddressField,
+                     GenericIPAddressField as GenericIPAddressField)
 
 from .fields.related import (ForeignKey as ForeignKey,
-                             OneToOneField as OneToOneField)
+                             OneToOneField as OneToOneField,
+                             ManyToManyField as ManyToManyField)
 
 from .deletion import (CASCADE as CASCADE,
                        SET_DEFAULT as SET_DEFAULT,
@@ -24,4 +31,11 @@ from .query_utils import Q as Q
 
 from .lookups import Lookup as Lookup
 
-from .expressions import F as F
+from .expressions import (F as F,
+                          Subquery as Subquery,
+                          Exists as Exists,
+                          OrderBy as OrderBy,
+                          OuterRef as OuterRef)
+
+from .manager import (BaseManager as BaseManager,
+                      Manager as Manager)

django-stubs/db/models/expressions.pyi

@@ -3,6 +3,7 @@ from datetime import datetime, timedelta
 from typing import (Any, Callable, Dict, Iterator, List, Optional, Set, Tuple,
                     Type, Union)
 
+from django.db.models import QuerySet
 from django.db.models.fields import Field
 from django.db.models.lookups import Lookup
 from django.db.models.sql.compiler import SQLCompiler
@@ -180,4 +181,50 @@ class CombinedExpression(SQLiteNumericMixin, Expression):
 
 
 class F(Combinable):
+    name: str
     def __init__(self, name: str): ...
+    def resolve_expression(
+        self,
+        query: Any = ...,
+        allow_joins: bool = ...,
+        reuse: Optional[Set[str]] = ...,
+        summarize: bool = ...,
+        for_save: bool = ...,
+    ) -> Expression: ...
+
+
+class OuterRef(F): ...
+
+class Subquery(Expression):
+    template: str = ...
+    queryset: QuerySet = ...
+    extra: Dict[Any, Any] = ...
+    def __init__(
+        self,
+        queryset: QuerySet,
+        output_field: Optional[Field] = ...,
+        **extra: Any
+    ) -> None: ...
+
+class Exists(Subquery):
+    extra: Dict[Any, Any]
+    template: str = ...
+    negated: bool = ...
+    def __init__(
+        self, *args: Any, negated: bool = ..., **kwargs: Any
+    ) -> None: ...
+    def __invert__(self) -> Exists: ...
+
+class OrderBy(BaseExpression):
+    template: str = ...
+    nulls_first: bool = ...
+    nulls_last: bool = ...
+    descending: bool = ...
+    expression: Expression = ...
+    def __init__(
+        self,
+        expression: Combinable,
+        descending: bool = ...,
+        nulls_first: bool = ...,
+        nulls_last: bool = ...,
+    ) -> None: ...

django-stubs/db/models/fields/__init__.pyi

@@ -1,4 +1,4 @@
-from typing import Any
+from typing import Any, Optional
 
 from django.db.models.query_utils import RegisterLookupMixin
 
@@ -7,6 +7,7 @@ class Field(RegisterLookupMixin):
     def __init__(self,
                  primary_key: bool = False,
                  **kwargs): ...
+
     def __get__(self, instance, owner) -> Any: ...
 
 
@@ -14,8 +15,10 @@ class IntegerField(Field):
     def __get__(self, instance, owner) -> int: ...
 
 
-class SmallIntegerField(IntegerField):
-    pass
+class SmallIntegerField(IntegerField): ...
+
+
+class BigIntegerField(IntegerField): ...
 
 
 class AutoField(Field):
@@ -26,11 +29,11 @@ class CharField(Field):
     def __init__(self,
                  max_length: int,
                  **kwargs): ...
+
     def __get__(self, instance, owner) -> str: ...
 
 
-class SlugField(CharField):
-    pass
+class SlugField(CharField): ...
 
 
 class TextField(Field):
@@ -39,3 +42,29 @@ class TextField(Field):
 
 class BooleanField(Field):
     def __get__(self, instance, owner) -> bool: ...
+
+
+class FileField(Field): ...
+
+
+class IPAddressField(Field): ...
+
+
+class GenericIPAddressField(Field):
+    default_error_messages: Any = ...
+    unpack_ipv4: Any = ...
+    protocol: Any = ...
+
+    def __init__(
+            self,
+            verbose_name: Optional[Any] = ...,
+            name: Optional[Any] = ...,
+            protocol: str = ...,
+            unpack_ipv4: bool = ...,
+            *args: Any,
+            **kwargs: Any
+    ) -> None: ...
+
+class DateField(Field): ...
+
+class DateTimeField(DateField): ...

django-stubs/db/models/fields/related.pyi

@@ -22,3 +22,12 @@ class OneToOneField(Field, Generic[_T]):
                  related_name: str = ...,
                  **kwargs): ...
     def __get__(self, instance, owner) -> _T: ...
+
+
+class ManyToManyField(Field, Generic[_T]):
+    def __init__(self,
+                 to: Union[Type[_T], str],
+                 on_delete: Any,
+                 related_name: str = ...,
+                 **kwargs): ...
+    def __get__(self, instance, owner) -> _T: ...

django-stubs/db/models/manager.pyi

@@ -0,0 +1,140 @@
+from collections import OrderedDict
+from datetime import datetime
+from decimal import Decimal
+from typing import Any, Dict, List, Optional, Tuple, Type, Union, TypeVar, Set, Generic, Iterator
+from unittest.mock import MagicMock
+
+from django.db.models import Q
+from django.db.models.base import Model
+from django.db.models.query import QuerySet, RawQuerySet
+
+_T = TypeVar('_T', bound=Model)
+
+
+class BaseManager:
+    creation_counter: int = ...
+    auto_created: bool = ...
+    use_in_migrations: bool = ...
+    def __new__(cls: Type[BaseManager], *args: Any, **kwargs: Any) -> BaseManager: ...
+    model: Any = ...
+    name: Any = ...
+    def __init__(self) -> None: ...
+    def deconstruct(self) -> Tuple[bool, str, None, Tuple, Dict[str, int]]: ...
+    def check(self, **kwargs: Any) -> List[Any]: ...
+    @classmethod
+    def from_queryset(
+        cls, queryset_class: Any, class_name: Optional[Any] = ...
+    ): ...
+    def contribute_to_class(self, model: Type[Model], name: str) -> None: ...
+    def db_manager(
+        self,
+        using: Optional[str] = ...,
+        hints: Optional[Dict[str, Model]] = ...,
+    ) -> Manager: ...
+    @property
+    def db(self) -> str: ...
+    def get_queryset(self) -> QuerySet: ...
+    def all(self) -> QuerySet: ...
+    def __eq__(self, other: Optional[Any]) -> bool: ...
+    def __hash__(self): ...
+
+class Manager(Generic[_T]):
+    def exists(self) -> bool: ...
+    def explain(
+            self, *, format: Optional[Any] = ..., **options: Any
+    ) -> str: ...
+    def raw(
+            self,
+            raw_query: str,
+            params: Optional[
+                Union[
+                    Dict[str, str],
+                    List[datetime],
+                    List[Decimal],
+                    List[str],
+                    Set[str],
+                    Tuple[int],
+                ]
+            ] = ...,
+            translations: Optional[Dict[str, str]] = ...,
+            using: None = ...,
+    ) -> RawQuerySet: ...
+    def values(self, *fields: Any, **expressions: Any) -> QuerySet: ...
+    def values_list(
+            self, *fields: Any, flat: bool = ..., named: bool = ...
+    ) -> QuerySet: ...
+    def dates(
+            self, field_name: str, kind: str, order: str = ...
+    ) -> QuerySet: ...
+    def datetimes(
+            self, field_name: str, kind: str, order: str = ..., tzinfo: None = ...
+    ) -> QuerySet: ...
+    def none(self) -> QuerySet[_T]: ...
+    def all(self) -> QuerySet[_T]: ...
+    def filter(self, *args: Any, **kwargs: Any) -> QuerySet[_T]: ...
+    def exclude(self, *args: Any, **kwargs: Any) -> QuerySet[_T]: ...
+    def complex_filter(
+            self,
+            filter_obj: Union[
+                Dict[str, datetime], Dict[str, QuerySet], Q, MagicMock
+            ],
+    ) -> QuerySet[_T]: ...
+    def union(self, *other_qs: Any, all: bool = ...) -> QuerySet[_T]: ...
+    def intersection(self, *other_qs: Any) -> QuerySet[_T]: ...
+
+    def difference(self, *other_qs: Any) -> QuerySet[_T]: ...
+
+    def select_for_update(
+            self, nowait: bool = ..., skip_locked: bool = ..., of: Tuple = ...
+    ) -> QuerySet: ...
+
+    def select_related(self, *fields: Any) -> QuerySet[_T]: ...
+
+    def prefetch_related(self, *lookups: Any) -> QuerySet[_T]: ...
+
+    def annotate(self, *args: Any, **kwargs: Any) -> QuerySet[_T]: ...
+
+    def order_by(self, *field_names: Any) -> QuerySet[_T]: ...
+
+    def distinct(self, *field_names: Any) -> QuerySet[_T]: ...
+
+    def extra(
+            self,
+            select: Optional[
+                Union[Dict[str, int], Dict[str, str], OrderedDict]
+            ] = ...,
+            where: Optional[List[str]] = ...,
+            params: Optional[Union[List[int], List[str]]] = ...,
+            tables: Optional[List[str]] = ...,
+            order_by: Optional[Union[List[str], Tuple[str]]] = ...,
+            select_params: Optional[Union[List[int], List[str], Tuple[int]]] = ...,
+    ) -> QuerySet[_T]: ...
+
+    def iterator(self, chunk_size: int = ...) -> Iterator[_T]: ...
+
+    def aggregate(
+            self, *args: Any, **kwargs: Any
+    ) -> Dict[str, Optional[Union[datetime, float]]]: ...
+
+    def count(self) -> int: ...
+
+    def get(
+            self, *args: Any, **kwargs: Any
+    ) -> _T: ...
+
+    def create(self, **kwargs: Any) -> _T: ...
+
+
+class ManagerDescriptor:
+    manager: Manager = ...
+    def __init__(self, manager: Manager) -> None: ...
+    def __get__(
+        self, instance: Optional[Model], cls: Type[Model] = ...
+    ) -> Manager: ...
+
+class EmptyManager(Manager):
+    creation_counter: int
+    name: None
+    model: Optional[Type[Model]] = ...
+    def __init__(self, model: Type[Model]) -> None: ...
+    def get_queryset(self) -> QuerySet: ...

django-stubs/urls/__init__.pyi

@@ -7,3 +7,8 @@ from .conf import (include as include,
 from .resolvers import (ResolverMatch as ResolverMatch,
                         get_ns_resolver as get_ns_resolver,
                         get_resolver as get_resolver)
+
+# noinspection PyUnresolvedReferences
+from .converters import (
+    register_converter as register_converter
+)

django-stubs/utils/baseconv.pyi

@@ -0,0 +1,30 @@
+from typing import Any, Tuple, Union
+
+BASE2_ALPHABET: str
+BASE16_ALPHABET: str
+BASE56_ALPHABET: str
+BASE36_ALPHABET: str
+BASE62_ALPHABET: str
+BASE64_ALPHABET: Any
+
+class BaseConverter:
+    decimal_digits: str = ...
+    sign: str = ...
+    digits: str = ...
+    def __init__(self, digits: str, sign: str = ...) -> None: ...
+    def encode(self, i: int) -> str: ...
+    def decode(self, s: str) -> int: ...
+    def convert(
+        self,
+        number: Union[int, str],
+        from_digits: str,
+        to_digits: str,
+        sign: str,
+    ) -> Tuple[int, str]: ...
+
+base2: Any
+base16: Any
+base36: Any
+base56: Any
+base62: Any
+base64: Any

mypy_django_plugin/helpers.py

@@ -1,15 +1,15 @@
-from typing import Dict, Optional, NamedTuple
+import typing
+from typing import Dict, Optional, NamedTuple, Any
 
-from mypy.semanal import SemanticAnalyzerPass2
-from mypy.types import Type
 from mypy.nodes import SymbolTableNode, Var, Expression
 from mypy.plugin import FunctionContext
-from mypy.types import Instance, UnionType, NoneTyp
+from mypy.types import Type, Instance, UnionType, NoneTyp
 
 MODEL_CLASS_FULLNAME = 'django.db.models.base.Model'
 QUERYSET_CLASS_FULLNAME = 'django.db.models.query.QuerySet'
 FOREIGN_KEY_FULLNAME = 'django.db.models.fields.related.ForeignKey'
 ONETOONE_FIELD_FULLNAME = 'django.db.models.fields.related.OneToOneField'
+DUMMY_SETTINGS_BASE_CLASS = 'django.conf._DjangoConfLazyObject'
 
 
 def create_new_symtable_node(name: str, kind: int, instance: Instance) -> SymbolTableNode:
@@ -26,12 +26,10 @@ Argument = NamedTuple('Argument', fields=[
 
 
 def get_call_signature_or_none(ctx: FunctionContext) -> Optional[Dict[str, Argument]]:
-    arg_names = ctx.context.arg_names
-
     result: Dict[str, Argument] = {}
     positional_args_only = []
     positional_arg_types_only = []
-    for arg, arg_name, arg_type in zip(ctx.args, arg_names, ctx.arg_types):
+    for arg, arg_name, arg_type in zip(ctx.args, ctx.arg_names, ctx.arg_types):
         if arg_name is None:
             positional_args_only.append(arg)
             positional_arg_types_only.append(arg_type)
@@ -65,3 +63,7 @@ def make_required(typ: Type) -> Type:
         return typ
     items = [item for item in typ.items if not isinstance(item, NoneTyp)]
     return UnionType.make_union(items)
+
+
+def get_obj_type_name(typ: typing.Type) -> str:
+    return typ.__module__ + '.' + typ.__qualname__

mypy_django_plugin/main.py

@@ -1,46 +1,79 @@
 import os
-from typing import Callable, Optional
+from typing import Callable, Optional, List
 
+from django.apps.registry import Apps
 from django.conf import Settings
+from mypy import build
+from mypy.build import BuildManager
 from mypy.options import Options
 from mypy.plugin import Plugin, FunctionContext, ClassDefContext
 from mypy.types import Type
 
-from mypy_django_plugin import helpers
+from mypy_django_plugin import helpers, monkeypatch
 from mypy_django_plugin.plugins.objects_queryset import set_objects_queryset_to_model_class
 from mypy_django_plugin.plugins.postgres_fields import determine_type_of_array_field
-from mypy_django_plugin.plugins.related_fields import set_related_name_instance_for_onetoonefield, \
-    set_related_name_manager_for_foreign_key, set_fieldname_attrs_for_related_fields
+from mypy_django_plugin.plugins.related_fields import OneToOneFieldHook, \
+    ForeignKeyHook, set_fieldname_attrs_for_related_fields
 from mypy_django_plugin.plugins.setup_settings import DjangoConfSettingsInitializerHook
 
 
 base_model_classes = {helpers.MODEL_CLASS_FULLNAME}
 
 
-def transform_model_class(ctx: ClassDefContext) -> None:
+class TransformModelClassHook(object):
+    def __init__(self, settings: Settings, apps: Apps):
+        self.settings = settings
+        self.apps = apps
+
+    def __call__(self, ctx: ClassDefContext) -> None:
         base_model_classes.add(ctx.cls.fullname)
 
         set_fieldname_attrs_for_related_fields(ctx)
         set_objects_queryset_to_model_class(ctx)
 
 
+def always_return_none(manager: BuildManager):
+    return None
+
+
+build.read_plugins_snapshot = always_return_none
+
+
 class DjangoPlugin(Plugin):
     def __init__(self,
                  options: Options) -> None:
         super().__init__(options)
         self.django_settings = None
+        self.apps = None
+
+        monkeypatch.replace_apply_function_plugin_method()
 
         django_settings_module = os.environ.get('DJANGO_SETTINGS_MODULE')
         if django_settings_module:
             self.django_settings = Settings(django_settings_module)
+            # import django
+            # django.setup()
+            #
+            # from django.apps import apps
+            # self.apps = apps
+            #
+            # models_modules = []
+            # for app_config in self.apps.app_configs.values():
+            #     models_modules.append(app_config.module.__name__ + '.' + 'models')
+            #
+            # monkeypatch.state_compute_dependencies_to_parse_installed_apps_setting_in_settings_module(django_settings_module,
+            #                                                                                           models_modules)
+            monkeypatch.load_graph_to_add_settings_file_as_a_source_seed(django_settings_module)
 
     def get_function_hook(self, fullname: str
                           ) -> Optional[Callable[[FunctionContext], Type]]:
         if fullname == helpers.FOREIGN_KEY_FULLNAME:
-            return set_related_name_manager_for_foreign_key
+            return ForeignKeyHook(settings=self.django_settings,
+                                  apps=self.apps)
 
         if fullname == helpers.ONETOONE_FIELD_FULLNAME:
-            return set_related_name_instance_for_onetoonefield
+            return OneToOneFieldHook(settings=self.django_settings,
+                                     apps=self.apps)
 
         if fullname == 'django.contrib.postgres.fields.array.ArrayField':
             return determine_type_of_array_field
@@ -49,9 +82,11 @@ class DjangoPlugin(Plugin):
     def get_base_class_hook(self, fullname: str
                             ) -> Optional[Callable[[ClassDefContext], None]]:
         if fullname in base_model_classes:
-            return transform_model_class
-        if fullname == 'django.conf._DjangoConfLazyObject':
+            return TransformModelClassHook(self.django_settings, self.apps)
+
+        if fullname == helpers.DUMMY_SETTINGS_BASE_CLASS:
             return DjangoConfSettingsInitializerHook(settings=self.django_settings)
+
         return None
 
 

mypy_django_plugin/monkeypatch.py

@@ -0,0 +1,112 @@
+from typing import Optional, List, Sequence
+
+from mypy.build import BuildManager, Graph, State
+from mypy.modulefinder import BuildSource
+from mypy.nodes import Expression, Context
+from mypy.plugin import FunctionContext, MethodContext
+from mypy.types import Type, CallableType, Instance
+
+
+def state_compute_dependencies_to_parse_installed_apps_setting_in_settings_module(settings_module: str,
+                                                                                  models_py_modules: List[str]):
+    from mypy.build import State
+
+    old_compute_dependencies = State.compute_dependencies
+
+    def patched_compute_dependencies(self: State):
+        old_compute_dependencies(self)
+        if self.id == settings_module:
+            self.dependencies.extend(models_py_modules)
+
+    State.compute_dependencies = patched_compute_dependencies
+
+
+def load_graph_to_add_settings_file_as_a_source_seed(settings_module: str):
+    from mypy import build
+
+    old_load_graph = build.load_graph
+
+    def patched_load_graph(sources: List[BuildSource], manager: BuildManager,
+                           old_graph: Optional[Graph] = None,
+                           new_modules: Optional[List[State]] = None):
+        if all([source.module != settings_module for source in sources]):
+            sources.append(BuildSource(None, settings_module, None))
+
+        return old_load_graph(sources=sources, manager=manager,
+                              old_graph=old_graph,
+                              new_modules=new_modules)
+
+    build.load_graph = patched_load_graph
+
+
+def replace_apply_function_plugin_method():
+    def apply_function_plugin(self,
+                              arg_types: List[Type],
+                              inferred_ret_type: Type,
+                              arg_names: Optional[Sequence[Optional[str]]],
+                              formal_to_actual: List[List[int]],
+                              args: List[Expression],
+                              num_formals: int,
+                              fullname: str,
+                              object_type: Optional[Type],
+                              context: Context) -> Type:
+        """Use special case logic to infer the return type of a specific named function/method.
+
+        Caller must ensure that a plugin hook exists. There are two different cases:
+
+        - If object_type is None, the caller must ensure that a function hook exists
+          for fullname.
+        - If object_type is not None, the caller must ensure that a method hook exists
+          for fullname.
+
+        Return the inferred return type.
+        """
+        formal_arg_types = [[] for _ in range(num_formals)]  # type: List[List[Type]]
+        formal_arg_exprs = [[] for _ in range(num_formals)]  # type: List[List[Expression]]
+        formal_arg_names = [None for _ in range(num_formals)]  # type: List[Optional[str]]
+        for formal, actuals in enumerate(formal_to_actual):
+            for actual in actuals:
+                formal_arg_types[formal].append(arg_types[actual])
+                formal_arg_exprs[formal].append(args[actual])
+                if arg_names:
+                    formal_arg_names[formal] = arg_names[actual]
+
+        num_passed_positionals = sum([1 if name is None else 0
+                                     for name in formal_arg_names])
+        if arg_names and num_passed_positionals > 0:
+            object_type_info = None
+            if object_type is not None:
+                if isinstance(object_type, CallableType):
+                    # class object, convert to corresponding Instance
+                    object_type = object_type.ret_type
+                if isinstance(object_type, Instance):
+                    # skip TypedDictType and others
+                    object_type_info = object_type.type
+
+            defn_arg_names = self._get_defn_arg_names(fullname, object_type=object_type_info)
+            if defn_arg_names:
+                if num_formals < len(defn_arg_names):
+                    # self/cls argument has been passed implicitly
+                    defn_arg_names = defn_arg_names[1:]
+                formal_arg_names[:num_passed_positionals] = defn_arg_names[:num_passed_positionals]
+
+        if object_type is None:
+            # Apply function plugin
+            callback = self.plugin.get_function_hook(fullname)
+            assert callback is not None  # Assume that caller ensures this
+            return callback(
+                FunctionContext(formal_arg_names, formal_arg_types,
+                                inferred_ret_type, formal_arg_exprs,
+                                context, self.chk))
+        else:
+            # Apply method plugin
+            method_callback = self.plugin.get_method_hook(fullname)
+            assert method_callback is not None  # Assume that caller ensures this
+            return method_callback(
+                MethodContext(object_type, formal_arg_names, formal_arg_types,
+                              inferred_ret_type, formal_arg_exprs,
+                              context, self.chk))
+
+    from mypy.checkexpr import ExpressionChecker
+    ExpressionChecker.apply_function_plugin = apply_function_plugin
+

mypy_django_plugin/plugins/objects_queryset.py

@@ -9,19 +9,28 @@ from mypy_django_plugin import helpers
 
 
 def set_objects_queryset_to_model_class(ctx: ClassDefContext) -> None:
-    if 'objects' in ctx.cls.info.names:
-        return
-    api = cast(SemanticAnalyzerPass2, ctx.api)
+    # search over mro
+    objects_sym = ctx.cls.info.get('objects')
+    if objects_sym is not None:
+        return None
 
-    metaclass_node = ctx.cls.info.names.get('Meta')
-    if metaclass_node is not None:
-        for stmt in metaclass_node.node.defn.defs.body:
+    # only direct Meta class
+    metaclass_sym = ctx.cls.info.names.get('Meta')
+    # skip if abstract
+    if metaclass_sym is not None:
+        for stmt in metaclass_sym.node.defn.defs.body:
             if (isinstance(stmt, AssignmentStmt) and len(stmt.lvalues) == 1
                     and stmt.lvalues[0].name == 'abstract'):
-                is_abstract = api.parse_bool(stmt.rvalue)
+                is_abstract = ctx.api.parse_bool(stmt.rvalue)
                 if is_abstract:
-                    return
+                    return None
 
-    typ = api.named_type_or_none(helpers.QUERYSET_CLASS_FULLNAME, args=[Instance(ctx.cls.info, [])])
-    new_objects_node = helpers.create_new_symtable_node('objects', MDEF, instance=typ)
-    ctx.cls.info.names['objects'] = new_objects_node
+    api = cast(SemanticAnalyzerPass2, ctx.api)
+    typ = api.named_type_or_none(helpers.QUERYSET_CLASS_FULLNAME,
+                                 args=[Instance(ctx.cls.info, [])])
+    if not typ:
+        return None
+
+    ctx.cls.info.names['objects'] = helpers.create_new_symtable_node('objects',
+                                                                     kind=MDEF,
+                                                                     instance=typ)

mypy_django_plugin/plugins/postgres_fields.py

@@ -1,14 +1,11 @@
 from mypy.plugin import FunctionContext
 from mypy.types import Type
 
-from mypy_django_plugin import helpers
-
 
 def determine_type_of_array_field(ctx: FunctionContext) -> Type:
-    signature = helpers.get_call_signature_or_none(ctx)
-    if signature is None:
+    if 'base_field' not in ctx.arg_names:
         return ctx.default_return_type
 
-    _, base_field_arg_type = signature['base_field']
+    base_field_arg_type = ctx.arg_types[ctx.arg_names.index('base_field')][0]
     return ctx.api.named_generic_type(ctx.context.callee.fullname,
                                       args=[base_field_arg_type.type.names['__get__'].type.ret_type])

mypy_django_plugin/plugins/related_fields.py

@@ -1,23 +1,63 @@
-from typing import Optional, cast
+import typing
+from typing import Optional, cast, Tuple, Any
 
+from django.apps.registry import Apps
+from django.conf import Settings
+from django.db import models
 from mypy.checker import TypeChecker
-from mypy.nodes import TypeInfo, SymbolTable, MDEF, AssignmentStmt, MemberExpr
+from mypy.nodes import TypeInfo, SymbolTable, MDEF, AssignmentStmt, StrExpr
 from mypy.plugin import FunctionContext, ClassDefContext
 from mypy.types import Type, CallableType, Instance, AnyType
 
 from mypy_django_plugin import helpers
 
 
-def extract_to_value_type(ctx: FunctionContext) -> Optional[Instance]:
-    signature = helpers.get_call_signature_or_none(ctx)
-    if signature is None or 'to' not in signature:
-        return None
+def get_instance_type_for_class(klass: typing.Type[models.Model],
+                                api: TypeChecker) -> Optional[Instance]:
+    model_qualname = helpers.get_obj_type_name(klass)
+    module_name, _, class_name = model_qualname.rpartition('.')
+    module = api.modules.get(module_name)
+    if not module or class_name not in module.names:
+        return
 
-    arg, arg_type = signature['to']
-    if not isinstance(arg_type, CallableType):
-        return None
+    sym = module.names[class_name]
+    return Instance(sym.node, [])
 
-    return arg_type.ret_type
+
+def extract_to_value_type(ctx: FunctionContext,
+                          apps: Optional[Apps]) -> Tuple[Optional[Instance], bool]:
+    api = cast(TypeChecker, ctx.api)
+
+    if 'to' not in ctx.arg_names:
+        return None, False
+    arg = ctx.args[ctx.arg_names.index('to')][0]
+    arg_type = ctx.arg_types[ctx.arg_names.index('to')][0]
+
+    if isinstance(arg_type, CallableType):
+        return arg_type.ret_type, False
+
+    if apps:
+        if isinstance(arg, StrExpr):
+            arg_value = arg.value
+            if '.' not in arg_value:
+                return None, False
+
+            app_label, modelname = arg_value.lower().split('.')
+            try:
+                model_cls = apps.get_model(app_label, modelname)
+            except LookupError:
+                # no model class found
+                return None, False
+            try:
+                instance = get_instance_type_for_class(model_cls, api=api)
+                if not instance:
+                    return None, False
+                return instance, True
+
+            except AssertionError:
+                pass
+
+    return None, False
 
 
 def extract_related_name_value(ctx: FunctionContext) -> str:
@@ -30,43 +70,56 @@ def add_new_class_member(klass_typeinfo: TypeInfo, name: str, new_member_instanc
                                                                   instance=new_member_instance)
 
 
-def set_related_name_manager_for_foreign_key(ctx: FunctionContext) -> Type:
+class ForeignKeyHook(object):
+    def __init__(self, settings: Settings, apps: Apps):
+        self.settings = settings
+        self.apps = apps
+
+    def __call__(self, ctx: FunctionContext) -> Type:
         api = cast(TypeChecker, ctx.api)
         outer_class_info = api.tscope.classes[-1]
 
-    if 'related_name' not in ctx.context.arg_names:
-        return ctx.default_return_type
-
-    referred_to = extract_to_value_type(ctx)
+        referred_to, is_string_based = extract_to_value_type(ctx, apps=self.apps)
         if not referred_to:
             return ctx.default_return_type
 
+        if 'related_name' in ctx.context.arg_names:
             related_name = extract_related_name_value(ctx)
             queryset_type = api.named_generic_type(helpers.QUERYSET_CLASS_FULLNAME,
                                                    args=[Instance(outer_class_info, [])])
             if isinstance(referred_to, AnyType):
-        # referred_to defined as string, which is unsupported for now
                 return ctx.default_return_type
 
             add_new_class_member(referred_to.type,
                                  related_name, queryset_type)
+        if is_string_based:
+            return referred_to
+
         return ctx.default_return_type
 
 
-def set_related_name_instance_for_onetoonefield(ctx: FunctionContext) -> Type:
+class OneToOneFieldHook(object):
+    def __init__(self, settings: Optional[Settings], apps: Optional[Apps]):
+        self.settings = settings
+        self.apps = apps
+
+    def __call__(self, ctx: FunctionContext) -> Type:
         if 'related_name' not in ctx.context.arg_names:
             return ctx.default_return_type
 
-    referred_to = extract_to_value_type(ctx)
+        referred_to, is_string_based = extract_to_value_type(ctx, apps=self.apps)
         if referred_to is None:
             return ctx.default_return_type
 
+        if 'related_name' in ctx.context.arg_names:
             related_name = extract_related_name_value(ctx)
             outer_class_info = ctx.api.tscope.classes[-1]
-
-    api = cast(TypeChecker, ctx.api)
             add_new_class_member(referred_to.type, related_name,
-                         new_member_instance=api.named_type(outer_class_info.fullname()))
+                                 new_member_instance=Instance(outer_class_info, []))
+
+        if is_string_based:
+            return referred_to
+
         return ctx.default_return_type
 
 

mypy_django_plugin/plugins/setup_settings.py

@@ -1,7 +1,7 @@
-from typing import cast, Any
+from typing import cast
 
 from django.conf import Settings
-from mypy.nodes import MDEF, TypeInfo, SymbolTable
+from mypy.nodes import MDEF
 from mypy.plugin import ClassDefContext
 from mypy.semanal import SemanticAnalyzerPass2
 from mypy.types import Instance, AnyType, TypeOfAny
@@ -9,24 +9,22 @@ from mypy.types import Instance, AnyType, TypeOfAny
 from mypy_django_plugin import helpers
 
 
-def get_obj_type_name(value: Any) -> str:
-    return type(value).__module__ + '.' + type(value).__qualname__
-
-
 class DjangoConfSettingsInitializerHook(object):
     def __init__(self, settings: Settings):
         self.settings = settings
 
     def __call__(self, ctx: ClassDefContext) -> None:
         api = cast(SemanticAnalyzerPass2, ctx.api)
+        if self.settings:
             for name, value in self.settings.__dict__.items():
                 if name.isupper():
                     if value is None:
+                        # TODO: change to Optional[Any] later
                         ctx.cls.info.names[name] = helpers.create_new_symtable_node(name, MDEF,
                                                                                     instance=api.builtin_type('builtins.object'))
                         continue
 
-                type_fullname = get_obj_type_name(value)
+                    type_fullname = helpers.get_obj_type_name(type(value))
                     sym = api.lookup_fully_qualified_or_none(type_fullname)
                     if sym is not None:
                         args = len(sym.node.type_vars) * [AnyType(TypeOfAny.from_omitted_generics)]

pytest.ini

@@ -5,3 +5,4 @@ python_files = test*.py
 addopts =
     --tb=native
     -v
+    -s

test/data.py

@@ -147,6 +147,12 @@ class DjangoDataDrivenTestCase(DataDrivenTestCase):
         self.old_cwd = os.getcwd()
 
         self.tmpdir = tempfile.TemporaryDirectory(prefix='mypy-test-')
+        tmpdir_root = os.path.join(self.tmpdir.name, 'tmp')
+
+        new_files = []
+        for path, contents in self.files:
+            new_files.append((path, contents.replace('<TMP>', tmpdir_root)))
+        self.files = new_files
 
         os.chdir(self.tmpdir.name)
         os.mkdir(test_temp_dir)
@@ -179,7 +185,7 @@ class DjangoDataDrivenTestCase(DataDrivenTestCase):
                 self.clean_up.append((True, d))
             self.clean_up.append((False, path))
 
-        sys.path.insert(0, os.path.join(self.tmpdir.name, 'tmp'))
+        sys.path.insert(0, tmpdir_root)
 
     def teardown(self):
         if hasattr(self, 'old_environ'):

test/helpers.py

@@ -0,0 +1,253 @@
+import inspect
+import os
+import re
+from typing import List, Callable, Optional, Tuple
+
+import pytest  # type: ignore  # no pytest in typeshed
+
+skip = pytest.mark.skip
+
+# AssertStringArraysEqual displays special line alignment helper messages if
+# the first different line has at least this many characters,
+MIN_LINE_LENGTH_FOR_ALIGNMENT = 5
+
+
+class TypecheckAssertionError(AssertionError):
+    def __init__(self, error_message: str, lineno: int):
+        self.error_message = error_message
+        self.lineno = lineno
+
+    def first_line(self):
+        return self.__class__.__name__ + '(message="Invalid output")'
+
+    def __str__(self):
+        return self.error_message
+
+
+def _clean_up(a: List[str]) -> List[str]:
+    """Remove common directory prefix from all strings in a.
+
+    This uses a naive string replace; it seems to work well enough. Also
+    remove trailing carriage returns.
+    """
+    res = []
+    for s in a:
+        prefix = os.sep
+        ss = s
+        for p in prefix, prefix.replace(os.sep, '/'):
+            if p != '/' and p != '//' and p != '\\' and p != '\\\\':
+                ss = ss.replace(p, '')
+        # Ignore spaces at end of line.
+        ss = re.sub(' +$', '', ss)
+        res.append(re.sub('\\r$', '', ss))
+    return res
+
+
+def _num_skipped_prefix_lines(a1: List[str], a2: List[str]) -> int:
+    num_eq = 0
+    while num_eq < min(len(a1), len(a2)) and a1[num_eq] == a2[num_eq]:
+        num_eq += 1
+    return max(0, num_eq - 4)
+
+
+def _num_skipped_suffix_lines(a1: List[str], a2: List[str]) -> int:
+    num_eq = 0
+    while (num_eq < min(len(a1), len(a2))
+           and a1[-num_eq - 1] == a2[-num_eq - 1]):
+        num_eq += 1
+    return max(0, num_eq - 4)
+
+
+def _add_aligned_message(s1: str, s2: str, error_message: str) -> str:
+    """Align s1 and s2 so that the their first difference is highlighted.
+
+    For example, if s1 is 'foobar' and s2 is 'fobar', display the
+    following lines:
+
+      E: foobar
+      A: fobar
+           ^
+
+    If s1 and s2 are long, only display a fragment of the strings around the
+    first difference. If s1 is very short, do nothing.
+    """
+
+    # Seeing what went wrong is trivial even without alignment if the expected
+    # string is very short. In this case do nothing to simplify output.
+    if len(s1) < 4:
+        return error_message
+
+    maxw = 72  # Maximum number of characters shown
+
+    error_message += 'Alignment of first line difference:\n'
+    # sys.stderr.write('Alignment of first line difference:\n')
+
+    trunc = False
+    while s1[:30] == s2[:30]:
+        s1 = s1[10:]
+        s2 = s2[10:]
+        trunc = True
+
+    if trunc:
+        s1 = '...' + s1
+        s2 = '...' + s2
+
+    max_len = max(len(s1), len(s2))
+    extra = ''
+    if max_len > maxw:
+        extra = '...'
+
+    # Write a chunk of both lines, aligned.
+    error_message += '  E: {}{}\n'.format(s1[:maxw], extra)
+    # sys.stderr.write('  E: {}{}\n'.format(s1[:maxw], extra))
+    error_message += '  A: {}{}\n'.format(s2[:maxw], extra)
+    # sys.stderr.write('  A: {}{}\n'.format(s2[:maxw], extra))
+    # Write an indicator character under the different columns.
+    error_message += '     '
+    # sys.stderr.write('     ')
+    for j in range(min(maxw, max(len(s1), len(s2)))):
+        if s1[j:j + 1] != s2[j:j + 1]:
+            error_message += '^'
+            # sys.stderr.write('^')  # Difference
+            break
+        else:
+            error_message += ' '
+            # sys.stderr.write(' ')  # Equal
+    error_message += '\n'
+    return error_message
+    # sys.stderr.write('\n')
+
+
+def assert_string_arrays_equal(expected: List[str], actual: List[str]) -> None:
+    """Assert that two string arrays are equal.
+
+    Display any differences in a human-readable form.
+    """
+
+    actual = _clean_up(actual)
+    error_message = ''
+
+    if actual != expected:
+        num_skip_start = _num_skipped_prefix_lines(expected, actual)
+        num_skip_end = _num_skipped_suffix_lines(expected, actual)
+
+        error_message += 'Expected:\n'
+        # sys.stderr.write('Expected:\n')
+
+        # If omit some lines at the beginning, indicate it by displaying a line
+        # with '...'.
+        if num_skip_start > 0:
+            error_message += '  ...\n'
+            # sys.stderr.write('  ...\n')
+
+        # Keep track of the first different line.
+        first_diff = -1
+
+        # Display only this many first characters of identical lines.
+        width = 75
+
+        for i in range(num_skip_start, len(expected) - num_skip_end):
+            if i >= len(actual) or expected[i] != actual[i]:
+                if first_diff < 0:
+                    first_diff = i
+                error_message += '  {:<45} (diff)'.format(expected[i])
+                # sys.stderr.write('  {:<45} (diff)'.format(expected[i]))
+            else:
+                e = expected[i]
+                error_message += '  ' + e[:width]
+                # sys.stderr.write('  ' + e[:width])
+                if len(e) > width:
+                    error_message += '...'
+                    # sys.stderr.write('...')
+            error_message += '\n'
+            # sys.stderr.write('\n')
+        if num_skip_end > 0:
+            error_message += '  ...\n'
+            # sys.stderr.write('  ...\n')
+
+        error_message += 'Actual:\n'
+        # sys.stderr.write('Actual:\n')
+
+        if num_skip_start > 0:
+            error_message += '  ...\n'
+            # sys.stderr.write('  ...\n')
+
+        for j in range(num_skip_start, len(actual) - num_skip_end):
+            if j >= len(expected) or expected[j] != actual[j]:
+                error_message += '  {:<45} (diff)'.format(actual[j])
+                # sys.stderr.write('  {:<45} (diff)'.format(actual[j]))
+            else:
+                a = actual[j]
+                error_message += '  ' + a[:width]
+                # sys.stderr.write('  ' + a[:width])
+                if len(a) > width:
+                    error_message += '...'
+                    # sys.stderr.write('...')
+            error_message += '\n'
+            # sys.stderr.write('\n')
+        if actual == []:
+            error_message += '  (empty)\n'
+            # sys.stderr.write('  (empty)\n')
+        if num_skip_end > 0:
+            error_message += '  ...\n'
+            # sys.stderr.write('  ...\n')
+
+        error_message += '\n'
+        # sys.stderr.write('\n')
+
+        if first_diff >= 0 and first_diff < len(actual) and (
+                len(expected[first_diff]) >= MIN_LINE_LENGTH_FOR_ALIGNMENT
+                or len(actual[first_diff]) >= MIN_LINE_LENGTH_FOR_ALIGNMENT):
+            # Display message that helps visualize the differences between two
+            # long lines.
+            error_message = _add_aligned_message(expected[first_diff], actual[first_diff],
+                                                 error_message)
+
+        first_failure = expected[first_diff]
+        if first_failure:
+            lineno = int(first_failure.split(' ')[0].strip(':').split(':')[1])
+            raise TypecheckAssertionError(error_message=f'Invalid output: \n{error_message}',
+                                          lineno=lineno)
+
+
+def build_output_line(fname: str, lnum: int, severity: str, message: str, col=None) -> str:
+    if col is None:
+        return f'{fname}:{lnum + 1}: {severity}: {message}'
+    else:
+        return f'{fname}:{lnum + 1}:{col}: {severity}: {message}'
+
+
+def expand_errors(input_lines: List[str], fname: str) -> List[str]:
+    """Transform comments such as '# E: message' or
+    '# E:3: message' in input.
+
+    The result is lines like 'fnam:line: error: message'.
+    """
+    output_lines = []
+    for lnum, line in enumerate(input_lines):
+        # The first in the split things isn't a comment
+        for possible_err_comment in line.split(' # ')[1:]:
+            m = re.search(
+                r'^([ENW]):((?P<col>\d+):)? (?P<message>.*)$',
+                possible_err_comment.strip())
+            if m:
+                if m.group(1) == 'E':
+                    severity = 'error'
+                elif m.group(1) == 'N':
+                    severity = 'note'
+                elif m.group(1) == 'W':
+                    severity = 'warning'
+                col = m.group('col')
+                output_lines.append(build_output_line(fname, lnum, severity,
+                                                      message=m.group("message"),
+                                                      col=col))
+    return output_lines
+
+
+def get_func_first_lnum(attr: Callable[..., None]) -> Optional[Tuple[int, List[str]]]:
+    lines, _ = inspect.getsourcelines(attr)
+    for lnum, line in enumerate(lines):
+        no_space_line = line.strip()
+        if f'def {attr.__name__}' in no_space_line:
+            return lnum, lines[lnum + 1:]
+    raise ValueError(f'No line "def {attr.__name__}" found')

test/pytest_plugin.py

@@ -0,0 +1,299 @@
+import dataclasses
+import inspect
+import os
+import sys
+import tempfile
+import textwrap
+from contextlib import contextmanager
+from pathlib import Path
+from typing import Iterator, Any, Optional, cast, List, Type, Callable, Dict
+
+import pytest
+from _pytest._code.code import ReprFileLocation, ReprEntry, ExceptionInfo
+from decorator import decorate
+from mypy import api as mypy_api
+
+from test import vistir
+from test.helpers import assert_string_arrays_equal, TypecheckAssertionError, expand_errors, get_func_first_lnum
+
+
+def reveal_type(obj: Any) -> None:
+    # noop method, just to get rid of "method is not resolved" errors
+    pass
+
+
+def output(output_lines: str):
+    def decor(func: Callable[..., None]):
+        func.out = output_lines
+
+        def wrapper(*args, **kwargs):
+            return func(*args, **kwargs)
+
+        return decorate(func, wrapper)
+
+    return decor
+
+
+def get_class_that_defined_method(meth) -> Type['MypyTypecheckTestCase']:
+    if inspect.ismethod(meth):
+        for cls in inspect.getmro(meth.__self__.__class__):
+            if cls.__dict__.get(meth.__name__) is meth:
+                return cls
+        meth = meth.__func__  # fallback to __qualname__ parsing
+    if inspect.isfunction(meth):
+        cls = getattr(inspect.getmodule(meth),
+                      meth.__qualname__.split('.<locals>', 1)[0].rsplit('.', 1)[0])
+        if issubclass(cls, MypyTypecheckTestCase):
+            return cls
+    return getattr(meth, '__objclass__', None)  # handle special descriptor objects
+
+
+def file(filename: str, make_parent_packages=False):
+    def decor(func: Callable[..., None]):
+        func.filename = filename
+        func.make_parent_packages = make_parent_packages
+        return func
+
+    return decor
+
+
+def env(**environ):
+    def decor(func: Callable[..., None]):
+        func.env = environ
+        return func
+
+    return decor
+
+
+@dataclasses.dataclass
+class CreateFile:
+    sources: str
+    make_parent_packages: bool = False
+
+
+class MypyTypecheckMeta(type):
+    def __new__(mcs, name, bases, attrs):
+        cls = super().__new__(mcs, name, bases, attrs)
+        cls.files: Dict[str, CreateFile] = {}
+
+        for name, attr in attrs.items():
+            if inspect.isfunction(attr):
+                filename = getattr(attr, 'filename', None)
+                if not filename:
+                    continue
+                make_parent_packages = getattr(attr, 'make_parent_packages', False)
+                sources = textwrap.dedent(''.join(get_func_first_lnum(attr)[1]))
+                if sources.strip() == 'pass':
+                    sources = ''
+                cls.files[filename] = CreateFile(sources, make_parent_packages)
+
+        return cls
+
+
+class MypyTypecheckTestCase(metaclass=MypyTypecheckMeta):
+    files = None
+
+    def ini_file(self) -> str:
+        return """
+[mypy]
+        """
+
+    def _get_ini_file_contents(self) -> Optional[str]:
+        raw_ini_file = self.ini_file()
+        if not raw_ini_file:
+            return raw_ini_file
+        return raw_ini_file.strip() + '\n'
+
+
+class TraceLastReprEntry(ReprEntry):
+    def toterminal(self, tw):
+        self.reprfileloc.toterminal(tw)
+        for line in self.lines:
+            red = line.startswith("E   ")
+            tw.line(line, bold=True, red=red)
+        return
+
+
+def fname_to_module(fpath: Path, root_path: Path) -> Optional[str]:
+    try:
+        relpath = fpath.relative_to(root_path).with_suffix('')
+        return str(relpath).replace(os.sep, '.')
+    except ValueError:
+        return None
+
+
+class MypyTypecheckItem(pytest.Item):
+    root_directory = '/run/testdata'
+
+    def __init__(self,
+                 name: str,
+                 parent: 'MypyTestsCollector',
+                 klass: Type[MypyTypecheckTestCase],
+                 source_code: str,
+                 first_lineno: int,
+                 ini_file_contents: Optional[str] = None,
+                 expected_output_lines: Optional[List[str]] = None,
+                 files: Optional[Dict[str, CreateFile]] = None,
+                 custom_environment: Optional[Dict[str, Any]] = None):
+        super().__init__(name=name, parent=parent)
+        self.klass = klass
+        self.source_code = source_code
+        self.first_lineno = first_lineno
+        self.ini_file_contents = ini_file_contents
+        self.expected_output_lines = expected_output_lines
+        self.files = files
+        self.custom_environment = custom_environment
+
+    @contextmanager
+    def temp_directory(self) -> Path:
+        with tempfile.TemporaryDirectory(prefix='mypy-pytest-',
+                                         dir=self.root_directory) as tmpdir_name:
+            yield Path(self.root_directory) / tmpdir_name
+
+    def runtest(self):
+        with self.temp_directory() as tmpdir_path:
+            if not self.source_code:
+                return
+
+            if self.ini_file_contents:
+                mypy_ini_fpath = tmpdir_path / 'mypy.ini'
+                mypy_ini_fpath.write_text(self.ini_file_contents)
+
+            test_specific_modules = []
+            for fname, create_file in self.files.items():
+                fpath = tmpdir_path / fname
+                if create_file.make_parent_packages:
+                    fpath.parent.mkdir(parents=True, exist_ok=True)
+                    for parent in fpath.parents:
+                        try:
+                            parent.relative_to(tmpdir_path)
+                            if parent != tmpdir_path:
+                                parent_init_file = parent / '__init__.py'
+                                parent_init_file.write_text('')
+                                test_specific_modules.append(fname_to_module(parent,
+                                                                             root_path=tmpdir_path))
+                        except ValueError:
+                            break
+
+                fpath.write_text(create_file.sources)
+                test_specific_modules.append(fname_to_module(fpath,
+                                                             root_path=tmpdir_path))
+
+            with vistir.temp_environ(), vistir.temp_path():
+                for key, val in (self.custom_environment or {}).items():
+                    os.environ[key] = val
+                sys.path.insert(0, str(tmpdir_path))
+
+                mypy_cmd_options = self.prepare_mypy_cmd_options(config_file_path=mypy_ini_fpath)
+                main_fpath = tmpdir_path / 'main.py'
+                main_fpath.write_text(self.source_code)
+                mypy_cmd_options.append(str(main_fpath))
+
+                stdout, _, _ = mypy_api.run(mypy_cmd_options)
+                output_lines = []
+                for line in stdout.splitlines():
+                    if ':' not in line:
+                        continue
+                    out_fpath, res_line = line.split(':', 1)
+                    line = os.path.relpath(out_fpath, start=tmpdir_path) + ':' + res_line
+                    output_lines.append(line.strip().replace('.py', ''))
+
+                for module in test_specific_modules:
+                    if module in sys.modules:
+                        del sys.modules[module]
+                raise ValueError
+                assert_string_arrays_equal(expected=self.expected_output_lines,
+                                           actual=output_lines)
+
+    def prepare_mypy_cmd_options(self, config_file_path: Path) -> List[str]:
+        mypy_cmd_options = [
+            '--show-traceback',
+            '--no-silence-site-packages'
+        ]
+        python_version = '.'.join([str(part) for part in sys.version_info[:2]])
+        mypy_cmd_options.append(f'--python-version={python_version}')
+        if self.ini_file_contents:
+            mypy_cmd_options.append(f'--config-file={config_file_path}')
+        return mypy_cmd_options
+
+    def repr_failure(self, excinfo: ExceptionInfo) -> str:
+        if excinfo.errisinstance(SystemExit):
+            # We assume that before doing exit() (which raises SystemExit) we've printed
+            # enough context about what happened so that a stack trace is not useful.
+            # In particular, uncaught exceptions during semantic analysis or type checking
+            # call exit() and they already print out a stack trace.
+            return excinfo.exconly(tryshort=True)
+        elif excinfo.errisinstance(TypecheckAssertionError):
+            # with traceback removed
+            exception_repr = excinfo.getrepr(style='short')
+            exception_repr.reprcrash.message = ''
+            repr_file_location = ReprFileLocation(path=inspect.getfile(self.klass),
+                                                  lineno=self.first_lineno + excinfo.value.lineno,
+                                                  message='')
+            repr_tb_entry = TraceLastReprEntry(filelocrepr=repr_file_location,
+                                               lines=exception_repr.reprtraceback.reprentries[-1].lines[1:],
+                                               style='short',
+                                               reprlocals=None,
+                                               reprfuncargs=None)
+            exception_repr.reprtraceback.reprentries = [repr_tb_entry]
+            return exception_repr
+        else:
+            return super().repr_failure(excinfo, style='short')
+
+    def reportinfo(self):
+        return self.fspath, None, get_class_qualname(self.klass) + '::' + self.name
+
+
+def get_class_qualname(klass: type) -> str:
+    return klass.__module__ + '.' + klass.__name__
+
+
+def extract_test_output(attr: Callable[..., None]) -> List[str]:
+    out_data: str = getattr(attr, 'out', None)
+    out_lines = []
+    if out_data:
+        for line in out_data.split('\n'):
+            line = line.strip()
+            out_lines.append(line)
+    return out_lines
+
+
+class MypyTestsCollector(pytest.Class):
+    def get_ini_file_contents(self, contents: str) -> str:
+        return contents.strip() + '\n'
+
+    def collect(self) -> Iterator[pytest.Item]:
+        current_testcase = cast(MypyTypecheckTestCase, self.obj())
+        ini_file_contents = self.get_ini_file_contents(current_testcase.ini_file())
+        for attr_name in dir(current_testcase):
+            if attr_name.startswith('_test_'):
+                attr = getattr(self.obj, attr_name)
+                if inspect.isfunction(attr):
+                    first_line_lnum, source_lines = get_func_first_lnum(attr)
+                    func_first_line_in_file = inspect.getsourcelines(attr)[1] + first_line_lnum
+
+                    output_from_decorator = extract_test_output(attr)
+                    output_from_comments = expand_errors(source_lines, 'main')
+                    custom_env = getattr(attr, 'env', None)
+                    main_source_code = textwrap.dedent(''.join(source_lines))
+                    yield MypyTypecheckItem(name=attr_name,
+                                            parent=self,
+                                            klass=current_testcase.__class__,
+                                            source_code=main_source_code,
+                                            first_lineno=func_first_line_in_file,
+                                            ini_file_contents=ini_file_contents,
+                                            expected_output_lines=output_from_comments
+                                                                  + output_from_decorator,
+                                            files=current_testcase.__class__.files,
+                                            custom_environment=custom_env)
+
+
+def pytest_pycollect_makeitem(collector: Any, name: str, obj: Any) -> Optional[MypyTestsCollector]:
+    # Only classes derived from DataSuite contain test cases, not the DataSuite class itself
+    if (isinstance(obj, type)
+            and issubclass(obj, MypyTypecheckTestCase)
+            and obj is not MypyTypecheckTestCase):
+        # Non-None result means this obj is a test case.
+        # The collect method of the returned DataSuiteCollector instance will be called later,
+        # with self.obj being obj.
+        return MypyTestsCollector(name, parent=collector)

test/pytest_tests/base.py

@@ -0,0 +1,9 @@
+from test.pytest_plugin import MypyTypecheckTestCase
+
+
+class BaseDjangoPluginTestCase(MypyTypecheckTestCase):
+    def ini_file(self):
+        return """
+[mypy]
+plugins = mypy_django_plugin.main
+        """

test/pytest_tests/test_model_fields.py

@@ -0,0 +1,21 @@
+from test.pytest_plugin import reveal_type
+from test.pytest_tests.base import BaseDjangoPluginTestCase
+
+
+class TestBasicModelFields(BaseDjangoPluginTestCase):
+    def test_model_field_classes_present_as_primitives(self):
+        from django.db import models
+
+        class User(models.Model):
+            id = models.AutoField(primary_key=True)
+            small_int = models.SmallIntegerField()
+            name = models.CharField(max_length=255)
+            slug = models.SlugField(max_length=255)
+            text = models.TextField()
+
+        user = User()
+        reveal_type(user.id)  # E: Revealed type is 'builtins.int'
+        reveal_type(user.small_int)  # E: Revealed type is 'builtins.int'
+        reveal_type(user.name)  # E: Revealed type is 'builtins.str'
+        reveal_type(user.slug)  # E: Revealed type is 'builtins.str'
+        reveal_type(user.text)  # E: Revealed type is 'builtins.str'

test/pytest_tests/test_model_relations.py

@@ -1,16 +1,9 @@
-from test.pytest_plugin import MypyTypecheckTestCase, reveal_type
+from test.pytest_plugin import reveal_type
+from test.pytest_tests.base import BaseDjangoPluginTestCase
 
 
-class BaseDjangoPluginTestCase(MypyTypecheckTestCase):
-    def ini_file(self):
-        return """
-[mypy]
-plugins = mypy_django_plugin.main
-        """
-
-
-class MyTestCase(BaseDjangoPluginTestCase):
-    def check_foreign_key_field(self):
+class TestForeignKey(BaseDjangoPluginTestCase):
+    def test_foreign_key_field(self):
         from django.db import models
 
         class Publisher(models.Model):
@@ -26,7 +19,7 @@ class MyTestCase(BaseDjangoPluginTestCase):
         publisher = Publisher()
         reveal_type(publisher.books)  # E: Revealed type is 'django.db.models.query.QuerySet[main.Book]'
 
-    def check_every_foreign_key_creates_field_name_with_appended_id(self):
+    def test_every_foreign_key_creates_field_name_with_appended_id(self):
         from django.db import models
 
         class Publisher(models.Model):
@@ -39,7 +32,7 @@ class MyTestCase(BaseDjangoPluginTestCase):
         book = Book()
         reveal_type(book.publisher_id)  # E: Revealed type is 'builtins.int'
 
-    def check_foreign_key_different_order_of_params(self):
+    def test_foreign_key_different_order_of_params(self):
         from django.db import models
 
         class Publisher(models.Model):
@@ -54,3 +47,43 @@ class MyTestCase(BaseDjangoPluginTestCase):
 
         publisher = Publisher()
         reveal_type(publisher.books)  # E: Revealed type is 'django.db.models.query.QuerySet[main.Book]'
+
+
+class TestOneToOneField(BaseDjangoPluginTestCase):
+    def test_onetoone_field(self):
+        from django.db import models
+
+        class User(models.Model):
+            pass
+
+        class Profile(models.Model):
+            user = models.OneToOneField(to=User, on_delete=models.CASCADE, related_name='profile')
+
+        profile = Profile()
+        reveal_type(profile.user)  # E: Revealed type is 'main.User*'
+
+        user = User()
+        reveal_type(user.profile)  # E: Revealed type is 'main.Profile'
+
+    def test_onetoone_field_with_underscore_id(self):
+        from django.db import models
+
+        class User(models.Model):
+            pass
+
+        class Profile(models.Model):
+            user = models.OneToOneField(to=User, on_delete=models.CASCADE, related_name='profile')
+
+        profile = Profile()
+        reveal_type(profile.user_id)  # E: Revealed type is 'builtins.int'
+
+    def test_parameter_to_keyword_may_be_absent(self):
+        from django.db import models
+
+        class User(models.Model):
+            pass
+
+        class Profile(models.Model):
+            user = models.OneToOneField(User, on_delete=models.CASCADE, related_name='profile')
+
+        reveal_type(User().profile)  # E: Revealed type is 'main.Profile'

test/pytest_tests/test_objects_queryset.py

@@ -0,0 +1,28 @@
+from test.pytest_plugin import reveal_type, output
+from test.pytest_tests.base import BaseDjangoPluginTestCase
+
+
+class TestObjectsQueryset(BaseDjangoPluginTestCase):
+    def test_every_model_has_objects_queryset_available(self):
+        from django.db import models
+
+        class User(models.Model):
+            pass
+
+        reveal_type(User.objects)  # E: Revealed type is 'django.db.models.query.QuerySet[main.User]'
+
+    @output("""
+main:10: error: Revealed type is 'Any'
+main:10: error: "Type[ModelMixin]" has no attribute "objects"
+    """)
+    def test_objects_get_returns_model_instance(self):
+        from django.db import models
+
+        class ModelMixin(models.Model):
+            class Meta:
+                abstract = True
+
+        class User(ModelMixin):
+            pass
+
+        reveal_type(User.objects.get())  # E: Revealed type is 'main.User*'

test/pytest_tests/test_parse_settings.py

@@ -0,0 +1,37 @@
+from test.pytest_plugin import reveal_type, file, env
+from test.pytest_tests.base import BaseDjangoPluginTestCase
+
+
+class TestParseSettingsFromFile(BaseDjangoPluginTestCase):
+    @env(DJANGO_SETTINGS_MODULE='mysettings')
+    def test_case(self):
+        from django.conf import settings
+
+        reveal_type(settings.ROOT_DIR)  # E: Revealed type is 'builtins.str'
+        reveal_type(settings.OBJ)  # E: Revealed type is 'django.utils.functional.LazyObject'
+        reveal_type(settings.NUMBERS)  # E: Revealed type is 'builtins.list[Any]'
+        reveal_type(settings.DICT)  # E: Revealed type is 'builtins.dict[Any, Any]'
+
+    @file('mysettings.py')
+    def mysettings_py_file(self):
+        SECRET_KEY = 112233
+        ROOT_DIR = '/etc'
+        NUMBERS = ['one', 'two']
+        DICT = {}  # type: ignore
+
+        from django.utils.functional import LazyObject
+
+        OBJ = LazyObject()
+
+
+class TestSettingInitializableToNone(BaseDjangoPluginTestCase):
+    @env(DJANGO_SETTINGS_MODULE='mysettings')
+    def test_case(self):
+        from django.conf import settings
+
+        reveal_type(settings.NONE_SETTING)  # E: Revealed type is 'builtins.object'
+
+    @file('mysettings.py')
+    def mysettings_py_file(self):
+        SECRET_KEY = 112233
+        NONE_SETTING = None

test/pytest_tests/test_postgres_fields.py

@@ -0,0 +1,27 @@
+from test.pytest_plugin import reveal_type
+from test.pytest_tests.base import BaseDjangoPluginTestCase
+
+
+class TestArrayField(BaseDjangoPluginTestCase):
+    def test_descriptor_access(self):
+        from django.db import models
+        from django.contrib.postgres.fields import ArrayField
+
+        class User(models.Model):
+            array = ArrayField(base_field=models.Field())
+
+        user = User()
+        reveal_type(user.array)  # E: Revealed type is 'builtins.list[Any]'
+
+    def test_base_field_parsed_into_generic_attribute(self):
+        from django.db import models
+        from django.contrib.postgres.fields import ArrayField
+
+        class User(models.Model):
+            members = ArrayField(base_field=models.IntegerField())
+            members_as_text = ArrayField(base_field=models.CharField(max_length=255))
+
+        user = User()
+        reveal_type(user.members)  # E: Revealed type is 'builtins.list[builtins.int*]'
+        reveal_type(user.members_as_text)  # E: Revealed type is 'builtins.list[builtins.str*]'
+

test/pytest_tests/test_to_attr_as_string.py

@@ -0,0 +1,74 @@
+from test.pytest_plugin import file, reveal_type, env
+from test.pytest_tests.base import BaseDjangoPluginTestCase
+
+
+class TestForeignKey(BaseDjangoPluginTestCase):
+    @env(DJANGO_SETTINGS_MODULE='mysettings')
+    def _test_to_parameter_could_be_specified_as_string(self):
+        from apps.myapp.models import Publisher
+
+        publisher = Publisher()
+        reveal_type(publisher.books)  # E: Revealed type is 'django.db.models.query.QuerySet[apps.myapp2.models.Book]'
+
+    # @env(DJANGO_SETTINGS_MODULE='mysettings')
+    # def _test_creates_underscore_id_attr(self):
+    #     from apps.myapp2.models import Book
+    #
+    #     book = Book()
+    #     reveal_type(book.publisher)  # E: Revealed type is 'apps.myapp.models.Publisher'
+    #     reveal_type(book.publisher_id)  # E: Revealed type is 'builtins.int'
+
+    @file('mysettings.py')
+    def mysettings(self):
+        SECRET_KEY = '112233'
+        ROOT_DIR = '<TMP>'
+        APPS_DIR = '<TMP>/apps'
+
+        INSTALLED_APPS = ('apps.myapp', 'apps.myapp2')
+
+    @file('apps/myapp/models.py', make_parent_packages=True)
+    def apps_myapp_models(self):
+        from django.db import models
+
+        class Publisher(models.Model):
+            pass
+
+    @file('apps/myapp2/models.py', make_parent_packages=True)
+    def apps_myapp2_models(self):
+        from django.db import models
+
+        class Book(models.Model):
+            publisher = models.ForeignKey(to='myapp.Publisher', on_delete=models.CASCADE,
+                                          related_name='books')
+
+
+class TestOneToOneField(BaseDjangoPluginTestCase):
+    @env(DJANGO_SETTINGS_MODULE='mysettings')
+    def test_to_parameter_could_be_specified_as_string(self):
+        from apps.myapp.models import User
+
+        user = User()
+        reveal_type(user.profile)  # E: Revealed type is 'apps.myapp2.models.Profile'
+
+    @file('mysettings.py')
+    def mysettings(self):
+        SECRET_KEY = '112233'
+        ROOT_DIR = '<TMP>'
+        APPS_DIR = '<TMP>/apps'
+
+        INSTALLED_APPS = ('apps.myapp', 'apps.myapp2')
+
+    @file('apps/myapp/models.py', make_parent_packages=True)
+    def apps_myapp_models(self):
+        from django.db import models
+
+        class User(models.Model):
+            pass
+
+    @file('apps/myapp2/models.py', make_parent_packages=True)
+    def apps_myapp2_models(self):
+        from django.db import models
+
+        class Profile(models.Model):
+            user = models.OneToOneField(to='myapp.User', on_delete=models.CASCADE,
+                                        related_name='profile')

test/testdjango.py

@@ -14,11 +14,14 @@ MYPY_INI_PATH = ROOT_DIR / 'test' / 'plugins.ini'
 
 class DjangoTestSuite(DataSuite):
     files = [
-        'check-objects-queryset.test',
-        'check-model-fields.test',
-        'check-postgres-fields.test',
-        'check-model-relations.test',
-        'check-parse-settings.test'
+        # 'check-objects-queryset.test',
+        # 'check-model-fields.test',
+        # 'check-postgres-fields.test',
+        # 'check-model-relations.test',
+        # 'check-parse-settings.test',
+        # 'check-to-attr-as-string-one-to-one-field.test',
+        'check-to-attr-as-string-foreign-key.test',
+        # 'check-foreign-key-as-string-creates-underscore-id-attr.test'
     ]
     data_prefix = str(TEST_DATA_DIR)
 

test/vistir.py

@@ -0,0 +1,43 @@
+# Borrowed from Pew.
+# See https://github.com/berdario/pew/blob/master/pew/_utils.py#L82
+import os
+import sys
+from pathlib import Path
+
+from decorator import contextmanager
+
+
+@contextmanager
+def temp_environ():
+    """Allow the ability to set os.environ temporarily"""
+    environ = dict(os.environ)
+    try:
+        yield
+    finally:
+        os.environ.clear()
+        os.environ.update(environ)
+
+
+@contextmanager
+def temp_path():
+    """A context manager which allows the ability to set sys.path temporarily"""
+    path = [p for p in sys.path]
+    try:
+        yield
+    finally:
+        sys.path = [p for p in path]
+
+
+@contextmanager
+def cd(path):
+    """Context manager to temporarily change working directories"""
+    if not path:
+        return
+    prev_cwd = Path.cwd().as_posix()
+    if isinstance(path, Path):
+        path = path.as_posix()
+    os.chdir(str(path))
+    try:
+        yield
+    finally:
+        os.chdir(prev_cwd)