feat: strict typing (#70)

* feat: add mypy, update tooling

* feat: add type hints to core lib (#71)

---------

Co-authored-by: Tushar <[email protected]>
Co-authored-by: Zach Aysan <[email protected]>

Author: 3 people

.github/workflows/pytest.yml

@@ -1,12 +1,12 @@
-name: Formatting and Tests
+name: Linting and Tests
 
 on:
   - pull_request
 
 jobs:
   test:
     runs-on: ubuntu-latest
-    name: Pytest and Black formatting
+    name: Linting and Tests
 
     strategy:
       max-parallel: 4
@@ -28,13 +28,16 @@ jobs:
         run: |
           python -m pip install --upgrade pip
           pip install poetry
-          poetry install
+          poetry install --with dev
 
       - name: Check Formatting
         run: |
           poetry run black --check .
           poetry run flake8 .
           poetry run isort --check .
 
+      - name: Check Typing
+        run: poetry run mypy --strict .
+
       - name: Run Tests
         run: poetry run pytest

.pre-commit-config.yaml

@@ -1,17 +1,25 @@
 repos:
-  - repo: https://github.com/asottile/seed-isort-config
-    rev: v1.9.3
+  - repo: https://github.com/pre-commit/mirrors-mypy
+    rev: v1.5.1
     hooks:
-      - id: seed-isort-config
-  - repo: https://github.com/pre-commit/mirrors-isort
-    rev: v4.3.21
+      - id: mypy
+        args: [--strict]
+        additional_dependencies:
+          [pydantic, pytest, pytest_mock, types-requests, flagsmith-flag-engine, responses, types-pytz, sseclient-py]
+  - repo: https://github.com/PyCQA/isort
+    rev: 5.12.0
     hooks:
       - id: isort
   - repo: https://github.com/psf/black
-    rev: 23.3.0
+    rev: 23.7.0
     hooks:
       - id: black
         language_version: python3
+  - repo: https://github.com/pycqa/flake8
+    rev: 6.1.0
+    hooks:
+      - id: flake8
+        name: flake8
   - repo: https://github.com/pre-commit/pre-commit-hooks
     rev: v4.4.0
     hooks:

flagsmith/__init__.py

@@ -1 +1,3 @@
-from .flagsmith import Flagsmith  # noqa
+from .flagsmith import Flagsmith
+
+__all__ = ("Flagsmith",)

flagsmith/analytics.py

@@ -1,12 +1,13 @@
 import json
+import typing
 from datetime import datetime
 
-from requests_futures.sessions import FuturesSession
+from requests_futures.sessions import FuturesSession  # type: ignore
 
-ANALYTICS_ENDPOINT = "analytics/flags/"
+ANALYTICS_ENDPOINT: typing.Final[str] = "analytics/flags/"
 
 # Used to control how often we send data(in seconds)
-ANALYTICS_TIMER = 10
+ANALYTICS_TIMER: typing.Final[int] = 10
 
 session = FuturesSession(max_workers=4)
 
@@ -17,7 +18,9 @@ class AnalyticsProcessor:
     the Flagsmith SDK. Docs: https://docs.flagsmith.com/advanced-use/flag-analytics.
     """
 
-    def __init__(self, environment_key: str, base_api_url: str, timeout: int = 3):
+    def __init__(
+        self, environment_key: str, base_api_url: str, timeout: typing.Optional[int] = 3
+    ):
         """
         Initialise the AnalyticsProcessor to handle sending analytics on flag usage to
         the Flagsmith API.
@@ -30,10 +33,10 @@ def __init__(self, environment_key: str, base_api_url: str, timeout: int = 3):
         self.analytics_endpoint = base_api_url + ANALYTICS_ENDPOINT
         self.environment_key = environment_key
         self._last_flushed = datetime.now()
-        self.analytics_data = {}
-        self.timeout = timeout
+        self.analytics_data: typing.MutableMapping[str, typing.Any] = {}
+        self.timeout = timeout or 3
 
-    def flush(self):
+    def flush(self) -> None:
         """
         Sends all the collected data to the api asynchronously and resets the timer
         """
@@ -53,7 +56,7 @@ def flush(self):
         self.analytics_data.clear()
         self._last_flushed = datetime.now()
 
-    def track_feature(self, feature_name: str):
+    def track_feature(self, feature_name: str) -> None:
         self.analytics_data[feature_name] = self.analytics_data.get(feature_name, 0) + 1
         if (datetime.now() - self._last_flushed).seconds > ANALYTICS_TIMER:
             self.flush()

flagsmith/flagsmith.py

@@ -20,13 +20,23 @@
 from flagsmith.offline_handlers import BaseOfflineHandler
 from flagsmith.polling_manager import EnvironmentDataPollingManager
 from flagsmith.streaming_manager import EventStreamManager, StreamEvent
-from flagsmith.utils.identities import generate_identities_data
+from flagsmith.utils.identities import Identity, generate_identities_data
 
 logger = logging.getLogger(__name__)
 
 DEFAULT_API_URL = "https://edge.api.flagsmith.com/api/v1/"
 DEFAULT_REALTIME_API_URL = "https://realtime.flagsmith.com/"
 
+JsonType = typing.Union[
+    None,
+    int,
+    str,
+    bool,
+    typing.List["JsonType"],
+    typing.List[typing.Mapping[str, "JsonType"]],
+    typing.Dict[str, "JsonType"],
+]
+
 
 class Flagsmith:
     """A Flagsmith client.
@@ -45,19 +55,21 @@ class Flagsmith:
 
     def __init__(
         self,
-        environment_key: str = None,
-        api_url: str = None,
+        environment_key: typing.Optional[str] = None,
+        api_url: typing.Optional[str] = None,
         realtime_api_url: typing.Optional[str] = None,
-        custom_headers: typing.Dict[str, typing.Any] = None,
-        request_timeout_seconds: int = None,
+        custom_headers: typing.Optional[typing.Dict[str, typing.Any]] = None,
+        request_timeout_seconds: typing.Optional[int] = None,
         enable_local_evaluation: bool = False,
         environment_refresh_interval_seconds: typing.Union[int, float] = 60,
-        retries: Retry = None,
+        retries: typing.Optional[Retry] = None,
         enable_analytics: bool = False,
-        default_flag_handler: typing.Callable[[str], DefaultFlag] = None,
-        proxies: typing.Dict[str, str] = None,
+        default_flag_handler: typing.Optional[
+            typing.Callable[[str], DefaultFlag]
+        ] = None,
+        proxies: typing.Optional[typing.Dict[str, str]] = None,
         offline_mode: bool = False,
-        offline_handler: BaseOfflineHandler = None,
+        offline_handler: typing.Optional[BaseOfflineHandler] = None,
         enable_realtime_updates: bool = False,
     ):
         """
@@ -94,8 +106,8 @@ def __init__(
         self.offline_handler = offline_handler
         self.default_flag_handler = default_flag_handler
         self.enable_realtime_updates = enable_realtime_updates
-        self._analytics_processor = None
-        self._environment = None
+        self._analytics_processor: typing.Optional[AnalyticsProcessor] = None
+        self._environment: typing.Optional[EnvironmentModel] = None
         self._identity_overrides_by_identifier: typing.Dict[str, IdentityModel] = {}
 
         # argument validation
@@ -159,6 +171,9 @@ def __init__(
     def _initialise_local_evaluation(self) -> None:
         if self.enable_realtime_updates:
             self.update_environment()
+            if not self._environment:
+                raise ValueError("Unable to get environment from API key")
+
             stream_url = f"{self.realtime_api_url}sse/environments/{self._environment.api_key}/stream"
 
             self.event_stream_thread = EventStreamManager(
@@ -196,6 +211,10 @@ def handle_stream_event(self, event: StreamEvent) -> None:
         if stream_updated_at.tzinfo is None:
             stream_updated_at = pytz.utc.localize(stream_updated_at)
 
+        if not self._environment:
+            raise ValueError(
+                "Unable to access environment. Environment should not be null"
+            )
         environment_updated_at = self._environment.updated_at
         if environment_updated_at.tzinfo is None:
             environment_updated_at = pytz.utc.localize(environment_updated_at)
@@ -214,7 +233,9 @@ def get_environment_flags(self) -> Flags:
         return self._get_environment_flags_from_api()
 
     def get_identity_flags(
-        self, identifier: str, traits: typing.Dict[str, typing.Any] = None
+        self,
+        identifier: str,
+        traits: typing.Optional[typing.Mapping[str, TraitValue]] = None,
     ) -> Flags:
         """
         Get all the flags for the current environment for a given identity. Will also
@@ -233,7 +254,9 @@ def get_identity_flags(
         return self._get_identity_flags_from_api(identifier, traits)
 
     def get_identity_segments(
-        self, identifier: str, traits: typing.Dict[str, typing.Any] = None
+        self,
+        identifier: str,
+        traits: typing.Optional[typing.Mapping[str, TraitValue]] = None,
     ) -> typing.List[Segment]:
         """
         Get a list of segments that the given identity is in.
@@ -255,7 +278,7 @@ def get_identity_segments(
         segment_models = get_identity_segments(self._environment, identity_model)
         return [Segment(id=sm.id, name=sm.name) for sm in segment_models]
 
-    def update_environment(self):
+    def update_environment(self) -> None:
         self._environment = self._get_environment_from_api()
         self._update_overrides()
 
@@ -272,16 +295,20 @@ def _get_environment_from_api(self) -> EnvironmentModel:
         return EnvironmentModel.model_validate(environment_data)
 
     def _get_environment_flags_from_document(self) -> Flags:
+        if self._environment is None:
+            raise TypeError("No environment present")
         return Flags.from_feature_state_models(
             feature_states=engine.get_environment_feature_states(self._environment),
             analytics_processor=self._analytics_processor,
             default_flag_handler=self.default_flag_handler,
         )
 
     def _get_identity_flags_from_document(
-        self, identifier: str, traits: typing.Dict[str, typing.Any]
+        self, identifier: str, traits: typing.Mapping[str, TraitValue]
     ) -> Flags:
         identity_model = self._get_identity_model(identifier, **traits)
+        if self._environment is None:
+            raise TypeError("No environment present")
         feature_states = engine.get_identity_feature_states(
             self._environment, identity_model
         )
@@ -294,11 +321,11 @@ def _get_identity_flags_from_document(
 
     def _get_environment_flags_from_api(self) -> Flags:
         try:
-            api_flags = self._get_json_response(
-                url=self.environment_flags_url, method="GET"
-            )
+            json_response: typing.List[
+                typing.Mapping[str, JsonType]
+            ] = self._get_json_response(url=self.environment_flags_url, method="GET")
             return Flags.from_api_flags(
-                api_flags=api_flags,
+                api_flags=json_response,
                 analytics_processor=self._analytics_processor,
                 default_flag_handler=self.default_flag_handler,
             )
@@ -310,11 +337,13 @@ def _get_environment_flags_from_api(self) -> Flags:
             raise
 
     def _get_identity_flags_from_api(
-        self, identifier: str, traits: typing.Dict[str, typing.Any]
+        self, identifier: str, traits: typing.Mapping[str, typing.Any]
     ) -> Flags:
         try:
             data = generate_identities_data(identifier, traits)
-            json_response = self._get_json_response(
+            json_response: typing.Dict[
+                str, typing.List[typing.Dict[str, JsonType]]
+            ] = self._get_json_response(
                 url=self.identities_url, method="POST", body=data
             )
             return Flags.from_api_flags(
@@ -329,7 +358,14 @@ def _get_identity_flags_from_api(
                 return Flags(default_flag_handler=self.default_flag_handler)
             raise
 
-    def _get_json_response(self, url: str, method: str, body: dict = None):
+    def _get_json_response(
+        self,
+        url: str,
+        method: str,
+        body: typing.Optional[
+            typing.Union[Identity, typing.Dict[str, JsonType]]
+        ] = None,
+    ) -> typing.Any:
         try:
             request_method = getattr(self.session, method.lower())
             response = request_method(
@@ -371,7 +407,7 @@ def _get_identity_model(
             identity_traits=trait_models,
         )
 
-    def __del__(self):
+    def __del__(self) -> None:
         if hasattr(self, "environment_data_polling_manager_thread"):
             self.environment_data_polling_manager_thread.stop()
 

flagsmith/models.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 import typing
 from dataclasses import dataclass, field
 
@@ -28,8 +30,8 @@ class Flag(BaseFlag):
     def from_feature_state_model(
         cls,
         feature_state_model: FeatureStateModel,
-        identity_id: typing.Union[str, int] = None,
-    ) -> "Flag":
+        identity_id: typing.Optional[typing.Union[str, int]] = None,
+    ) -> Flag:
         return Flag(
             enabled=feature_state_model.enabled,
             value=feature_state_model.get_value(identity_id=identity_id),
@@ -38,7 +40,7 @@ def from_feature_state_model(
         )
 
     @classmethod
-    def from_api_flag(cls, flag_data: dict) -> "Flag":
+    def from_api_flag(cls, flag_data: typing.Mapping[str, typing.Any]) -> Flag:
         return Flag(
             enabled=flag_data["enabled"],
             value=flag_data["feature_state_value"],
@@ -50,17 +52,17 @@ def from_api_flag(cls, flag_data: dict) -> "Flag":
 @dataclass
 class Flags:
     flags: typing.Dict[str, Flag] = field(default_factory=dict)
-    default_flag_handler: typing.Callable[[str], DefaultFlag] = None
-    _analytics_processor: AnalyticsProcessor = None
+    default_flag_handler: typing.Optional[typing.Callable[[str], DefaultFlag]] = None
+    _analytics_processor: typing.Optional[AnalyticsProcessor] = None
 
     @classmethod
     def from_feature_state_models(
         cls,
-        feature_states: typing.List[FeatureStateModel],
-        analytics_processor: AnalyticsProcessor,
-        default_flag_handler: typing.Callable,
-        identity_id: typing.Union[str, int] = None,
-    ) -> "Flags":
+        feature_states: typing.Sequence[FeatureStateModel],
+        analytics_processor: typing.Optional[AnalyticsProcessor],
+        default_flag_handler: typing.Optional[typing.Callable[[str], DefaultFlag]],
+        identity_id: typing.Optional[typing.Union[str, int]] = None,
+    ) -> Flags:
         flags = {
             feature_state.feature.name: Flag.from_feature_state_model(
                 feature_state, identity_id=identity_id
@@ -77,10 +79,10 @@ def from_feature_state_models(
     @classmethod
     def from_api_flags(
         cls,
-        api_flags: typing.List[dict],
-        analytics_processor: AnalyticsProcessor,
-        default_flag_handler: typing.Callable,
-    ) -> "Flags":
+        api_flags: typing.Sequence[typing.Mapping[str, typing.Any]],
+        analytics_processor: typing.Optional[AnalyticsProcessor],
+        default_flag_handler: typing.Optional[typing.Callable[[str], DefaultFlag]],
+    ) -> Flags:
         flags = {
             flag_data["feature"]["name"]: Flag.from_api_flag(flag_data)
             for flag_data in api_flags
@@ -120,12 +122,12 @@ def get_feature_value(self, feature_name: str) -> typing.Any:
         """
         return self.get_flag(feature_name).value
 
-    def get_flag(self, feature_name: str) -> BaseFlag:
+    def get_flag(self, feature_name: str) -> typing.Union[DefaultFlag, Flag]:
         """
         Get a specific flag given the feature name.
 
         :param feature_name: the name of the feature to retrieve the flag for.
-        :return: BaseFlag object.
+        :return: DefaultFlag | Flag object.
         :raises FlagsmithClientError: if feature doesn't exist
         """
         try: