Static Type Checking Intro

.github/workflows/validate.yml

@@ -27,3 +27,5 @@ jobs:
     - name: Test with pytest
       run: |
         pytest tests --doctest-modules --cov-report=xml --cov-report=html
+    - name: cspell-action
+      uses: streetsidesoftware/[email protected]

.gitignore

@@ -411,3 +411,5 @@ docs/_static
 docs/_templates
 docs/doctrees
 docs/html
+package-lock.json
+package.json

cspell.config.yaml

@@ -0,0 +1,20 @@
+---
+$schema: https://raw.githubusercontent.com/streetsidesoftware/cspell/main/cspell.schema.json
+version: '0.2'
+dictionaryDefinitions:
+  - name: project-words
+    path: './project-words.txt'
+    addWords: true
+dictionaries:
+  - project-words
+ignorePaths:
+  - 'env'
+  - '.*'
+  - 'build'
+  - 'docs'
+  - 'dev_requirements.txt'
+  - '*.egg-info'
+  - '*.ini'
+  - '*.toml'
+  - 'SECURITY.md'
+  - 'SUPPORT.md'

featuremanagement/_defaultfilters.py

@@ -5,10 +5,9 @@
 # -------------------------------------------------------------------------
 import logging
 import hashlib
-
 from datetime import datetime, timezone
 from email.utils import parsedate_to_datetime
-
+from typing import cast, List, Mapping, Optional, Dict, Any
 from ._featurefilters import FeatureFilter
 
 FEATURE_FLAG_NAME_KEY = "feature_name"
@@ -45,7 +44,7 @@ class TimeWindowFilter(FeatureFilter):
     Feature Filter that determines if the current time is within the time window.
     """
 
-    def evaluate(self, context, **kwargs):
+    def evaluate(self, context: Mapping, **kwargs: Dict[str, Any]) -> bool:
         """
         Determine if the feature flag is enabled for the given context.
 
@@ -75,7 +74,7 @@ class TargetingFilter(FeatureFilter):
     """
 
     @staticmethod
-    def _is_targeted(context_id, rollout_percentage):
+    def _is_targeted(context_id: str, rollout_percentage: int) -> bool:
         """Determine if the user is targeted for the given context"""
         # Always return true if rollout percentage is 100
         if rollout_percentage == 100:
@@ -87,24 +86,29 @@ def _is_targeted(context_id, rollout_percentage):
         percentage = (context_marker / (2**32 - 1)) * 100
         return percentage < rollout_percentage
 
-    def _target_group(self, target_user, target_group, group, feature_flag_name):
+    def _target_group(
+        self, target_user: Optional[str], target_group: str, group: Mapping, feature_flag_name: str
+    ) -> bool:
         group_rollout_percentage = group.get(ROLLOUT_PERCENTAGE_KEY, 0)
         if not target_user:
             target_user = ""
         audience_context_id = target_user + "\n" + feature_flag_name + "\n" + target_group
 
         return self._is_targeted(audience_context_id, group_rollout_percentage)
 
-    def evaluate(self, context, **kwargs):
+    def evaluate(self, context: Mapping, **kwargs: Dict[str, Any]) -> bool:
         """
         Determine if the feature flag is enabled for the given context.
 
         :keyword Mapping context: Context for evaluating the user/group.
         :return: True if the user is targeted for the feature flag.
         :rtype: bool
         """
-        target_user = kwargs.get(TARGETED_USER_KEY, None)
-        target_groups = kwargs.get(TARGETED_GROUPS_KEY, [])
+        target_user: Optional[str] = cast(
+            str,
+            kwargs.get(TARGETED_USER_KEY, None),
+        )
+        target_groups: List[str] = cast(List[str], kwargs.get(TARGETED_GROUPS_KEY, []))
 
         if not target_user and not (target_groups and len(target_groups) > 0):
             logging.warning("%s: Name or Groups are required parameters", TargetingFilter.__name__)
@@ -152,7 +156,7 @@ def evaluate(self, context, **kwargs):
         return self._is_targeted(context_id, default_rollout_percentage)
 
     @staticmethod
-    def _validate(groups, default_rollout_percentage):
+    def _validate(groups: List, default_rollout_percentage: int) -> None:
         # Validate the audience settings
         if default_rollout_percentage < 0 or default_rollout_percentage > 100:
             raise TargetingException("DefaultRolloutPercentage must be between 0 and 100")

featuremanagement/_featurefilters.py

@@ -4,6 +4,7 @@
 # license information.
 # -------------------------------------------------------------------------
 from abc import ABC, abstractmethod
+from typing import Mapping, Callable, Dict, Any
 
 
 class FeatureFilter(ABC):
@@ -12,36 +13,36 @@ class FeatureFilter(ABC):
     """
 
     @abstractmethod
-    def evaluate(self, context, **kwargs):
+    def evaluate(self, context: Mapping, **kwargs: Dict[str, Any]) -> bool:
         """
         Determine if the feature flag is enabled for the given context.
 
         :param Mapping context: Context for the feature flag.
         """
 
     @property
-    def name(self):
+    def name(self) -> str:
         """
         Get the name of the filter.
 
         :return: Name of the filter, or alias if it exists.
         :rtype: str
         """
         if hasattr(self, "_alias"):
-            return self._alias
+            return self._alias  # type: ignore
         return self.__class__.__name__
 
     @staticmethod
-    def alias(alias):
+    def alias(alias: str) -> Callable:
         """
         Decorator to set the alias for the filter.
 
         :param str alias: Alias for the filter.
         :return: Decorator.
-        :rtype: callable
+        :rtype: Callable
         """
 
-        def wrapper(cls):
+        def wrapper(cls) -> Any:  # type: ignore
             cls._alias = alias  # pylint: disable=protected-access
             return cls
 

featuremanagement/_featuremanager.py

@@ -4,10 +4,10 @@
 # license information.
 # -------------------------------------------------------------------------
 import logging
-from typing import overload
+from typing import cast, overload, Any, Optional, Dict, Mapping, List
 from ._defaultfilters import TimeWindowFilter, TargetingFilter
 from ._featurefilters import FeatureFilter
-from ._models import EvaluationEvent
+from ._models import EvaluationEvent, Variant, TargetingContext
 from ._featuremanagerbase import (
     _get_feature_flag,
     FeatureManagerBase,
@@ -28,17 +28,17 @@ class FeatureManager(FeatureManagerBase):
     evaluated.
     """
 
-    def __init__(self, configuration, **kwargs):
+    def __init__(self, configuration: Mapping, **kwargs: Dict[str, Any]):
         super().__init__(configuration, **kwargs)
-        filters = [TimeWindowFilter(), TargetingFilter()] + kwargs.pop(PROVIDED_FEATURE_FILTERS, [])
+        filters = [TimeWindowFilter(), TargetingFilter()] + cast(List, kwargs.pop(PROVIDED_FEATURE_FILTERS, []))
 
         for feature_filter in filters:
             if not isinstance(feature_filter, FeatureFilter):
                 raise ValueError("Custom filter must be a subclass of FeatureFilter")
             self._filters[feature_filter.name] = feature_filter
 
-    @overload
-    def is_enabled(self, feature_flag_id, user_id, **kwargs):
+    @overload  # type: ignore
+    def is_enabled(self, feature_flag_id: str, user_id: str, **kwargs: Dict[str, Any]) -> bool:
         """
         Determine if the feature flag is enabled for the given context.
 
@@ -48,7 +48,7 @@ def is_enabled(self, feature_flag_id, user_id, **kwargs):
         :rtype: bool
         """
 
-    def is_enabled(self, feature_flag_id, *args, **kwargs):
+    def is_enabled(self, feature_flag_id: str, *args: Any, **kwargs: Dict[str, Any]) -> bool:  # type: ignore
         """
         Determine if the feature flag is enabled for the given context.
 
@@ -59,13 +59,18 @@ def is_enabled(self, feature_flag_id, *args, **kwargs):
         targeting_context = self._build_targeting_context(args)
 
         result = self._check_feature(feature_flag_id, targeting_context, **kwargs)
-        if self._on_feature_evaluated and result.feature.telemetry.enabled:
+        if (
+            self._on_feature_evaluated
+            and result.feature
+            and result.feature.telemetry.enabled
+            and callable(self._on_feature_evaluated)
+        ):
             result.user = targeting_context.user_id
             self._on_feature_evaluated(result)
         return result.enabled
 
-    @overload
-    def get_variant(self, feature_flag_id, user_id, **kwargs):
+    @overload  # type: ignore
+    def get_variant(self, feature_flag_id: str, user_id: str, **kwargs: Dict[str, Any]) -> Optional[Variant]:
         """
         Determine the variant for the given context.
 
@@ -75,7 +80,9 @@ def get_variant(self, feature_flag_id, user_id, **kwargs):
         :rtype: Variant
         """
 
-    def get_variant(self, feature_flag_id, *args, **kwargs):
+    def get_variant(  # type: ignore
+        self, feature_flag_id: str, *args: Any, **kwargs: Dict[str, Any]
+    ) -> Optional[Variant]:
         """
         Determine the variant for the given context.
 
@@ -87,13 +94,22 @@ def get_variant(self, feature_flag_id, *args, **kwargs):
         targeting_context = self._build_targeting_context(args)
 
         result = self._check_feature(feature_flag_id, targeting_context, **kwargs)
-        if self._on_feature_evaluated and result.feature.telemetry.enabled:
+        if (
+            self._on_feature_evaluated
+            and result.feature
+            and result.feature.telemetry.enabled
+            and callable(self._on_feature_evaluated)
+        ):
             result.user = targeting_context.user_id
             self._on_feature_evaluated(result)
         return result.variant
 
-    def _check_feature_filters(self, evaluation_event, targeting_context, **kwargs):
+    def _check_feature_filters(
+        self, evaluation_event: EvaluationEvent, targeting_context: TargetingContext, **kwargs: Dict
+    ) -> None:
         feature_flag = evaluation_event.feature
+        if not feature_flag:
+            return
         feature_conditions = feature_flag.conditions
         feature_filters = feature_conditions.client_filters
 
@@ -107,8 +123,8 @@ def _check_feature_filters(self, evaluation_event, targeting_context, **kwargs):
 
         for feature_filter in feature_filters:
             filter_name = feature_filter[FEATURE_FILTER_NAME]
-            kwargs["user"] = targeting_context.user_id
-            kwargs["groups"] = targeting_context.groups
+            kwargs["user"] = targeting_context.user_id  # type: ignore
+            kwargs["groups"] = targeting_context.groups  # type: ignore
             if filter_name not in self._filters:
                 raise ValueError(f"Feature flag {feature_flag.name} has unknown filter {filter_name}")
             if feature_conditions.requirement_type == REQUIREMENT_TYPE_ALL:
@@ -119,7 +135,9 @@ def _check_feature_filters(self, evaluation_event, targeting_context, **kwargs):
                 evaluation_event.enabled = True
                 break
 
-    def _check_feature(self, feature_flag_id, targeting_context, **kwargs):
+    def _check_feature(
+        self, feature_flag_id: str, targeting_context: TargetingContext, **kwargs: Dict[str, Any]
+    ) -> EvaluationEvent:
         """
         Determine if the feature flag is enabled for the given context.