Improve TriggerRuleDep typing and readability (#27810)

airflow/ti_deps/deps/base_ti_dep.py

@@ -17,11 +17,16 @@
 # under the License.
 from __future__ import annotations
 
-from typing import NamedTuple
+from typing import TYPE_CHECKING, Any, Iterator, NamedTuple
 
 from airflow.ti_deps.dep_context import DepContext
 from airflow.utils.session import provide_session
 
+if TYPE_CHECKING:
+    from sqlalchemy.orm import Session
+
+    from airflow.models.taskinstance import TaskInstance
+
 
 class BaseTIDep:
     """
@@ -38,27 +43,29 @@ class BaseTIDep:
     # to some tasks (e.g. depends_on_past is not specified by all tasks).
     IS_TASK_DEP = False
 
-    def __init__(self):
-        pass
-
-    def __eq__(self, other):
+    def __eq__(self, other: Any) -> bool:
         return isinstance(self, type(other))
 
-    def __hash__(self):
+    def __hash__(self) -> int:
         return hash(type(self))
 
-    def __repr__(self):
+    def __repr__(self) -> str:
         return f"<TIDep({self.name})>"
 
     @property
-    def name(self):
-        """
-        The human-readable name for the dependency. Use the classname as the default name
-        if this method is not overridden in the subclass.
+    def name(self) -> str:
+        """The human-readable name for the dependency.
+
+        Use the class name as the default if ``NAME`` is not provided.
         """
         return getattr(self, "NAME", self.__class__.__name__)
 
-    def _get_dep_statuses(self, ti, session, dep_context):
+    def _get_dep_statuses(
+        self,
+        ti: TaskInstance,
+        session: Session,
+        dep_context: DepContext,
+    ) -> Iterator[TIDepStatus]:
         """
         Abstract method that returns an iterable of TIDepStatus objects that describe
         whether the given task instance has this dependency met.
@@ -73,7 +80,12 @@ def _get_dep_statuses(self, ti, session, dep_context):
         raise NotImplementedError
 
     @provide_session
-    def get_dep_statuses(self, ti, session, dep_context=None):
+    def get_dep_statuses(
+        self,
+        ti: TaskInstance,
+        session: Session,
+        dep_context: DepContext | None = None,
+    ) -> Iterator[TIDepStatus]:
         """
         Wrapper around the private _get_dep_statuses method that contains some global
         checks for all dependencies.
@@ -82,21 +94,20 @@ def get_dep_statuses(self, ti, session, dep_context=None):
         :param session: database session
         :param dep_context: the context for which this dependency should be evaluated for
         """
-        if dep_context is None:
-            dep_context = DepContext()
+        cxt = DepContext() if dep_context is None else dep_context
 
-        if self.IGNORABLE and dep_context.ignore_all_deps:
+        if self.IGNORABLE and cxt.ignore_all_deps:
             yield self._passing_status(reason="Context specified all dependencies should be ignored.")
             return
 
-        if self.IS_TASK_DEP and dep_context.ignore_task_deps:
+        if self.IS_TASK_DEP and cxt.ignore_task_deps:
             yield self._passing_status(reason="Context specified all task dependencies should be ignored.")
             return
 
-        yield from self._get_dep_statuses(ti, session, dep_context)
+        yield from self._get_dep_statuses(ti, session, cxt)
 
     @provide_session
-    def is_met(self, ti, session, dep_context=None):
+    def is_met(self, ti: TaskInstance, session: Session, dep_context: DepContext | None = None) -> bool:
         """
         Returns whether or not this dependency is met for a given task instance. A
         dependency is considered met if all of the dependency statuses it reports are
@@ -110,7 +121,12 @@ def is_met(self, ti, session, dep_context=None):
         return all(status.passed for status in self.get_dep_statuses(ti, session, dep_context))
 
     @provide_session
-    def get_failure_reasons(self, ti, session, dep_context=None):
+    def get_failure_reasons(
+        self,
+        ti: TaskInstance,
+        session: Session,
+        dep_context: DepContext | None = None,
+    ) -> Iterator[str]:
         """
         Returns an iterable of strings that explain why this dependency wasn't met.
 
@@ -123,10 +139,10 @@ def get_failure_reasons(self, ti, session, dep_context=None):
             if not dep_status.passed:
                 yield dep_status.reason
 
-    def _failing_status(self, reason=""):
+    def _failing_status(self, reason: str = "") -> TIDepStatus:
         return TIDepStatus(self.name, False, reason)
 
-    def _passing_status(self, reason=""):
+    def _passing_status(self, reason: str = "") -> TIDepStatus:
         return TIDepStatus(self.name, True, reason)