Fix unreachable code mypy warnings in standard provider (#53431)

* Fix unreachable code mypy warnings in standard provider

* Revert removal of target_time in DateTimeSensor and adding reason for dead code

* Skip tests for branching from base class that are not branch-able

* Revert removal of target_time in DateTimeSensor and adding reason for dead code

* Review Feedback

Author: jscheffl

providers/standard/src/airflow/providers/standard/operators/branch.py

@@ -56,9 +56,7 @@ def _expand_task_group_roots(
         if TYPE_CHECKING:
             assert dag
 
-        if branches_to_execute is None:
-            return
-        elif isinstance(branches_to_execute, str) or not isinstance(branches_to_execute, Iterable):
+        if isinstance(branches_to_execute, str) or not isinstance(branches_to_execute, Iterable):
             branches_to_execute = [branches_to_execute]
 
         for branch in branches_to_execute:

providers/standard/src/airflow/providers/standard/sensors/date_time.py

@@ -99,8 +99,11 @@ def poke(self, context: Context) -> bool:
 
     @property
     def _moment(self) -> datetime.datetime:
-        if isinstance(self.target_time, datetime.datetime):
-            return self.target_time
+        # Note following is reachable code if Jinja is used for redering template fields and
+        # render_template_as_native_obj=True is used.
+        # In this case, the target_time is already a datetime object.
+        if isinstance(self.target_time, datetime.datetime):  # type:ignore[unreachable]
+            return self.target_time  # type:ignore[unreachable]
 
         return timezone.parse(self.target_time)
 

providers/standard/src/airflow/providers/standard/utils/python_virtualenv.py

@@ -21,7 +21,6 @@
 
 import os
 import shutil
-import sys
 from pathlib import Path
 
 import jinja2
@@ -56,9 +55,7 @@ def _use_uv() -> bool:
 
 def _generate_uv_cmd(tmp_dir: str, python_bin: str, system_site_packages: bool) -> list[str]:
     """Build the command to install the venv via UV."""
-    cmd = ["uv", "venv", "--allow-existing", "--seed"]
-    if python_bin is not None:
-        cmd += ["--python", python_bin]
+    cmd = ["uv", "venv", "--allow-existing", "--seed", "--python", python_bin]
     if system_site_packages:
         cmd.append("--system-site-packages")
     cmd.append(tmp_dir)
@@ -67,8 +64,6 @@ def _generate_uv_cmd(tmp_dir: str, python_bin: str, system_site_packages: bool)
 
 def _generate_venv_cmd(tmp_dir: str, python_bin: str, system_site_packages: bool) -> list[str]:
     """We are using venv command instead of venv module to allow creation of venv for different python versions."""
-    if python_bin is None:
-        python_bin = sys.executable
     cmd = [python_bin, "-m", "venv", tmp_dir]
     if system_site_packages:
         cmd.append("--system-site-packages")

providers/standard/tests/unit/standard/operators/test_python.py

@@ -1743,6 +1743,24 @@ def setup_tests(self):
         self.branch_1 = EmptyOperator(task_id="branch_1")
         self.branch_2 = EmptyOperator(task_id="branch_2")
 
+    # Skip some tests from base class that are not applicable for branching operators
+    # as the branching condition is mandatory but not given by base class
+    @pytest.mark.skip(reason="Test is not working for branching operators")
+    def test_string_args(self):
+        pass
+
+    @pytest.mark.skip(reason="Test is not working for branching operators")
+    def test_return_none(self):
+        pass
+
+    @pytest.mark.skip(reason="Test is not working for branching operators")
+    def test_nonimported_as_arg(self):
+        pass
+
+    @pytest.mark.skip(reason="Test is not working for branching operators")
+    def test_on_skip_exit_code(self):
+        pass
+
     def test_with_args(self):
         def f(a, b, c=False, d=False):
             if a == 0 and b == 1 and c and not d: