[Dashing] Restore support for Python 3.5 (#324)

* Fix Python 3.5 compatibility by removing unsupported type hints.

Some of the type hints introduced in Dashing are not compatible with
Python 3.5. Where possible I tried to convert the hints to type comments
but for the type hints within function argument lists that did not
appear to be possible.

This is going to make backporting future changes more challenging since
we will have to:
1. Review the backported code for incompatible type hints
2. Reconcile merge conflicts caused by the removal of type hints on
the Dashing development branches.

* Convert list comprehension to generator (#300)

Addresses flake8 C412 errors introduced by flake8-comprehension 2.2.0

* Remove type comments longer than 100 chars.

It isn't clear to me from [PEP-0484] how to reconcile overlong lines
with type comments.

[PEP-0484]: https://www.python.org/dev/peps/pep-0484/

* Don't warn on imports used for type comments.

According to [PEP-0484] types used in type comments must be imported or
defined in the current module. Since flake8 is not type-comment aware
(at least in Dashing PR jobs) I've noqa'd the imports.

[PEP-0484]: https://www.python.org/dev/peps/pep-0484/

* Remove invalid trailing comma.

* Fix a test failure due to a change in how pytest represents exceptions.

This is a cherry-pick of 7b13334 from
#277 to resolve a test failing on CI.

Signed-off-by: Steven! Ragnarök <[email protected]>

Author: nuclearsandwich

launch/launch/actions/execute_process.py

@@ -197,7 +197,7 @@ def __init__(
                 self.__env.append((
                     normalize_to_list_of_substitutions(key),
                     normalize_to_list_of_substitutions(value)))
-        self.__additional_env: Optional[List[Tuple[List[Substitution], List[Substitution]]]] = None
+        self.__additional_env = None
         if additional_env is not None:
             self.__additional_env = []
             for key, value in additional_env.items():

launch/launch/launch_description.py

@@ -89,7 +89,7 @@ def process_entities(entities, *, _conditional_inclusion):
             for entity in entities:
                 if isinstance(entity, DeclareLaunchArgument):
                     # Avoid duplicate entries with the same name.
-                    if entity.name in [e.name for e in declared_launch_arguments]:
+                    if entity.name in (e.name for e in declared_launch_arguments):
                         continue
                     # Stuff this contextual information into the class for
                     # potential use in command-line descriptions or errors.

launch/launch/launch_description_source.py

@@ -16,7 +16,7 @@
 
 import traceback
 from typing import Optional
-from typing import Text
+from typing import Text  # noqa: F401
 
 import launch.logging
 
@@ -47,10 +47,10 @@ def __init__(
         :param location: the location from where this launch description was loaded if applicable
         :param method: the method by which the launch description was generated
         """
-        self.__launch_description: Optional[LaunchDescription] = launch_description
-        self.__expanded_location: Optional[Text] = None
-        self.__location: SomeSubstitutionsType = normalize_to_list_of_substitutions(location)
-        self.__method: str = method
+        self.__launch_description = launch_description  # type: Optional[LaunchDescription]
+        self.__expanded_location = None  # type: Optional[Text]
+        self.__location = normalize_to_list_of_substitutions(location)
+        self.__method = method  # type: str
         self.__logger = launch.logging.get_logger(__name__)
 
     def try_get_launch_description_without_context(self) -> Optional[LaunchDescription]:

launch/launch/logging/__init__.py

@@ -22,7 +22,7 @@
 import socket
 import sys
 
-from typing import List
+from typing import List  # noqa: F401
 
 from . import handlers
 
@@ -387,7 +387,7 @@ def _make_unique_log_dir(*, base_path):
 
 # Track all loggers to support module resets
 class LaunchLogger(logging.getLoggerClass()):
-    all_loggers: List[logging.Logger] = []
+    all_loggers = []  # type: List[logging.Logger]
 
     def __new__(cls, *args, **kwargs):
         instance = super(LaunchLogger, cls).__new__(cls)

launch/test/launch/actions/test_include_launch_description.py

@@ -110,7 +110,7 @@ def test_include_launch_description_launch_arguments():
     lc2 = LaunchContext()
     with pytest.raises(RuntimeError) as excinfo2:
         action2.visit(lc2)
-    assert 'Included launch description missing required argument' in str(excinfo2)
+    assert 'Included launch description missing required argument' in str(excinfo2.value)
 
     # test that a declared argument that is not provided raises an error, but with other args set
     ld2 = LaunchDescription([DeclareLaunchArgument('foo')])
@@ -121,8 +121,8 @@ def test_include_launch_description_launch_arguments():
     lc2 = LaunchContext()
     with pytest.raises(RuntimeError) as excinfo2:
         action2.visit(lc2)
-    assert 'Included launch description missing required argument' in str(excinfo2)
-    assert 'not_foo' in str(excinfo2)
+    assert 'Included launch description missing required argument' in str(excinfo2.value)
+    assert 'not_foo' in str(excinfo2.value)
 
     # test that a declared argument with a default value that is not provided does not raise
     ld2 = LaunchDescription([DeclareLaunchArgument('foo', default_value='FOO')])

launch_testing/launch_testing/io_handler.py

@@ -133,7 +133,7 @@ def waitFor(
         *,
         strict_proc_matching=True,
         output_filter=None,
-        timeout=10,
+        timeout=10
     ):
         success = False