Fixed Python 3.8 compatibility bugs; classmethod+property workaround; control session buffer

.coveragerc

@@ -1,14 +1,13 @@
 [run]
 source = src/
 branch = true
-omit =
-    .venv/*
+command_line = -m unittest discover
 
 [report]
+fail_under = 100
 show_missing = True
 skip_covered = False
 exclude_lines =
     if TYPE_CHECKING:
     if __name__ == ['"]__main__['"]:
-omit =
-    tests/*
+    if sys.version_info.+:

.github/workflows/main.yaml

@@ -0,0 +1,86 @@
+name: CI
+on: [push]
+jobs:
+  tests:
+    name: Python ${{ matrix.python-version }} Tests
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version:
+        - '3.8'
+        - '3.9'
+        - '3.10'
+    steps:
+    - uses: actions/checkout@v3
+
+    - uses: actions/setup-python@v3
+      with:
+        python-version: ${{ matrix.python-version }}
+        cache: 'pip'
+        cache-dependency-path: 'requirements/dev.txt'
+
+    - name: Upgrade packaging tools
+      run: pip install -U pip
+
+    - name: Install dependencies
+      run: pip install -U -r requirements/dev.txt
+
+    - name: Install asyncio-taskpool
+      run: pip install -e .
+
+    - name: Run tests for Python ${{ matrix.python-version }}
+      if: ${{ matrix.python-version != '3.10' }}
+      run: python -m tests
+
+    - name: Run tests for Python 3.10 and save coverage
+      if: ${{ matrix.python-version == '3.10' }}
+      run: echo "coverage=$(./coverage.sh)" >> $GITHUB_ENV
+    
+    outputs:
+      coverage: ${{ env.coverage }}
+
+  update_badges:
+    needs: tests
+    name: Update Badges
+    env:
+      meta_gist_id: 3f8240a976e8781a765d9c74a583dcda
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v3
+
+      - name: Download `cloc`
+        run: sudo apt-get update -y && sudo apt-get install -y cloc
+
+      - name: Count lines of code/comments
+        run: |
+          echo "cloc_code=$(./cloc.sh -c src/)" >> $GITHUB_ENV
+          echo "cloc_comments=$(./cloc.sh -m src/)" >> $GITHUB_ENV
+          echo "cloc_commentpercent=$(./cloc.sh -p src/)" >> $GITHUB_ENV
+
+      - name: Create badge for lines of code
+        uses: Schneegans/dynamic-badges-action@v1.2.0
+        with:
+          auth: ${{ secrets.GIST_META_DATA }}
+          gistID: ${{ env.meta_gist_id }}
+          filename: cloc-code.json
+          label: Lines of Code
+          message: ${{ env.cloc_code }}
+
+      - name: Create badge for lines of comments
+        uses: Schneegans/dynamic-badges-action@v1.2.0
+        with:
+          auth: ${{ secrets.GIST_META_DATA }}
+          gistID: ${{ env.meta_gist_id }}
+          filename: cloc-comments.json
+          label: Comments
+          message: ${{ env.cloc_comments }} (${{ env.cloc_commentpercent }}%)
+
+      - name: Create badge for test coverage
+        uses: Schneegans/dynamic-badges-action@v1.2.0
+        with:
+          auth: ${{ secrets.GIST_META_DATA }}
+          gistID: ${{ env.meta_gist_id }}
+          filename: test-coverage.json
+          label: Coverage
+          message: ${{ needs.tests.outputs.coverage }}

.readthedocs.yaml

@@ -0,0 +1,11 @@
+version: 2
+build:
+  os: 'ubuntu-20.04'
+  tools:
+    python: '3.8'
+python:
+  install:
+    - method: pip
+      path: .
+sphinx:
+  fail_on_warning: true

README.md

@@ -1,7 +1,30 @@
+[//]: # (This file is part of asyncio-taskpool.)
+
+[//]: # (asyncio-taskpool is free software: you can redistribute it and/or modify it under the terms of)
+[//]: # (version 3.0 of the GNU Lesser General Public License as published by the Free Software Foundation.)
+
+[//]: # (asyncio-taskpool is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;)
+[//]: # (without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.)
+[//]: # (See the GNU Lesser General Public License for more details.)
+
+[//]: # (You should have received a copy of the GNU Lesser General Public License along with asyncio-taskpool.)
+[//]: # (If not, see <https://www.gnu.org/licenses/>.)
+
 # asyncio-taskpool
 
+[![GitHub last commit][github-last-commit-img]][github-last-commit]
+![Lines of code][gist-cloc-code-img]
+![Lines of comments][gist-cloc-comments-img]
+![Test coverage][gist-test-coverage-img]
+[![License: LGPL v3.0][lgpl3-img]][lgpl3]
+[![PyPI version][pypi-latest-version-img]][pypi-latest-version]
+
 **Dynamically manage pools of asyncio tasks**
 
+Full documentation available at [RtD](https://asyncio-taskpool.readthedocs.io/en/latest).
+
+---
+
 ## Contents
 - [Contents](#contents)
 - [Summary](#summary)
@@ -55,8 +78,7 @@ Python Version 3.8+, tested on Linux
 
 ## Testing
 
-Install `asyncio-taskpool[dev]` dependencies or just manually install [`coverage`](https://coverage.readthedocs.io/en/latest/) with `pip`. 
-Execute the [`./coverage.sh`](coverage.sh) shell script to run all unit tests and receive the coverage report.
+Install [`coverage`](https://coverage.readthedocs.io/en/latest/) with `pip`, then execute the [`./coverage.sh`](coverage.sh) shell script to run all unit tests and save the coverage report.
 
 ## License
 
@@ -67,3 +89,13 @@ The full license texts for the [GNU GPLv3.0](COPYING) and the [GNU LGPLv3.0](COP
 ---
 
 © 2022 Daniil Fajnberg
+
+[github-last-commit]: https://github.com/daniil-berg/asyncio-taskpool/commits
+[github-last-commit-img]: https://img.shields.io/github/last-commit/daniil-berg/asyncio-taskpool?label=Last%20commit&logo=git&
+[gist-cloc-code-img]: https://img.shields.io/endpoint?logo=python&color=blue&url=https://gist.githubusercontent.com/daniil-berg/3f8240a976e8781a765d9c74a583dcda/raw/cloc-code.json
+[gist-cloc-comments-img]: https://img.shields.io/endpoint?logo=sharp&color=lightgrey&url=https://gist.githubusercontent.com/daniil-berg/3f8240a976e8781a765d9c74a583dcda/raw/cloc-comments.json
+[gist-test-coverage-img]: https://img.shields.io/endpoint?logo=pytest&color=blue&url=https://gist.githubusercontent.com/daniil-berg/3f8240a976e8781a765d9c74a583dcda/raw/test-coverage.json
+[lgpl3]: https://www.gnu.org/licenses/lgpl-3.0
+[lgpl3-img]: https://img.shields.io/badge/License-LGPL_v3.0-darkgreen.svg?logo=gnu
+[pypi-latest-version-img]: https://img.shields.io/pypi/v/asyncio-taskpool?color=teal&logo=pypi
+[pypi-latest-version]: https://pypi.org/project/asyncio-taskpool/

cloc.sh

@@ -0,0 +1,46 @@
+#!/usr/bin/env bash
+
+# This file is part of asyncio-taskpool.
+
+# asyncio-taskpool is free software: you can redistribute it and/or modify it under the terms of
+# version 3.0 of the GNU Lesser General Public License as published by the Free Software Foundation.
+
+# asyncio-taskpool is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+# without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+# See the GNU Lesser General Public License for more details.
+
+# You should have received a copy of the GNU Lesser General Public License along with asyncio-taskpool.
+# If not, see <https://www.gnu.org/licenses/>.
+
+typeset option
+if getopts 'bcmp' option; then
+  if [[ ${option} == [bcmp] ]]; then
+    shift
+  else
+    echo >&2 "Invalid option '$1' provided"
+    exit 1
+  fi
+fi
+
+typeset source=$1
+if [[ -z ${source} ]]; then
+  echo >&2 Source file/directory missing
+  exit 1
+fi
+
+typeset blank code comment commentpercent
+read blank comment code commentpercent < <( \
+  cloc --csv --quiet --hide-rate --include-lang Python ${source} |
+  awk -F, '$2 == "SUM" {printf ("%d %d %d %1.0f", $3, $4, $5, 100 * $4 / ($5 + $4)); exit}'
+)
+
+case ${option} in
+  b) echo ${blank} ;;
+  c) echo ${code} ;;
+  m) echo ${comment} ;;
+  p) echo ${commentpercent} ;;
+  *) echo Blank lines: ${blank}
+     echo Lines of comments: ${comment}
+     echo Lines of code: ${code}
+     echo Comment percentage: ${commentpercent} ;;
+esac

coverage.sh

@@ -1,3 +1,25 @@
-#!/usr/bin/env sh
+#!/usr/bin/env bash
 
-coverage erase && coverage run -m unittest discover && coverage report
+# This file is part of asyncio-taskpool.
+
+# asyncio-taskpool is free software: you can redistribute it and/or modify it under the terms of
+# version 3.0 of the GNU Lesser General Public License as published by the Free Software Foundation.
+
+# asyncio-taskpool is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+# without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+# See the GNU Lesser General Public License for more details.
+
+# You should have received a copy of the GNU Lesser General Public License along with asyncio-taskpool.
+# If not, see <https://www.gnu.org/licenses/>.
+
+coverage erase
+coverage run 2> /dev/null
+
+typeset report=$(coverage report)
+typeset total=$(echo "${report}" | awk '$1 == "TOTAL" {print $NF; exit}')
+
+if [[ ${total} == 100% ]]; then
+  echo ${total}
+else
+  echo "${report}"
+fi

docs/source/api/asyncio_taskpool.control.parser.rst

@@ -1,7 +0,0 @@
-asyncio\_taskpool.control.parser module
-=======================================
-
-.. automodule:: asyncio_taskpool.control.parser
-   :members:
-   :undoc-members:
-   :show-inheritance:

docs/source/api/asyncio_taskpool.control.rst

@@ -13,6 +13,4 @@ Submodules
    :maxdepth: 4
 
    asyncio_taskpool.control.client
-   asyncio_taskpool.control.parser
    asyncio_taskpool.control.server
-   asyncio_taskpool.control.session

docs/source/api/asyncio_taskpool.control.session.rst

@@ -1,7 +0,0 @@
-asyncio\_taskpool.control.session module
-========================================
-
-.. automodule:: asyncio_taskpool.control.session
-   :members:
-   :undoc-members:
-   :show-inheritance:

setup.cfg

@@ -1,6 +1,6 @@
 [metadata]
 name = asyncio-taskpool
-version = 1.0.0-beta
+version = 1.0.1
 author = Daniil Fajnberg
 author_email = mail@daniil.fajnberg.de
 description = Dynamically manage pools of asyncio tasks
@@ -11,7 +11,7 @@ url = https://git.fajnberg.de/daniil/asyncio-taskpool
 project_urls =
     Bug Tracker = https://github.com/daniil-berg/asyncio-taskpool/issues
 classifiers =
-    Development Status :: 4 - Beta
+    Development Status :: 5 - Production/Stable
     Programming Language :: Python :: 3
     Operating System :: OS Independent
     License :: OSI Approved :: GNU Lesser General Public License v3 (LGPLv3)

src/asyncio_taskpool/control/client.py

@@ -97,21 +97,22 @@ class ControlClient(ABC):
             writer: The `asyncio.StreamWriter` returned by the `_open_connection()` method
 
         Returns:
-            `None`, if either `Ctrl+C` was hit, or the user wants the client to disconnect;
-            otherwise, the user's input, stripped of leading and trailing spaces and converted to lowercase.
+            `None`, if either `Ctrl+C` was hit, an empty or whitespace-only string was entered, or the user wants the
+            client to disconnect; otherwise, returns the user's input, stripped of leading and trailing spaces and
+            converted to lowercase.
         """
         try:
-            msg = input("> ").strip().lower()
+            cmd = input("> ").strip().lower()
         except EOFError:  # Ctrl+D shall be equivalent to the :const:`CLIENT_EXIT` command.
-            msg = CLIENT_EXIT
+            cmd = CLIENT_EXIT
         except KeyboardInterrupt:  # Ctrl+C shall simply reset to the input prompt.
             print()
             return
-        if msg == CLIENT_EXIT:
+        if cmd == CLIENT_EXIT:
             writer.close()
             self._connected = False
             return
-        return msg
+        return cmd or None  # will be None if `cmd` is an empty string
 
     async def _interact(self, reader: StreamReader, writer: StreamWriter) -> None:
         """

src/asyncio_taskpool/control/parser.py

@@ -17,19 +17,21 @@ If not, see <https://www.gnu.org/licenses/>."""
 __doc__ = """
 Definition of the :class:`ControlParser` used in a 
 :class:`ControlSession <asyncio_taskpool.control.session.ControlSession>`.
+
+It should not be considered part of the public API.
 """
 
 
 import logging
 from argparse import Action, ArgumentParser, ArgumentDefaultsHelpFormatter, HelpFormatter, ArgumentTypeError, SUPPRESS
 from ast import literal_eval
-from asyncio.streams import StreamWriter
 from inspect import Parameter, getmembers, isfunction, signature
+from io import StringIO
 from shutil import get_terminal_size
 from typing import Any, Callable, Container, Dict, Iterable, Set, Type, TypeVar
 
 from ..exceptions import HelpRequested, ParserError
-from ..internals.constants import CLIENT_INFO, CMD, STREAM_WRITER
+from ..internals.constants import CLIENT_INFO, CMD
 from ..internals.helpers import get_first_doc_line, resolve_dotted_path
 from ..internals.types import ArgsT, CancelCB, CoroutineFunc, EndCB, KwArgsT
 
@@ -52,8 +54,8 @@ class ControlParser(ArgumentParser):
     """
     Subclass of the standard :code:`argparse.ArgumentParser` for pool control.
 
-    Such a parser is not supposed to ever print to stdout/stderr, but instead direct all messages to a `StreamWriter`
-    instance passed to it during initialization.
+    Such a parser is not supposed to ever print to stdout/stderr, but instead direct all messages to a file-like
+    `StringIO` instance passed to it during initialization.
     Furthermore, it requires defining the width of the terminal, to adjust help formatting to the terminal size of a
     connected client.
     Finally, it offers some convenience methods and makes use of custom exceptions.
@@ -87,25 +89,23 @@ class ControlParser(ArgumentParser):
                 super().__init__(*args, **kwargs)
         return ClientHelpFormatter
 
-    def __init__(self, stream_writer: StreamWriter, terminal_width: int = None, **kwargs) -> None:
+    def __init__(self, stream: StringIO, terminal_width: int = None, **kwargs) -> None:
         """
         Sets some internal attributes in addition to the base class.
 
         Args:
-            stream_writer:
-                The instance of the :class:`asyncio.StreamWriter` to use for message output.
+            stream:
+                A file-like I/O object to use for message output.
             terminal_width (optional):
                 The terminal width to use for all message formatting. By default the :code:`columns` attribute from
                 :func:`shutil.get_terminal_size` is taken.
             **kwargs(optional):
                 Passed to the parent class constructor. The exception is the `formatter_class` parameter: Even if a
                 class is specified, it will always be subclassed in the :meth:`help_formatter_factory`.
-                Also, by default, `exit_on_error` is set to `False` (as opposed to how the parent class handles it).
         """
-        self._stream_writer: StreamWriter = stream_writer
+        self._stream: StringIO = stream
         self._terminal_width: int = terminal_width if terminal_width is not None else get_terminal_size().columns
         kwargs['formatter_class'] = self.help_formatter_factory(self._terminal_width, kwargs.get('formatter_class'))
-        kwargs.setdefault('exit_on_error', False)
         super().__init__(**kwargs)
         self._flags: Set[str] = set()
         self._commands = None
@@ -194,7 +194,7 @@ class ControlParser(ArgumentParser):
             Dictionary mapping class member names to the (sub-)parsers created from them.
         """
         parsers: ParsersDict = {}
-        common_kwargs = {STREAM_WRITER: self._stream_writer, CLIENT_INFO.TERMINAL_WIDTH: self._terminal_width}
+        common_kwargs = {'stream': self._stream, CLIENT_INFO.TERMINAL_WIDTH: self._terminal_width}
         for name, member in getmembers(cls):
             if name in omit_members or (name.startswith('_') and public_only):
                 continue
@@ -214,9 +214,9 @@ class ControlParser(ArgumentParser):
         return self._commands
 
     def _print_message(self, message: str, *args, **kwargs) -> None:
-        """This is overridden to ensure that no messages are sent to stdout/stderr, but always to the stream writer."""
+        """This is overridden to ensure that no messages are sent to stdout/stderr, but always to the stream buffer."""
         if message:
-            self._stream_writer.write(message.encode())
+            self._stream.write(message)
 
     def exit(self, status: int = 0, message: str = None) -> None:
         """This is overridden to prevent system exit to be invoked."""

src/asyncio_taskpool/control/server.py

@@ -31,6 +31,7 @@ from typing import Optional, Union
 from .client import ControlClient, TCPControlClient, UnixControlClient
 from .session import ControlSession
 from ..pool import AnyTaskPoolT
+from ..internals.helpers import classmethod
 from ..internals.types import ConnectedCallbackT, PathT
 
 

src/asyncio_taskpool/control/session.py

@@ -16,6 +16,8 @@ If not, see <https://www.gnu.org/licenses/>."""
 
 __doc__ = """
 Definition of the :class:`ControlSession` used by a :class:`ControlServer`.
+
+It should not be considered part of the public API.
 """
 
 
@@ -24,12 +26,13 @@ import json
 from argparse import ArgumentError
 from asyncio.streams import StreamReader, StreamWriter
 from inspect import isfunction, signature
+from io import StringIO
 from typing import Callable, Optional, Union, TYPE_CHECKING
 
 from .parser import ControlParser
 from ..exceptions import CommandError, HelpRequested, ParserError
 from ..pool import TaskPool, SimpleTaskPool
-from ..internals.constants import CLIENT_INFO, CMD, CMD_OK, SESSION_MSG_BYTES, STREAM_WRITER
+from ..internals.constants import CLIENT_INFO, CMD, CMD_OK, SESSION_MSG_BYTES
 from ..internals.helpers import return_or_exception
 
 if TYPE_CHECKING:
@@ -72,6 +75,7 @@ class ControlSession:
         self._reader: StreamReader = reader
         self._writer: StreamWriter = writer
         self._parser: Optional[ControlParser] = None
+        self._response_buffer: StringIO = StringIO()
 
     async def _exec_method_and_respond(self, method: Callable, **kwargs) -> None:
         """
@@ -133,7 +137,7 @@ class ControlSession:
         client_info = json.loads((await self._reader.read(SESSION_MSG_BYTES)).decode().strip())
         log.debug("%s connected", self._client_class_name)
         parser_kwargs = {
-            STREAM_WRITER: self._writer,
+            'stream': self._response_buffer,
             CLIENT_INFO.TERMINAL_WIDTH: client_info[CLIENT_INFO.TERMINAL_WIDTH],
             'prog': '',
             'usage': f'[-h] [{CMD}] ...'
@@ -160,7 +164,7 @@ class ControlSession:
             kwargs = vars(self._parser.parse_args(msg.split(' ')))
         except ArgumentError as e:
             log.debug("%s got an ArgumentError", self._client_class_name)
-            self._writer.write(str(e).encode())
+            self._response_buffer.write(str(e))
             return
         except (HelpRequested, ParserError):
             log.debug("%s received usage help", self._client_class_name)
@@ -171,7 +175,7 @@ class ControlSession:
         elif isinstance(command, property):
             await self._exec_property_and_respond(command, **kwargs)
         else:
-            self._writer.write(str(CommandError(f"Unknown command object: {command}")).encode())
+            self._response_buffer.write(str(CommandError(f"Unknown command object: {command}")))
 
     async def listen(self) -> None:
         """
@@ -188,4 +192,8 @@ class ControlSession:
                 log.debug("%s disconnected", self._client_class_name)
                 break
             await self._parse_command(msg)
+            response = self._response_buffer.getvalue()
+            self._response_buffer.seek(0)
+            self._response_buffer.truncate()
+            self._writer.write(response.encode())
             await self._writer.drain()

src/asyncio_taskpool/internals/constants.py

@@ -27,7 +27,6 @@ DEFAULT_TASK_GROUP = 'default'
 
 SESSION_MSG_BYTES = 1024 * 100
 
-STREAM_WRITER = 'stream_writer'
 CMD = 'command'
 CMD_OK = b"ok"
 

src/asyncio_taskpool/internals/helpers.py

@@ -19,10 +19,12 @@ Miscellaneous helper functions. None of these should be considered part of the p
 """
 
 
+import builtins
+import sys
 from asyncio.coroutines import iscoroutinefunction
 from importlib import import_module
 from inspect import getdoc
-from typing import Any, Optional, Union
+from typing import Any, Callable, Optional, Type, Union
 
 from .types import T, AnyCallableT, ArgsT, KwArgsT
 
@@ -131,3 +133,25 @@ def resolve_dotted_path(dotted_path: str) -> object:
             import_module(module_name)
             found = getattr(found, name)
     return found
+
+
+class ClassMethodWorkaround:
+    """Dirty workaround to make the `@classmethod` decorator work with properties."""
+
+    def __init__(self, method_or_property: Union[Callable, property]) -> None:
+        if isinstance(method_or_property, property):
+            self._getter = method_or_property.fget
+        else:
+            self._getter = method_or_property
+
+    def __get__(self, obj: Union[T, None], cls: Union[Type[T], None]) -> Any:
+        if obj is None:
+            return self._getter(cls)
+        return self._getter(obj)
+
+
+# Starting with Python 3.9, this is thankfully no longer necessary.
+if sys.version_info[:2] < (3, 9):
+    classmethod = ClassMethodWorkaround
+else:
+    classmethod = builtins.classmethod

src/asyncio_taskpool/internals/types.py

@@ -23,7 +23,7 @@ This module should **not** be considered part of the public API.
 
 from asyncio.streams import StreamReader, StreamWriter
 from pathlib import Path
-from typing import Any, Awaitable, Callable, Iterable, Mapping, Tuple, TypeVar, Union
+from typing import Any, Awaitable, Callable, Coroutine, Iterable, Mapping, Tuple, TypeVar, Union
 
 
 T = TypeVar('T')
@@ -31,8 +31,8 @@ T = TypeVar('T')
 ArgsT = Iterable[Any]
 KwArgsT = Mapping[str, Any]
 
-AnyCallableT = Callable[[...], Union[T, Awaitable[T]]]
-CoroutineFunc = Callable[[...], Awaitable[Any]]
+AnyCallableT = Callable[..., Union[T, Awaitable[T]]]
+CoroutineFunc = Callable[..., Coroutine]
 
 EndCB = Callable
 CancelCB = Callable

src/asyncio_taskpool/pool.py

@@ -326,6 +326,8 @@ class BaseTaskPool:
         """
         self._check_start(awaitable=awaitable, ignore_lock=ignore_lock)
         await self._enough_room.acquire()
+        # TODO: Make sure that cancellation (group or pool) interrupts this method after context switching!
+        #       Possibly make use of the task group register for that.
         group_reg = self._task_groups.setdefault(group_name, TaskGroupRegister())
         async with group_reg:
             task_id = self._num_started
@@ -528,6 +530,8 @@ class BaseTaskPool:
         self._tasks_cancelled.clear()
         self._tasks_running.clear()
         self._closed = True
+        # TODO: Turn the `_closed` attribute into an `Event` and add something like a `until_closed` method that will
+        #       await it to allow blocking until a closing command comes from a server.
 
 
 class TaskPool(BaseTaskPool):
@@ -566,36 +570,50 @@ class TaskPool(BaseTaskPool):
                 return name
             i += 1
 
-    async def _apply_num(self, group_name: str, func: CoroutineFunc, args: ArgsT = (), kwargs: KwArgsT = None,
-                         num: int = 1, end_callback: EndCB = None, cancel_callback: CancelCB = None) -> None:
+    async def _apply_spawner(self, group_name: str, func: CoroutineFunc, args: ArgsT = (), kwargs: KwArgsT = None,
+                             num: int = 1, end_callback: EndCB = None, cancel_callback: CancelCB = None) -> None:
         """
-        Creates a coroutine with the supplied arguments and runs it as a new task in the pool.
+        Creates coroutines with the supplied arguments and runs them as new tasks in the pool.
 
         This method blocks, **only if** the pool has not enough room to accommodate `num` new tasks.
 
         Args:
             group_name:
-                Name of the task group to add the new task to.
+                Name of the task group to add the new tasks to.
             func:
-                The coroutine function to be run as a task within the task pool.
+                The coroutine function to be run in `num` tasks within the task pool.
             args (optional):
-                The positional arguments to pass into the function call.
+                The positional arguments to pass into each function call.
             kwargs (optional):
-                The keyword-arguments to pass into the function call.
+                The keyword-arguments to pass into each function call.
             num (optional):
                 The number of tasks to spawn with the specified parameters.
             end_callback (optional):
-                A callback to execute after the task has ended.
+                A callback to execute after each task has ended.
                 It is run with the task's ID as its only positional argument.
             cancel_callback (optional):
-                A callback to execute after cancellation of the task.
+                A callback to execute after cancellation of each task.
                 It is run with the task's ID as its only positional argument.
         """
         if kwargs is None:
             kwargs = {}
-        # TODO: Add exception logging
-        await gather(*(self._start_task(func(*args, **kwargs), group_name=group_name, end_callback=end_callback,
-                                        cancel_callback=cancel_callback) for _ in range(num)))
+        for i in range(num):
+            try:
+                coroutine = func(*args, **kwargs)
+            except Exception as e:
+                # This means there was probably something wrong with the function arguments.
+                log.exception("%s occurred in group '%s' while trying to create coroutine: %s(*%s, **%s)",
+                              str(e.__class__.__name__), group_name, func.__name__, repr(args), repr(kwargs))
+                continue
+            try:
+                await self._start_task(coroutine, group_name=group_name, end_callback=end_callback,
+                                       cancel_callback=cancel_callback)
+            except CancelledError:
+                # Either the task group or all tasks were cancelled, so this meta tasks is not supposed to spawn any
+                # more tasks and can return immediately.
+                log.debug("Cancelled group '%s' after %s out of %s tasks have been spawned", group_name, i, num)
+                coroutine.close()
+                return
 
     def apply(self, func: CoroutineFunc, args: ArgsT = (), kwargs: KwArgsT = None, num: int = 1, group_name: str = None,
               end_callback: EndCB = None, cancel_callback: CancelCB = None) -> str:
@@ -622,7 +640,7 @@ class TaskPool(BaseTaskPool):
             kwargs (optional):
                 The keyword-arguments to pass into each function call.
             num (optional):
-                The number of tasks to spawn with the specified parameters.
+                The number of tasks to spawn with the specified parameters. Defaults to 1.
             group_name (optional):
                 Name of the task group to add the new tasks to. By default, a unique name is constructed in the form
                 :code:`'apply-{name}-group-{idx}'` (with `name` being the name of the `func` and `idx` being an
@@ -650,8 +668,8 @@ class TaskPool(BaseTaskPool):
             raise exceptions.InvalidGroupName(f"Group named {group_name} already exists!")
         self._task_groups.setdefault(group_name, TaskGroupRegister())
         meta_tasks = self._group_meta_tasks_running.setdefault(group_name, set())
-        meta_tasks.add(create_task(self._apply_num(group_name, func, args, kwargs, num,
-                                                   end_callback=end_callback, cancel_callback=cancel_callback)))
+        meta_tasks.add(create_task(self._apply_spawner(group_name, func, args, kwargs, num,
+                                                       end_callback=end_callback, cancel_callback=cancel_callback)))
         return group_name
 
     @staticmethod
@@ -690,27 +708,31 @@ class TaskPool(BaseTaskPool):
                 The callback that was specified to execute after cancellation of the task (and the next one).
                 It is run with the task's ID as its only positional argument.
         """
-        map_semaphore = Semaphore(num_concurrent)
-        release_cb = self._get_map_end_callback(map_semaphore, actual_end_callback=end_callback)
-        for next_arg in arg_iter:
-            # When the number of running tasks spawned by this method reaches the specified maximum,
-            # this next line will block, until one of them ends and releases the semaphore.
-            await map_semaphore.acquire()
+        semaphore = Semaphore(num_concurrent)
+        release_cb = self._get_map_end_callback(semaphore, actual_end_callback=end_callback)
+        for i, next_arg in enumerate(arg_iter):
+            semaphore_acquired = False
             try:
-                await self._start_task(star_function(func, next_arg, arg_stars=arg_stars), group_name=group_name,
-                                       ignore_lock=True, end_callback=release_cb, cancel_callback=cancel_callback)
-            except CancelledError:
-                # This means that no more tasks are supposed to be created from this `arg_iter`;
-                # thus, we can forget about the rest of the arguments.
-                log.debug("Cancelled consumption of argument iterable in task group '%s'", group_name)
-                map_semaphore.release()
-                return
+                coroutine = star_function(func, next_arg, arg_stars=arg_stars)
             except Exception as e:
-                # This means an exception occurred during task **creation**, meaning no task has been created.
-                # It does not imply an error within the task itself.
-                log.exception("%s occurred while trying to create task: %s(%s%s)",
-                              str(e.__class__.__name__), func.__name__, '*' * arg_stars, str(next_arg))
-                map_semaphore.release()
+                # This means there was probably something wrong with the function arguments.
+                log.exception("%s occurred in group '%s' while trying to create coroutine: %s(%s%s)",
+                              str(e.__class__.__name__), group_name, func.__name__, '*' * arg_stars, str(next_arg))
+                continue
+            try:
+                # When the number of running tasks spawned by this method reaches the specified maximum,
+                # this next line will block, until one of them ends and releases the semaphore.
+                semaphore_acquired = await semaphore.acquire()
+                await self._start_task(coroutine, group_name=group_name, ignore_lock=True,
+                                       end_callback=release_cb, cancel_callback=cancel_callback)
+            except CancelledError:
+                # Either the task group or all tasks were cancelled, so this meta tasks is not supposed to spawn any
+                # more tasks and can return immediately. (This means we drop `arg_iter` without consuming it fully.)
+                log.debug("Cancelled group '%s' after %s tasks have been spawned", group_name, i)
+                coroutine.close()
+                if semaphore_acquired:
+                    semaphore.release()
+                return
 
     def _map(self, group_name: str, num_concurrent: int, func: CoroutineFunc, arg_iter: ArgsT, arg_stars: int,
              end_callback: EndCB = None, cancel_callback: CancelCB = None) -> None:
@@ -924,6 +946,7 @@ class SimpleTaskPool(BaseTaskPool):
                              end_callback=self._end_callback, cancel_callback=self._cancel_callback)
             for _ in range(num)
         )
+        # TODO: Same deal as with the other meta tasks, provide proper cancellation handling!
         await gather(*start_coroutines)
 
     def start(self, num: int) -> str:

tests/__main__.py

@@ -0,0 +1,30 @@
+__author__ = "Daniil Fajnberg"
+__copyright__ = "Copyright © 2022 Daniil Fajnberg"
+__license__ = """GNU LGPLv3.0
+
+This file is part of asyncio-taskpool.
+
+asyncio-taskpool is free software: you can redistribute it and/or modify it under the terms of
+version 3.0 of the GNU Lesser General Public License as published by the Free Software Foundation.
+
+asyncio-taskpool is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; 
+without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 
+See the GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along with asyncio-taskpool. 
+If not, see <https://www.gnu.org/licenses/>."""
+
+__doc__ = """
+Main entry point for all unit tests.
+"""
+
+
+import sys
+import unittest
+
+
+if __name__ == '__main__':
+    test_suite = unittest.defaultTestLoader.discover('.')
+    test_runner = unittest.TextTestRunner(resultclass=unittest.TextTestResult)
+    result = test_runner.run(test_suite)
+    sys.exit(not result.wasSuccessful())

tests/test_control/test___main__.py

@@ -38,7 +38,7 @@ class CLITestCase(IsolatedAsyncioTestCase):
         mock_client = MagicMock(start=mock_client_start)
         mock_client_cls = MagicMock(return_value=mock_client)
         mock_client_kwargs = {'foo': 123, 'bar': 456, 'baz': 789}
-        mock_parse_cli.return_value = {module.CLIENT_CLASS: mock_client_cls} | mock_client_kwargs
+        mock_parse_cli.return_value = {module.CLIENT_CLASS: mock_client_cls, **mock_client_kwargs}
         self.assertIsNone(await module.main())
         mock_parse_cli.assert_called_once_with()
         mock_client_cls.assert_called_once_with(**mock_client_kwargs)

tests/test_control/test_parser.py

@@ -41,9 +41,9 @@ class ControlParserTestCase(TestCase):
         self.help_formatter_factory_patcher = patch.object(parser.ControlParser, 'help_formatter_factory')
         self.mock_help_formatter_factory = self.help_formatter_factory_patcher.start()
         self.mock_help_formatter_factory.return_value = RawTextHelpFormatter
-        self.stream_writer, self.terminal_width = MagicMock(), 420
+        self.stream, self.terminal_width = MagicMock(), 420
         self.kwargs = {
-            'stream_writer': self.stream_writer,
+            'stream': self.stream,
             'terminal_width': self.terminal_width,
             'formatter_class': FOO
         }
@@ -72,10 +72,9 @@ class ControlParserTestCase(TestCase):
 
     def test_init(self):
         self.assertIsInstance(self.parser, ArgumentParser)
-        self.assertEqual(self.stream_writer, self.parser._stream_writer)
+        self.assertEqual(self.stream, self.parser._stream)
         self.assertEqual(self.terminal_width, self.parser._terminal_width)
         self.mock_help_formatter_factory.assert_called_once_with(self.terminal_width, FOO)
-        self.assertFalse(getattr(self.parser, 'exit_on_error'))
         self.assertEqual(RawTextHelpFormatter, getattr(self.parser, 'formatter_class'))
         self.assertSetEqual(set(), self.parser._flags)
         self.assertIsNone(self.parser._commands)
@@ -89,7 +88,7 @@ class ControlParserTestCase(TestCase):
         mock_get_first_doc_line.return_value = mock_help = 'help 123'
         kwargs = {FOO: 1, BAR: 2, parser.DESCRIPTION: FOO + BAR}
         expected_name = 'foo-bar'
-        expected_kwargs = {parser.NAME: expected_name, parser.PROG: expected_name, parser.HELP: mock_help} | kwargs
+        expected_kwargs = {parser.NAME: expected_name, parser.PROG: expected_name, parser.HELP: mock_help, **kwargs}
         to_omit = ['abc', 'xyz']
         output = self.parser.add_function_command(foo_bar, omit_params=to_omit, **kwargs)
         self.assertEqual(mock_subparser, output)
@@ -107,7 +106,7 @@ class ControlParserTestCase(TestCase):
         mock_get_first_doc_line.return_value = mock_help = 'help 123'
         kwargs = {FOO: 1, BAR: 2, parser.DESCRIPTION: FOO + BAR}
         expected_name = 'get-prop'
-        expected_kwargs = {parser.NAME: expected_name, parser.PROG: expected_name, parser.HELP: mock_help} | kwargs
+        expected_kwargs = {parser.NAME: expected_name, parser.PROG: expected_name, parser.HELP: mock_help, **kwargs}
         output = self.parser.add_property_command(prop, **kwargs)
         self.assertEqual(mock_subparser, output)
         mock_get_first_doc_line.assert_called_once_with(get_prop)
@@ -119,7 +118,7 @@ class ControlParserTestCase(TestCase):
 
         prop = property(get_prop, set_prop)
         expected_help = f"Get/set the `.{expected_name}` property"
-        expected_kwargs = {parser.NAME: expected_name, parser.PROG: expected_name, parser.HELP: expected_help} | kwargs
+        expected_kwargs = {parser.NAME: expected_name, parser.PROG: expected_name, parser.HELP: expected_help, **kwargs}
         output = self.parser.add_property_command(prop, **kwargs)
         self.assertEqual(mock_subparser, output)
         mock_get_first_doc_line.assert_has_calls([call(get_prop), call(set_prop)])
@@ -152,8 +151,7 @@ class ControlParserTestCase(TestCase):
         mock_subparser = MagicMock(set_defaults=mock_set_defaults)
         mock_add_function_command.return_value = mock_add_property_command.return_value = mock_subparser
         x = 'x'
-        common_kwargs = {parser.STREAM_WRITER: self.parser._stream_writer,
-                         parser.CLIENT_INFO.TERMINAL_WIDTH: self.parser._terminal_width}
+        common_kwargs = {'stream': self.parser._stream, parser.CLIENT_INFO.TERMINAL_WIDTH: self.parser._terminal_width}
         expected_output = {'method': mock_subparser, 'prop': mock_subparser}
         output = self.parser.add_class_commands(FooBar, public_only=True, omit_members=['to_omit'], member_arg_name=x)
         self.assertDictEqual(expected_output, output)
@@ -170,12 +168,12 @@ class ControlParserTestCase(TestCase):
         mock_base_add_subparsers.assert_called_once_with(*args, **kwargs)
 
     def test__print_message(self):
-        self.stream_writer.write = MagicMock()
+        self.stream.write = MagicMock()
         self.assertIsNone(self.parser._print_message(''))
-        self.stream_writer.write.assert_not_called()
+        self.stream.write.assert_not_called()
         msg = 'foo bar baz'
         self.assertIsNone(self.parser._print_message(msg))
-        self.stream_writer.write.assert_called_once_with(msg.encode())
+        self.stream.write.assert_called_once_with(msg)
 
     @patch.object(parser.ControlParser, '_print_message')
     def test_exit(self, mock__print_message: MagicMock):

tests/test_control/test_session.py

@@ -21,11 +21,12 @@ Unittests for the `asyncio_taskpool.session` module.
 
 import json
 from argparse import ArgumentError, Namespace
+from io import StringIO
 from unittest import IsolatedAsyncioTestCase
 from unittest.mock import AsyncMock, MagicMock, patch, call
 
 from asyncio_taskpool.control import session
-from asyncio_taskpool.internals.constants import CLIENT_INFO, CMD, SESSION_MSG_BYTES, STREAM_WRITER
+from asyncio_taskpool.internals.constants import CLIENT_INFO, CMD, SESSION_MSG_BYTES
 from asyncio_taskpool.exceptions import HelpRequested
 from asyncio_taskpool.pool import SimpleTaskPool
 
@@ -61,14 +62,15 @@ class ControlServerTestCase(IsolatedAsyncioTestCase):
         self.assertEqual(self.mock_reader, self.session._reader)
         self.assertEqual(self.mock_writer, self.session._writer)
         self.assertIsNone(self.session._parser)
+        self.assertIsInstance(self.session._response_buffer, StringIO)
 
     @patch.object(session, 'return_or_exception')
     async def test__exec_method_and_respond(self, mock_return_or_exception: AsyncMock):
         def method(self, arg1, arg2, *var_args, **rest): pass
         test_arg1, test_arg2, test_var_args, test_rest = 123, 'xyz', [0.1, 0.2, 0.3], {'aaa': 1, 'bbb': 11}
-        kwargs = {'arg1': test_arg1, 'arg2': test_arg2, 'var_args': test_var_args} | test_rest
+        kwargs = {'arg1': test_arg1, 'arg2': test_arg2, 'var_args': test_var_args}
         mock_return_or_exception.return_value = None
-        self.assertIsNone(await self.session._exec_method_and_respond(method, **kwargs))
+        self.assertIsNone(await self.session._exec_method_and_respond(method, **kwargs, **test_rest))
         mock_return_or_exception.assert_awaited_once_with(
             method, self.mock_pool, test_arg1, test_arg2, *test_var_args, **test_rest
         )
@@ -104,7 +106,7 @@ class ControlServerTestCase(IsolatedAsyncioTestCase):
         self.mock_reader.read = mock_read
         self.mock_writer.drain = AsyncMock()
         expected_parser_kwargs = {
-            STREAM_WRITER: self.mock_writer,
+            'stream': self.session._response_buffer,
             CLIENT_INFO.TERMINAL_WIDTH: width,
             'prog': '',
             'usage': f'[-h] [{CMD}] ...'
@@ -132,10 +134,9 @@ class ControlServerTestCase(IsolatedAsyncioTestCase):
         kwargs = {FOO: BAR, 'hello': 'python'}
         mock_parse_args = MagicMock(return_value=Namespace(**{CMD: method}, **kwargs))
         self.session._parser = MagicMock(parse_args=mock_parse_args)
-        self.mock_writer.write = MagicMock()
         self.assertIsNone(await self.session._parse_command(msg))
         mock_parse_args.assert_called_once_with(msg.split(' '))
-        self.mock_writer.write.assert_not_called()
+        self.assertEqual('', self.session._response_buffer.getvalue())
         mock__exec_method_and_respond.assert_awaited_once_with(method, **kwargs)
         mock__exec_property_and_respond.assert_not_called()
 
@@ -145,7 +146,7 @@ class ControlServerTestCase(IsolatedAsyncioTestCase):
         mock_parse_args.return_value = Namespace(**{CMD: prop}, **kwargs)
         self.assertIsNone(await self.session._parse_command(msg))
         mock_parse_args.assert_called_once_with(msg.split(' '))
-        self.mock_writer.write.assert_not_called()
+        self.assertEqual('', self.session._response_buffer.getvalue())
         mock__exec_method_and_respond.assert_not_called()
         mock__exec_property_and_respond.assert_awaited_once_with(prop, **kwargs)
 
@@ -161,26 +162,28 @@ class ControlServerTestCase(IsolatedAsyncioTestCase):
         mock_parse_args.assert_called_once_with(msg.split(' '))
         mock__exec_method_and_respond.assert_not_called()
         mock__exec_property_and_respond.assert_not_called()
-        self.mock_writer.write.assert_called_once_with(str(exc).encode())
+        self.assertEqual(str(exc), self.session._response_buffer.getvalue())
 
         mock__exec_property_and_respond.reset_mock()
         mock_parse_args.reset_mock()
-        self.mock_writer.write.reset_mock()
+        self.session._response_buffer.seek(0)
+        self.session._response_buffer.truncate()
 
         mock_parse_args.side_effect = exc = ArgumentError(MagicMock(), "oops")
         self.assertIsNone(await self.session._parse_command(msg))
         mock_parse_args.assert_called_once_with(msg.split(' '))
-        self.mock_writer.write.assert_called_once_with(str(exc).encode())
+        self.assertEqual(str(exc), self.session._response_buffer.getvalue())
         mock__exec_method_and_respond.assert_not_awaited()
         mock__exec_property_and_respond.assert_not_awaited()
 
-        self.mock_writer.write.reset_mock()
         mock_parse_args.reset_mock()
+        self.session._response_buffer.seek(0)
+        self.session._response_buffer.truncate()
 
         mock_parse_args.side_effect = HelpRequested()
         self.assertIsNone(await self.session._parse_command(msg))
         mock_parse_args.assert_called_once_with(msg.split(' '))
-        self.mock_writer.write.assert_not_called()
+        self.assertEqual('', self.session._response_buffer.getvalue())
         mock__exec_method_and_respond.assert_not_awaited()
         mock__exec_property_and_respond.assert_not_awaited()
 
@@ -191,17 +194,23 @@ class ControlServerTestCase(IsolatedAsyncioTestCase):
         self.mock_writer.drain = AsyncMock(side_effect=make_reader_return_empty)
         msg = "fascinating"
         self.mock_reader.read = AsyncMock(return_value=f' {msg} '.encode())
+        response = FOO + BAR + FOO
+        self.session._response_buffer.write(response)
         self.assertIsNone(await self.session.listen())
         self.mock_reader.read.assert_has_awaits([call(SESSION_MSG_BYTES), call(SESSION_MSG_BYTES)])
         mock__parse_command.assert_awaited_once_with(msg)
+        self.assertEqual('', self.session._response_buffer.getvalue())
+        self.mock_writer.write.assert_called_once_with(response.encode())
         self.mock_writer.drain.assert_awaited_once_with()
 
         self.mock_reader.read.reset_mock()
         mock__parse_command.reset_mock()
+        self.mock_writer.write.reset_mock()
         self.mock_writer.drain.reset_mock()
 
         self.mock_server.is_serving = MagicMock(return_value=False)
         self.assertIsNone(await self.session.listen())
         self.mock_reader.read.assert_not_awaited()
         mock__parse_command.assert_not_awaited()
+        self.mock_writer.write.assert_not_called()
         self.mock_writer.drain.assert_not_awaited()

tests/test_internals/test_helpers.py

@@ -19,7 +19,7 @@ Unittests for the `asyncio_taskpool.helpers` module.
 """
 
 
-from unittest import IsolatedAsyncioTestCase
+from unittest import IsolatedAsyncioTestCase, TestCase
 from unittest.mock import MagicMock, AsyncMock, NonCallableMagicMock, call, patch
 
 from asyncio_taskpool.internals import helpers
@@ -122,3 +122,33 @@ class HelpersTestCase(IsolatedAsyncioTestCase):
             with self.assertRaises(AttributeError):
                 helpers.resolve_dotted_path('foo.bar.baz')
             mock_import_module.assert_has_calls([call('foo'), call('foo.bar')])
+
+
+class ClassMethodWorkaroundTestCase(TestCase):
+    def test_init(self):
+        def func(): return 'foo'
+        def getter(): return 'bar'
+        prop = property(getter)
+        instance = helpers.ClassMethodWorkaround(func)
+        self.assertIs(func, instance._getter)
+        instance = helpers.ClassMethodWorkaround(prop)
+        self.assertIs(getter, instance._getter)
+
+    @patch.object(helpers.ClassMethodWorkaround, '__init__', return_value=None)
+    def test_get(self, _mock_init: MagicMock):
+        def func(x: MagicMock): return x.__name__
+        instance = helpers.ClassMethodWorkaround(MagicMock())
+        instance._getter = func
+        obj, cls = None, MagicMock
+        expected_output = 'MagicMock'
+        output = instance.__get__(obj, cls)
+        self.assertEqual(expected_output, output)
+
+        obj = MagicMock(__name__='bar')
+        expected_output = 'bar'
+        output = instance.__get__(obj, cls)
+        self.assertEqual(expected_output, output)
+
+        cls = None
+        output = instance.__get__(obj, cls)
+        self.assertEqual(expected_output, output)

tests/test_pool.py

@@ -455,49 +455,65 @@ class TaskPoolTestCase(CommonTestCase):
         self.assertEqual(expected_output, output)
 
     @patch.object(pool.TaskPool, '_start_task')
-    async def test__apply_num(self, mock__start_task: AsyncMock):
-        group_name = FOO + BAR
-        mock_awaitable = object()
-        mock_func = MagicMock(return_value=mock_awaitable)
-        args, kwargs, num = (FOO, BAR), {'a': 1, 'b': 2}, 3
+    async def test__apply_spawner(self, mock__start_task: AsyncMock):
+        grp_name = FOO + BAR
+        mock_awaitable1, mock_awaitable2 = object(), object()
+        mock_func = MagicMock(side_effect=[mock_awaitable1, Exception(), mock_awaitable2], __name__='func')
+        args, kw, num = (FOO, BAR), {'a': 1, 'b': 2}, 3
         end_cb, cancel_cb = MagicMock(), MagicMock()
-        self.assertIsNone(await self.task_pool._apply_num(group_name, mock_func, args, kwargs, num, end_cb, cancel_cb))
-        mock_func.assert_has_calls(3 * [call(*args, **kwargs)])
-        mock__start_task.assert_has_awaits(3 * [
-            call(mock_awaitable, group_name=group_name, end_callback=end_cb, cancel_callback=cancel_cb)
+        self.assertIsNone(await self.task_pool._apply_spawner(grp_name, mock_func, args, kw, num, end_cb, cancel_cb))
+        mock_func.assert_has_calls(num * [call(*args, **kw)])
+        mock__start_task.assert_has_awaits([
+            call(mock_awaitable1, group_name=grp_name, end_callback=end_cb, cancel_callback=cancel_cb),
+            call(mock_awaitable2, group_name=grp_name, end_callback=end_cb, cancel_callback=cancel_cb),
         ])
 
-        mock_func.reset_mock()
+        mock_func.reset_mock(side_effect=True)
         mock__start_task.reset_mock()
 
-        self.assertIsNone(await self.task_pool._apply_num(group_name, mock_func, args, None, num, end_cb, cancel_cb))
-        mock_func.assert_has_calls(num * [call(*args)])
-        mock__start_task.assert_has_awaits(num * [
-            call(mock_awaitable, group_name=group_name, end_callback=end_cb, cancel_callback=cancel_cb)
+        # Simulate cancellation while the second task is being started.
+        mock__start_task.side_effect = [None, CancelledError, None]
+        mock_coroutine_to_close = MagicMock()
+        mock_func.side_effect = [mock_awaitable1, mock_coroutine_to_close, 'never called']
+        self.assertIsNone(await self.task_pool._apply_spawner(grp_name, mock_func, args, None, num, end_cb, cancel_cb))
+        mock_func.assert_has_calls(2 * [call(*args)])
+        mock__start_task.assert_has_awaits([
+            call(mock_awaitable1, group_name=grp_name, end_callback=end_cb, cancel_callback=cancel_cb),
+            call(mock_coroutine_to_close, group_name=grp_name, end_callback=end_cb, cancel_callback=cancel_cb),
         ])
+        mock_coroutine_to_close.close.assert_called_once_with()
 
     @patch.object(pool, 'create_task')
-    @patch.object(pool.TaskPool, '_apply_num', new_callable=MagicMock())
+    @patch.object(pool.TaskPool, '_apply_spawner', new_callable=MagicMock())
     @patch.object(pool, 'TaskGroupRegister')
     @patch.object(pool.TaskPool, '_generate_group_name')
     @patch.object(pool.BaseTaskPool, '_check_start')
     def test_apply(self, mock__check_start: MagicMock, mock__generate_group_name: MagicMock,
-                   mock_reg_cls: MagicMock, mock__apply_num: MagicMock, mock_create_task: MagicMock):
+                   mock_reg_cls: MagicMock, mock__apply_spawner: MagicMock, mock_create_task: MagicMock):
         mock__generate_group_name.return_value = generated_name = 'name 123'
         mock_group_reg = set_up_mock_group_register(mock_reg_cls)
-        mock__apply_num.return_value = mock_apply_coroutine = object()
+        mock__apply_spawner.return_value = mock_apply_coroutine = object()
         mock_create_task.return_value = fake_task = object()
         mock_func, num, group_name = MagicMock(), 3, FOO + BAR
         args, kwargs = (FOO, BAR), {'a': 1, 'b': 2}
         end_cb, cancel_cb = MagicMock(), MagicMock()
+
+        self.task_pool._task_groups = {group_name: 'causes error'}
+        with self.assertRaises(exceptions.InvalidGroupName):
+            self.task_pool.apply(mock_func, args, kwargs, num, group_name, end_cb, cancel_cb)
+        mock__check_start.assert_called_once_with(function=mock_func)
+        mock__apply_spawner.assert_not_called()
+        mock_create_task.assert_not_called()
+
+        mock__check_start.reset_mock()
         self.task_pool._task_groups = {}
 
         def check_assertions(_group_name, _output):
             self.assertEqual(_group_name, _output)
             mock__check_start.assert_called_once_with(function=mock_func)
             self.assertEqual(mock_group_reg, self.task_pool._task_groups[_group_name])
-            mock__apply_num.assert_called_once_with(_group_name, mock_func, args, kwargs, num,
-                                                    end_callback=end_cb, cancel_callback=cancel_cb)
+            mock__apply_spawner.assert_called_once_with(_group_name, mock_func, args, kwargs, num,
+                                                        end_callback=end_cb, cancel_callback=cancel_cb)
             mock_create_task.assert_called_once_with(mock_apply_coroutine)
             self.assertSetEqual({fake_task}, self.task_pool._group_meta_tasks_running[group_name])
 
@@ -507,7 +523,7 @@ class TaskPoolTestCase(CommonTestCase):
 
         mock__check_start.reset_mock()
         self.task_pool._task_groups.clear()
-        mock__apply_num.reset_mock()
+        mock__apply_spawner.reset_mock()
         mock_create_task.reset_mock()
 
         output = self.task_pool.apply(mock_func, args, kwargs, num, None, end_cb, cancel_cb)
@@ -532,20 +548,20 @@ class TaskPoolTestCase(CommonTestCase):
         n = 2
         mock_semaphore_cls.return_value = semaphore = Semaphore(n)
         mock__get_map_end_callback.return_value = map_cb = MagicMock()
-        awaitable = 'totally an awaitable'
-        mock_star_function.side_effect = [awaitable, Exception(), awaitable]
+        awaitable1, awaitable2 = 'totally an awaitable', object()
+        mock_star_function.side_effect = [awaitable1, Exception(), awaitable2]
         arg1, arg2, bad = 123456789, 'function argument', None
         args = [arg1, bad, arg2]
-        group_name, mock_func, stars = 'whatever', MagicMock(__name__="mock"), 3
+        grp_name, mock_func, stars = 'whatever', MagicMock(__name__="mock"), 3
         end_cb, cancel_cb = MagicMock(), MagicMock()
-        self.assertIsNone(await self.task_pool._arg_consumer(group_name, n, mock_func, args, stars, end_cb, cancel_cb))
-        # We expect the semaphore to be acquired 2 times, then be released once after the exception occurs, then
-        # acquired once more is reached. Since we initialized it with a value of 2, we expect it be locked.
+        self.assertIsNone(await self.task_pool._arg_consumer(grp_name, n, mock_func, args, stars, end_cb, cancel_cb))
+        # We initialized the semaphore with a value of 2. It should have been acquired twice. We expect it be locked.
         self.assertTrue(semaphore.locked())
         mock_semaphore_cls.assert_called_once_with(n)
         mock__get_map_end_callback.assert_called_once_with(semaphore, actual_end_callback=end_cb)
-        mock__start_task.assert_has_awaits(2 * [
-            call(awaitable, group_name=group_name, ignore_lock=True, end_callback=map_cb, cancel_callback=cancel_cb)
+        mock__start_task.assert_has_awaits([
+            call(awaitable1, group_name=grp_name, ignore_lock=True, end_callback=map_cb, cancel_callback=cancel_cb),
+            call(awaitable2, group_name=grp_name, ignore_lock=True, end_callback=map_cb, cancel_callback=cancel_cb),
         ])
         mock_star_function.assert_has_calls([
             call(mock_func, arg1, arg_stars=stars),
@@ -556,17 +572,50 @@ class TaskPoolTestCase(CommonTestCase):
         mock_semaphore_cls.reset_mock()
         mock__get_map_end_callback.reset_mock()
         mock__start_task.reset_mock()
-        mock_star_function.reset_mock()
+        mock_star_function.reset_mock(side_effect=True)
 
-        # With a CancelledError thrown while starting a task:
-        mock_semaphore_cls.return_value = semaphore = Semaphore(1)
-        mock_star_function.side_effect = CancelledError()
-        self.assertIsNone(await self.task_pool._arg_consumer(group_name, n, mock_func, args, stars, end_cb, cancel_cb))
-        self.assertFalse(semaphore.locked())
+        # With a CancelledError thrown while acquiring the semaphore:
+        mock_acquire = AsyncMock(side_effect=[True, CancelledError])
+        mock_semaphore_cls.return_value = mock_semaphore = MagicMock(acquire=mock_acquire)
+        mock_star_function.return_value = mock_coroutine = MagicMock()
+        arg_it = iter(arg for arg in (arg1, arg2, FOO))
+        self.assertIsNone(await self.task_pool._arg_consumer(grp_name, n, mock_func, arg_it, stars, end_cb, cancel_cb))
         mock_semaphore_cls.assert_called_once_with(n)
-        mock__get_map_end_callback.assert_called_once_with(semaphore, actual_end_callback=end_cb)
-        mock__start_task.assert_not_called()
-        mock_star_function.assert_called_once_with(mock_func, arg1, arg_stars=stars)
+        mock__get_map_end_callback.assert_called_once_with(mock_semaphore, actual_end_callback=end_cb)
+        mock_star_function.assert_has_calls([
+            call(mock_func, arg1, arg_stars=stars),
+            call(mock_func, arg2, arg_stars=stars)
+        ])
+        mock_acquire.assert_has_awaits([call(), call()])
+        mock__start_task.assert_awaited_once_with(mock_coroutine, group_name=grp_name, ignore_lock=True,
+                                                  end_callback=map_cb, cancel_callback=cancel_cb)
+        mock_coroutine.close.assert_called_once_with()
+        mock_semaphore.release.assert_not_called()
+        self.assertEqual(FOO, next(arg_it))
+
+        mock_acquire.reset_mock(side_effect=True)
+        mock_semaphore_cls.reset_mock()
+        mock__get_map_end_callback.reset_mock()
+        mock__start_task.reset_mock()
+        mock_star_function.reset_mock(side_effect=True)
+
+        # With a CancelledError thrown while starting the task:
+        mock__start_task.side_effect = [None, CancelledError]
+        arg_it = iter(arg for arg in (arg1, arg2, FOO))
+        self.assertIsNone(await self.task_pool._arg_consumer(grp_name, n, mock_func, arg_it, stars, end_cb, cancel_cb))
+        mock_semaphore_cls.assert_called_once_with(n)
+        mock__get_map_end_callback.assert_called_once_with(mock_semaphore, actual_end_callback=end_cb)
+        mock_star_function.assert_has_calls([
+            call(mock_func, arg1, arg_stars=stars),
+            call(mock_func, arg2, arg_stars=stars)
+        ])
+        mock_acquire.assert_has_awaits([call(), call()])
+        mock__start_task.assert_has_awaits(2 * [
+            call(mock_coroutine, group_name=grp_name, ignore_lock=True, end_callback=map_cb, cancel_callback=cancel_cb)
+        ])
+        mock_coroutine.close.assert_called_once_with()
+        mock_semaphore.release.assert_called_once_with()
+        self.assertEqual(FOO, next(arg_it))
 
     @patch.object(pool, 'create_task')
     @patch.object(pool.TaskPool, '_arg_consumer', new_callable=MagicMock)
@@ -680,13 +729,15 @@ class SimpleTaskPoolTestCase(CommonTestCase):
     TEST_POOL_CANCEL_CB = MagicMock()
 
     def get_task_pool_init_params(self) -> dict:
-        return super().get_task_pool_init_params() | {
+        params = super().get_task_pool_init_params()
+        params.update({
             'func': self.TEST_POOL_FUNC,
             'args': self.TEST_POOL_ARGS,
             'kwargs': self.TEST_POOL_KWARGS,
             'end_callback': self.TEST_POOL_END_CB,
             'cancel_callback': self.TEST_POOL_CANCEL_CB,
-        }
+        })
+        return params
 
     def setUp(self) -> None:
         self.base_class_init_patcher = patch.object(pool.BaseTaskPool, '__init__')
@@ -695,6 +746,7 @@ class SimpleTaskPoolTestCase(CommonTestCase):
 
     def tearDown(self) -> None:
         self.base_class_init_patcher.stop()
+        super().tearDown()
 
     def test_init(self):
         self.assertEqual(self.TEST_POOL_FUNC, self.task_pool._func)