diff --git a/setup.cfg b/setup.cfg
index c0caba2..3be8096 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -1,6 +1,6 @@
 [metadata]
 name = asyncio-taskpool
-version = 0.3.3
+version = 0.3.4
 author = Daniil Fajnberg
 author_email = mail@daniil.fajnberg.de
 description = Dynamically manage pools of asyncio tasks
diff --git a/src/asyncio_taskpool/constants.py b/src/asyncio_taskpool/constants.py
index 19d56c7..c4f0869 100644
--- a/src/asyncio_taskpool/constants.py
+++ b/src/asyncio_taskpool/constants.py
@@ -24,7 +24,7 @@ PACKAGE_NAME = 'asyncio_taskpool'
 CLIENT_EXIT = 'exit'
 
 SESSION_MSG_BYTES = 1024 * 100
-SESSION_PARSER_WRITER = 'session_writer'
+SESSION_WRITER = 'session_writer'
 
 
 class CLIENT_INFO:
diff --git a/src/asyncio_taskpool/session.py b/src/asyncio_taskpool/session.py
index 6db1d01..2216076 100644
--- a/src/asyncio_taskpool/session.py
+++ b/src/asyncio_taskpool/session.py
@@ -25,7 +25,7 @@ from argparse import ArgumentError, HelpFormatter
 from asyncio.streams import StreamReader, StreamWriter
 from typing import Callable, Optional, Union, TYPE_CHECKING
 
-from .constants import CMD, SESSION_PARSER_WRITER, SESSION_MSG_BYTES, CLIENT_INFO
+from .constants import CMD, SESSION_WRITER, SESSION_MSG_BYTES, CLIENT_INFO
 from .exceptions import HelpRequested, NotATaskPool, UnknownTaskPoolClass
 from .helpers import get_first_doc_line, return_or_exception, tasks_str
 from .pool import BaseTaskPool, TaskPool, SimpleTaskPool
@@ -166,7 +166,7 @@ class ControlSession:
         """
         parser_kwargs = {
             'prog': '',
-            SESSION_PARSER_WRITER: self._writer,
+            SESSION_WRITER: self._writer,
             CLIENT_INFO.TERMINAL_WIDTH: client_terminal_width,
         }
         self._parser = CommandParser(**parser_kwargs)
diff --git a/src/asyncio_taskpool/session_parser.py b/src/asyncio_taskpool/session_parser.py
index a315234..d27e0cc 100644
--- a/src/asyncio_taskpool/session_parser.py
+++ b/src/asyncio_taskpool/session_parser.py
@@ -1,8 +1,29 @@
+__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__ = """
+This module contains the the definition of the `CommandParser` class used in a control server session.
+"""
+
+
 from argparse import Action, ArgumentParser, ArgumentDefaultsHelpFormatter, HelpFormatter
 from asyncio.streams import StreamWriter
 from typing import Type, TypeVar
 
-from .constants import SESSION_PARSER_WRITER, CLIENT_INFO
+from .constants import SESSION_WRITER, CLIENT_INFO
 from .exceptions import HelpRequested
 
 
@@ -12,8 +33,33 @@ NUM = 'num'
 
 
 class CommandParser(ArgumentParser):
+    """
+    Subclass of the standard `argparse.ArgumentParser` for remote interaction.
+
+    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.
+    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.
+    """
+
     @staticmethod
     def help_formatter_factory(terminal_width: int, base_cls: FmtCls = None) -> FmtCls:
+        """
+        Constructs and returns a subclass of `argparse.HelpFormatter` with a fixed terminal width argument.
+
+        Although a custom formatter class can be explicitly passed into the `ArgumentParser` constructor, this is not
+        as convenient, when making use of sub-parsers.
+
+        Args:
+            terminal_width:
+                The number of columns of the terminal to which to adjust help formatting.
+            base_cls (optional):
+                The base class to use for inheritance. By default `argparse.ArgumentDefaultsHelpFormatter` is used.
+
+        Returns:
+            The subclass of `base_cls` which fixes the constructor's `width` keyword-argument to `terminal_width`.
+        """
         if base_cls is None:
             base_cls = ArgumentDefaultsHelpFormatter
 
@@ -23,35 +69,56 @@ class CommandParser(ArgumentParser):
                 super().__init__(*args, **kwargs)
         return ClientHelpFormatter
 
-    def __init__(self, *args, **kwargs) -> None:
-        parent: CommandParser = kwargs.pop('parent', None)
-        self._stream_writer: StreamWriter = parent.stream_writer if parent else kwargs.pop(SESSION_PARSER_WRITER)
+    def __init__(self, parent: 'CommandParser' = None, **kwargs) -> None:
+        """
+        Sets additional internal attributes depending on whether a parent-parser was defined.
+
+        The `help_formatter_factory` is called and the returned class is mapped to the `FORMATTER_CLASS` keyword.
+        By default, `exit_on_error` is set to `False` (as opposed to how the parent class handles it).
+
+        Args:
+            parent (optional):
+                An instance of the same class. Intended to be passed as a keyword-argument into the `add_parser` method
+                of the subparsers action returned by the `ArgumentParser.add_subparsers` method. If this is present,
+                the `SESSION_WRITER` and `CLIENT_INFO.TERMINAL_WIDTH` keywords must not be present in `kwargs`.
+            **kwargs(optional):
+                In addition to the regular `ArgumentParser` constructor parameters, this method expects the instance of
+                the `StreamWriter` as well as the terminal width both to be passed explicitly, if the `parent` argument
+                is empty.
+        """
+        self._session_writer: StreamWriter = parent.session_writer if parent else kwargs.pop(SESSION_WRITER)
         self._terminal_width: int = parent.terminal_width if parent else kwargs.pop(CLIENT_INFO.TERMINAL_WIDTH)
         kwargs[FORMATTER_CLASS] = self.help_formatter_factory(self._terminal_width, kwargs.get(FORMATTER_CLASS))
         kwargs.setdefault('exit_on_error', False)
-        super().__init__(*args, **kwargs)
+        super().__init__(**kwargs)
 
     @property
-    def stream_writer(self) -> StreamWriter:
-        return self._stream_writer
+    def session_writer(self) -> StreamWriter:
+        """Returns the predefined stream writer object of the control session."""
+        return self._session_writer
 
     @property
     def terminal_width(self) -> int:
+        """Returns the predefined terminal width."""
         return self._terminal_width
 
     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."""
         if message:
-            self.stream_writer.write(message.encode())
+            self._session_writer.write(message.encode())
 
     def exit(self, status: int = 0, message: str = None) -> None:
+        """This is overridden to prevent system exit to be invoked."""
         if message:
             self._print_message(message)
 
     def print_help(self, file=None) -> None:
+        """This just adds the custom `HelpRequested` exception after the parent class' method."""
         super().print_help(file)
         raise HelpRequested
 
     def add_optional_num_argument(self, *name_or_flags: str, **kwargs) -> Action:
+        """Convenience method for `add_argument` setting the name, `nargs`, `default`, and `type`, unless specified."""
         if not name_or_flags:
             name_or_flags = (NUM, )
         kwargs.setdefault('nargs', '?')
diff --git a/tests/test_session.py b/tests/test_session.py
index 921e06d..2a3eb1d 100644
--- a/tests/test_session.py
+++ b/tests/test_session.py
@@ -25,7 +25,7 @@ from unittest import IsolatedAsyncioTestCase
 from unittest.mock import AsyncMock, MagicMock, patch, call
 
 from asyncio_taskpool import session
-from asyncio_taskpool.constants import CLIENT_INFO, CMD, SESSION_MSG_BYTES, SESSION_PARSER_WRITER
+from asyncio_taskpool.constants import CLIENT_INFO, CMD, SESSION_MSG_BYTES, SESSION_WRITER
 from asyncio_taskpool.exceptions import HelpRequested, NotATaskPool, UnknownTaskPoolClass
 from asyncio_taskpool.pool import BaseTaskPool, TaskPool, SimpleTaskPool
 
@@ -119,7 +119,7 @@ class ControlServerTestCase(IsolatedAsyncioTestCase):
         width = 1234
         expected_parser_kwargs = {
             'prog': '',
-            SESSION_PARSER_WRITER: self.mock_writer,
+            SESSION_WRITER: self.mock_writer,
             CLIENT_INFO.TERMINAL_WIDTH: width,
         }
         self.assertIsNone(self.session._init_parser(width))
diff --git a/tests/test_session_parser.py b/tests/test_session_parser.py
new file mode 100644
index 0000000..da7fff8
--- /dev/null
+++ b/tests/test_session_parser.py
@@ -0,0 +1,134 @@
+__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__ = """
+Unittests for the `asyncio_taskpool.session_parser` module.
+"""
+
+
+from argparse import Action, ArgumentParser, HelpFormatter, ArgumentDefaultsHelpFormatter, RawTextHelpFormatter
+from unittest import IsolatedAsyncioTestCase
+from unittest.mock import MagicMock, patch
+
+from asyncio_taskpool import session_parser
+from asyncio_taskpool.constants import SESSION_WRITER, CLIENT_INFO
+from asyncio_taskpool.exceptions import HelpRequested
+
+
+FOO = 'foo'
+
+
+class ControlServerTestCase(IsolatedAsyncioTestCase):
+
+    def setUp(self) -> None:
+        self.help_formatter_factory_patcher = patch.object(session_parser.CommandParser, 'help_formatter_factory')
+        self.mock_help_formatter_factory = self.help_formatter_factory_patcher.start()
+        self.mock_help_formatter_factory.return_value = RawTextHelpFormatter
+        self.session_writer, self.terminal_width = MagicMock(), 420
+        self.kwargs = {
+            SESSION_WRITER: self.session_writer,
+            CLIENT_INFO.TERMINAL_WIDTH: self.terminal_width,
+            session_parser.FORMATTER_CLASS: FOO
+        }
+        self.parser = session_parser.CommandParser(**self.kwargs)
+
+    def tearDown(self) -> None:
+        self.help_formatter_factory_patcher.stop()
+
+    def test_help_formatter_factory(self):
+        self.help_formatter_factory_patcher.stop()
+
+        class MockBaseClass(HelpFormatter):
+            def __init__(self, *args, **kwargs):
+                super().__init__(*args, **kwargs)
+
+        terminal_width = 123456789
+        cls = session_parser.CommandParser.help_formatter_factory(terminal_width, MockBaseClass)
+        self.assertTrue(issubclass(cls, MockBaseClass))
+        instance = cls('prog')
+        self.assertEqual(terminal_width, getattr(instance, '_width'))
+
+        cls = session_parser.CommandParser.help_formatter_factory(terminal_width)
+        self.assertTrue(issubclass(cls, ArgumentDefaultsHelpFormatter))
+        instance = cls('prog')
+        self.assertEqual(terminal_width, getattr(instance, '_width'))
+
+    def test_init(self):
+        self.assertIsInstance(self.parser, ArgumentParser)
+        self.assertEqual(self.session_writer, self.parser._session_writer)
+        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'))
+
+    def test_session_writer(self):
+        self.assertEqual(self.session_writer, self.parser.session_writer)
+
+    def test_terminal_width(self):
+        self.assertEqual(self.terminal_width, self.parser.terminal_width)
+
+    def test__print_message(self):
+        self.session_writer.write = MagicMock()
+        self.assertIsNone(self.parser._print_message(''))
+        self.session_writer.write.assert_not_called()
+        msg = 'foo bar baz'
+        self.assertIsNone(self.parser._print_message(msg))
+        self.session_writer.write.assert_called_once_with(msg.encode())
+
+    @patch.object(session_parser.CommandParser, '_print_message')
+    def test_exit(self, mock__print_message: MagicMock):
+        self.assertIsNone(self.parser.exit(123, ''))
+        mock__print_message.assert_not_called()
+        msg = 'foo bar baz'
+        self.assertIsNone(self.parser.exit(123, msg))
+        mock__print_message.assert_called_once_with(msg)
+
+    @patch.object(session_parser.ArgumentParser, 'print_help')
+    def test_print_help(self, mock_print_help: MagicMock):
+        arg = MagicMock()
+        with self.assertRaises(HelpRequested):
+            self.parser.print_help(arg)
+        mock_print_help.assert_called_once_with(arg)
+
+    def test_add_optional_num_argument(self):
+        metavar = 'FOOBAR'
+        action = self.parser.add_optional_num_argument(metavar=metavar)
+        self.assertIsInstance(action, Action)
+        self.assertEqual('?', action.nargs)
+        self.assertEqual(1, action.default)
+        self.assertEqual(int, action.type)
+        self.assertEqual(metavar, action.metavar)
+        num = 111
+        kwargs = vars(self.parser.parse_args([f'{num}']))
+        self.assertDictEqual({session_parser.NUM: num}, kwargs)
+
+        name = f'--{FOO}'
+        nargs = '+'
+        default = 1
+        _type = float
+        required = True
+        dest = 'foo_bar'
+        action = self.parser.add_optional_num_argument(name, nargs=nargs, default=default, type=_type,
+                                                       required=required, metavar=metavar, dest=dest)
+        self.assertIsInstance(action, Action)
+        self.assertEqual(nargs, action.nargs)
+        self.assertEqual(default, action.default)
+        self.assertEqual(_type, action.type)
+        self.assertEqual(required, action.required)
+        self.assertEqual(metavar, action.metavar)
+        self.assertEqual(dest, action.dest)
+        kwargs = vars(self.parser.parse_args([f'{num}', name, '1', '1.5']))
+        self.assertDictEqual({session_parser.NUM: num, dest: [1.0, 1.5]}, kwargs)