From 1ce21d16e2690f019c92e611e8656e61ec9dbee1 Mon Sep 17 00:00:00 2001
From: Kazuaki Matsuo <fly.49.89.over@gmail.com>
Date: Tue, 22 Jun 2021 01:39:20 -0700
Subject: [PATCH 01/12] chore: add placeholder

---
 appium/webdriver/webdriver.py | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/appium/webdriver/webdriver.py b/appium/webdriver/webdriver.py
index 393684841..d20b57db8 100644
--- a/appium/webdriver/webdriver.py
+++ b/appium/webdriver/webdriver.py
@@ -151,6 +151,7 @@ def __init__(
         proxy: str = None,
         keep_alive: bool = True,
         direct_connection: bool = False,
+        extensions: List[str] = [],
     ):
 
         super().__init__(
@@ -176,6 +177,10 @@ def __init__(
         By.IMAGE = MobileBy.IMAGE
         By.CUSTOM = MobileBy.CUSTOM
 
+        for extention in extensions:
+            # TODO: add new methods
+            pass
+
     def _update_command_executor(self, keep_alive: bool) -> None:
         """Update command executor following directConnect feature"""
         direct_protocol = 'directConnectProtocol'

From 69df40f48c337b8954899e2ea89d4669320bc81e Mon Sep 17 00:00:00 2001
From: Kazuaki Matsuo <fly.49.89.over@gmail.com>
Date: Wed, 23 Jun 2021 00:07:07 -0700
Subject: [PATCH 02/12] move to extention way

---
 appium/webdriver/webdriver.py         | 123 ++++++--------------------
 test/pytest.ini                       |   2 +-
 test/unit/helper/test_helper.py       |  34 +++++++
 test/unit/webdriver/webdriver_test.py |  83 +++++++++--------
 4 files changed, 109 insertions(+), 133 deletions(-)

diff --git a/appium/webdriver/webdriver.py b/appium/webdriver/webdriver.py
index d20b57db8..60df447d6 100644
--- a/appium/webdriver/webdriver.py
+++ b/appium/webdriver/webdriver.py
@@ -15,7 +15,7 @@
 # pylint: disable=too-many-lines,too-many-public-methods,too-many-statements,no-self-use
 
 import copy
-from typing import Any, Dict, List, Optional, TypeVar, Union
+from typing import Any, Callable, Dict, List, Optional, Tuple, TypeVar, Union
 
 from selenium.common.exceptions import InvalidArgumentException
 from selenium.webdriver.common.by import By
@@ -114,6 +114,23 @@ def _make_w3c_caps(caps: Dict) -> Dict[str, List[Dict[str, Any]]]:
 T = TypeVar('T', bound='WebDriver')
 
 
+class ExtensionBase:
+    def __init__(self, execute: Callable):
+        self._execute = execute
+
+    def execute(self, parameters: Any) -> Any:
+        return self._execute(self.method_name(), parameters)
+
+    def method_name(self) -> str:
+        raise NotImplementedError('Please define a method name')
+
+    def command_wrapper(self) -> None:
+        raise NotImplementedError('Please define exact call')
+
+    def custom_command(self) -> Tuple[str, str]:
+        raise NotImplementedError('Please define exact call')
+
+
 class WebDriver(
     AppiumSearchContext,
     ActionHelpers,
@@ -151,7 +168,7 @@ def __init__(
         proxy: str = None,
         keep_alive: bool = True,
         direct_connection: bool = False,
-        extensions: List[str] = [],
+        extensions: List[T] = [],
     ):
 
         super().__init__(
@@ -177,9 +194,15 @@ def __init__(
         By.IMAGE = MobileBy.IMAGE
         By.CUSTOM = MobileBy.CUSTOM
 
-        for extention in extensions:
-            # TODO: add new methods
-            pass
+        for extension in extensions:
+            instance = extension(self.execute)
+            if hasattr(WebDriver, instance.method_name()):
+                logger.warn(
+                    '{} is alreadt defined. The new one is overriding the old one.'.format(instance.method_name())
+                )
+            setattr(WebDriver, instance.method_name(), instance.command_wrapper)
+            method, url_cmd = instance.custom_command()
+            self.command_executor._commands[instance.method_name()] = (method.upper(), url_cmd)  # type: ignore
 
     def _update_command_executor(self, keep_alive: bool) -> None:
         """Update command executor following directConnect feature"""
@@ -362,96 +385,6 @@ def switch_to(self) -> MobileSwitchTo:
 
         return MobileSwitchTo(self)
 
-    def add_command(self, method: CommandMethod, url: str, name: str) -> T:
-        """Add a custom command as 'name'
-
-        Args:
-            method: The method of HTTP request. Available methods are CommandMethod.
-            url: The url is URL template as https://www.w3.org/TR/webdriver/#endpoints.
-                 `$sessionId` is a placeholder of current session id.
-                 Other placeholders can be specified with `$` prefix like `$id`.
-                 Then, `{'id': 'some id'}` argument in `execute_custom_command` replaces
-                 the `$id` with the value, `some id`, in the request.
-            name: The name of a command to call in `execute_custom_command`.
-
-        Returns:
-            `appium.webdriver.webdriver.WebDriver`: Self instance
-
-        Raises:
-            ValueError
-
-        Examples:
-            Define 'test_command' as GET and 'session/$sessionId/path/to/custom/url'
-
-            >>> from appium.webdriver.command_method import CommandMethod
-            >>> driver.add_command(
-                    method=CommandMethod.GET,
-                    url='session/$sessionId/path/to/custom/url',
-                    name='test_command'
-                )
-
-        """
-        if name in self.command_executor._commands:
-            raise ValueError("{} is already defined".format(name))
-
-        if not isinstance(method, CommandMethod):
-            raise ValueError(
-                "'{}' is invalid. Valid method should be one of '{}'.".format(method, CommandMethod.__name__)
-            )
-
-        self.command_executor._commands[name] = (method.value, url)
-        return self
-
-    def execute_custom_command(self, name: str, args: Dict = {}) -> Any:
-        """Execute a custom command defined as 'name' with args command.
-
-        Args:
-            name: The name of command defined by `add_command`.
-            args: The argument as this command body
-
-        Returns:
-            'value' JSON object field in the response body.
-
-        Raises:
-            ValueError, selenium.common.exceptions.WebDriverException
-
-        Examples:
-            Calls 'test_command' command without arguments.
-
-            >>> from appium.webdriver.command_method import CommandMethod
-            >>> driver.add_command(
-                    method=CommandMethod.GET,
-                    url='session/$sessionId/path/to/custom/url',
-                    name='test_command'
-                )
-            >>> result = driver.execute_custom_command('test_command')
-
-            Calls 'test_command' command with arguments.
-
-            >>> from appium.webdriver.command_method import CommandMethod
-            >>> driver.add_command(
-                    method=CommandMethod.POST,
-                    url='session/$sessionId/path/to/custom/url',
-                    name='test_command'
-                )
-            >>> result = driver.execute_custom_command('test_command', {'dummy': 'test argument'})
-
-            Calls 'test_command' command with arguments, and the path has 'element id'.
-            The '$id' will be 'element id' by 'id' key in the given argument.
-
-            >>> from appium.webdriver.command_method import CommandMethod
-            >>> driver.add_command(
-                    method=CommandMethod.POST,
-                    url='session/$sessionId/path/to/$id/url',
-                    name='test_command'
-                )
-            >>> result = driver.execute_custom_command('test_command', {'id': 'element id', 'dummy': 'test argument'})
-
-        """
-        if name not in self.command_executor._commands:
-            raise ValueError("No {} custom command. Please add it by 'add_command'".format(name))
-        return self.execute(name, args)['value']
-
     # pylint: disable=protected-access
 
     def _addCommands(self) -> None:
diff --git a/test/pytest.ini b/test/pytest.ini
index 0c95eb57c..12cc5a459 100644
--- a/test/pytest.ini
+++ b/test/pytest.ini
@@ -1,2 +1,2 @@
 [pytest]
-addopts = -ra -q --cov=appium
+
diff --git a/test/unit/helper/test_helper.py b/test/unit/helper/test_helper.py
index 44f8fbb96..9766e1b76 100644
--- a/test/unit/helper/test_helper.py
+++ b/test/unit/helper/test_helper.py
@@ -119,6 +119,40 @@ def ios_w3c_driver() -> 'WebDriver':
     return driver
 
 
+def ios_w3c_driver_with_extensions(extensions) -> 'WebDriver':
+    """Return a W3C driver which is generated by a mock response for iOS
+
+    Returns:
+        `webdriver.webdriver.WebDriver`: An instance of WebDriver
+    """
+
+    response_body_json = json.dumps(
+        {
+            'value': {
+                'sessionId': '1234567890',
+                'capabilities': {
+                    'device': 'iphone',
+                    'browserName': 'UICatalog',
+                    'sdkVersion': '11.4',
+                    'CFBundleIdentifier': 'com.example.apple-samplecode.UICatalog',
+                },
+            }
+        }
+    )
+
+    httpretty.register_uri(httpretty.POST, appium_command('/session'), body=response_body_json)
+
+    desired_caps = {
+        'platformName': 'iOS',
+        'deviceName': 'iPhone Simulator',
+        'app': 'path/to/app',
+        'automationName': 'XCUITest',
+    }
+
+    driver = webdriver.Remote(SERVER_URL_BASE, desired_caps, extensions=extensions)
+    return driver
+
+
 def get_httpretty_request_body(request: 'HTTPrettyRequestEmpty') -> Dict[str, Any]:
     """Returns utf-8 decoded request body"""
     return json.loads(request.body.decode('utf-8'))
diff --git a/test/unit/webdriver/webdriver_test.py b/test/unit/webdriver/webdriver_test.py
index df7d5e88f..9c2bccff8 100644
--- a/test/unit/webdriver/webdriver_test.py
+++ b/test/unit/webdriver/webdriver_test.py
@@ -21,8 +21,14 @@
 from appium import version as appium_version
 from appium import webdriver
 from appium.webdriver.command_method import CommandMethod
-from appium.webdriver.webdriver import WebDriver
-from test.unit.helper.test_helper import android_w3c_driver, appium_command, get_httpretty_request_body, ios_w3c_driver
+from appium.webdriver.webdriver import ExtensionBase, WebDriver
+from test.unit.helper.test_helper import (
+    android_w3c_driver,
+    appium_command,
+    get_httpretty_request_body,
+    ios_w3c_driver,
+    ios_w3c_driver_with_extensions,
+)
 
 
 class TestWebDriverWebDriver(object):
@@ -254,70 +260,73 @@ def exceptionCallback(request, uri, headers):
 
     @httpretty.activate
     def test_add_command(self):
-        driver = ios_w3c_driver()
+        class CustomURLCommand(ExtensionBase):
+            def method_name(self):
+                return 'test_command'
+
+            def command_wrapper(self):
+                return self.execute({})['value']
+
+            def custom_command(self):
+                return ('get', 'session/$sessionId/path/to/custom/url')
+
+        driver = ios_w3c_driver_with_extensions([CustomURLCommand])
         httpretty.register_uri(
             httpretty.GET,
             appium_command('session/1234567890/path/to/custom/url'),
             body=json.dumps({'value': {}}),
         )
-        driver.add_command(method=CommandMethod.GET, url='session/$sessionId/path/to/custom/url', name='test_command')
-        result = driver.execute_custom_command('test_command')
+        result = driver.test_command()
 
         assert result == {}
 
     @httpretty.activate
     def test_add_command_body(self):
-        driver = ios_w3c_driver()
+        class CustomURLCommand(ExtensionBase):
+            def method_name(self):
+                return 'test_command'
+
+            def command_wrapper(self, argument):
+                return self.execute(argument)['value']
+
+            def custom_command(self):
+                return ('post', 'session/$sessionId/path/to/custom/url')
+
+        driver = ios_w3c_driver_with_extensions([CustomURLCommand])
         httpretty.register_uri(
             httpretty.POST,
             appium_command('session/1234567890/path/to/custom/url'),
             body=json.dumps({'value': {}}),
         )
-        driver.add_command(method=CommandMethod.POST, url='session/$sessionId/path/to/custom/url', name='test_command')
-        result = driver.execute_custom_command('test_command', {'dummy': 'test argument'})
+        result = driver.test_command({'dummy': 'test argument'})
         assert result == {}
 
+        print(httpretty.last_request())
         d = get_httpretty_request_body(httpretty.last_request())
+
         assert d['dummy'] == 'test argument'
 
     @httpretty.activate
     def test_add_command_with_element_id(self):
-        driver = ios_w3c_driver()
+        class CustomURLCommand(ExtensionBase):
+            def method_name(self):
+                return 'test_command'
+
+            def command_wrapper(self, element_id):
+                return self.execute({'id': element_id})['value']
+
+            def custom_command(self):
+                return ('GET', 'session/$sessionId/path/to/custom/$id/url')
+
+        driver = ios_w3c_driver_with_extensions([CustomURLCommand])
         httpretty.register_uri(
             httpretty.GET,
             appium_command('session/1234567890/path/to/custom/element_id/url'),
             body=json.dumps({'value': {}}),
         )
-        driver.add_command(
-            method=CommandMethod.GET, url='session/$sessionId/path/to/custom/$id/url', name='test_command'
-        )
-        result = driver.execute_custom_command('test_command', {'id': 'element_id'})
+        result = driver.test_command('element_id')
         assert result == {}
 
-    @httpretty.activate
-    def test_add_command_already_defined(self):
-        driver = ios_w3c_driver()
-        driver.add_command(method=CommandMethod.GET, url='session/$sessionId/path/to/custom/url', name='test_command')
-        with pytest.raises(ValueError):
-            driver.add_command(
-                method=CommandMethod.GET, url='session/$sessionId/path/to/custom/url', name='test_command'
-            )
-
-    @httpretty.activate
-    def test_execute_custom_command(self):
-        driver = ios_w3c_driver()
-        driver.add_command(method=CommandMethod.GET, url='session/$sessionId/path/to/custom/url', name='test_command')
-        with pytest.raises(ValueError):
-            driver.add_command(
-                method=CommandMethod.GET, url='session/$sessionId/path/to/custom/url', name='test_command'
-            )
-
-    @httpretty.activate
-    def test_invalid_method(self):
-        driver = ios_w3c_driver()
-        with pytest.raises(ValueError):
-            driver.add_command(method='error', url='session/$sessionId/path/to/custom/url', name='test_command')
-
 
 class SubWebDriver(WebDriver):
     def __init__(self, command_executor, desired_capabilities, direct_connection=False):

From db70cf0ac29467feead708d0d327d5ebe7b2d269 Mon Sep 17 00:00:00 2001
From: Kazuaki Matsuo <fly.49.89.over@gmail.com>
Date: Wed, 23 Jun 2021 00:08:20 -0700
Subject: [PATCH 03/12] revert pytest

---
 test/pytest.ini | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/pytest.ini b/test/pytest.ini
index 12cc5a459..0c95eb57c 100644
--- a/test/pytest.ini
+++ b/test/pytest.ini
@@ -1,2 +1,2 @@
 [pytest]
-
+addopts = -ra -q --cov=appium

From 2731aaee2b315a337b4203651b6966df5087723f Mon Sep 17 00:00:00 2001
From: Kazuaki Matsuo <fly.49.89.over@gmail.com>
Date: Wed, 23 Jun 2021 00:47:03 -0700
Subject: [PATCH 04/12] add todo

---
 appium/webdriver/webdriver.py | 28 ++++++++++++++++++++++++----
 1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/appium/webdriver/webdriver.py b/appium/webdriver/webdriver.py
index 60df447d6..36c3168e4 100644
--- a/appium/webdriver/webdriver.py
+++ b/appium/webdriver/webdriver.py
@@ -115,6 +115,13 @@ def _make_w3c_caps(caps: Dict) -> Dict[str, List[Dict[str, Any]]]:
 
 
 class ExtensionBase:
+    """
+    Used to define an extension command.
+
+    TODO:
+    add examples
+    """
+
     def __init__(self, execute: Callable):
         self._execute = execute
 
@@ -122,13 +129,26 @@ def execute(self, parameters: Any) -> Any:
         return self._execute(self.method_name(), parameters)
 
     def method_name(self) -> str:
-        raise NotImplementedError('Please define a method name')
+        """
+        Expected to return a method name.
+        This name will be able to call as a driver method.
+
+        Returns:
+            'str' The method name.
+        """
+        raise NotImplementedError()
 
-    def command_wrapper(self) -> None:
-        raise NotImplementedError('Please define exact call')
+    def command_wrapper(self) -> Any:
+        """
+        Expected to do the actual command as `method_name`.
+        """
+        raise NotImplementedError()
 
     def custom_command(self) -> Tuple[str, str]:
-        raise NotImplementedError('Please define exact call')
+        """
+        Expected to define the pair of HTTP method and its URL.
+        """
+        raise NotImplementedError()
 
 
 class WebDriver(

From 18a9b6d30355bef9c0502174a458eef11ed0b104 Mon Sep 17 00:00:00 2001
From: Kazuaki Matsuo <fly.49.89.over@gmail.com>
Date: Sat, 3 Jul 2021 13:33:02 -0700
Subject: [PATCH 05/12] call method_name instead of wrapper

---
 appium/webdriver/webdriver.py         | 29 +++++++++++++++------------
 test/unit/webdriver/webdriver_test.py | 12 ++++++-----
 2 files changed, 23 insertions(+), 18 deletions(-)

diff --git a/appium/webdriver/webdriver.py b/appium/webdriver/webdriver.py
index 36c3168e4..e76bd7300 100644
--- a/appium/webdriver/webdriver.py
+++ b/appium/webdriver/webdriver.py
@@ -15,6 +15,7 @@
 # pylint: disable=too-many-lines,too-many-public-methods,too-many-statements,no-self-use
 
 import copy
+import types
 from typing import Any, Callable, Dict, List, Optional, Tuple, TypeVar, Union
 
 from selenium.common.exceptions import InvalidArgumentException
@@ -125,25 +126,19 @@ class ExtensionBase:
     def __init__(self, execute: Callable):
         self._execute = execute
 
-    def execute(self, parameters: Any) -> Any:
+    def execute(self, parameters: Any = {}) -> Any:
         return self._execute(self.method_name(), parameters)
 
     def method_name(self) -> str:
         """
         Expected to return a method name.
-        This name will be able to call as a driver method.
+        This name will be available as a driver method.
 
         Returns:
             'str' The method name.
         """
         raise NotImplementedError()
 
-    def command_wrapper(self) -> Any:
-        """
-        Expected to do the actual command as `method_name`.
-        """
-        raise NotImplementedError()
-
     def custom_command(self) -> Tuple[str, str]:
         """
         Expected to define the pair of HTTP method and its URL.
@@ -214,16 +209,24 @@ def __init__(
         By.IMAGE = MobileBy.IMAGE
         By.CUSTOM = MobileBy.CUSTOM
 
-        for extension in extensions:
+        self._extensions = extensions
+        for extension in self._extensions:
             instance = extension(self.execute)
             if hasattr(WebDriver, instance.method_name()):
-                logger.warn(
-                    '{} is alreadt defined. The new one is overriding the old one.'.format(instance.method_name())
-                )
-            setattr(WebDriver, instance.method_name(), instance.command_wrapper)
+                raise ValueError(f'{instance.method_name()} is already defined.')
+
+            # add a new method named 'instance.method_name()' and call it
+            setattr(WebDriver, instance.method_name(), getattr(instance, instance.method_name()))
             method, url_cmd = instance.custom_command()
             self.command_executor._commands[instance.method_name()] = (method.upper(), url_cmd)  # type: ignore
 
+    def delete_extensions(self) -> None:
+        """Delete extensions added in the class with 'setattr'"""
+        for extension in self._extensions:
+            instance = extension(self.execute)
+            if hasattr(WebDriver, instance.method_name()):
+                delattr(WebDriver, instance.method_name())
+
     def _update_command_executor(self, keep_alive: bool) -> None:
         """Update command executor following directConnect feature"""
         direct_protocol = 'directConnectProtocol'
diff --git a/test/unit/webdriver/webdriver_test.py b/test/unit/webdriver/webdriver_test.py
index 9c2bccff8..98cb3f3e8 100644
--- a/test/unit/webdriver/webdriver_test.py
+++ b/test/unit/webdriver/webdriver_test.py
@@ -264,8 +264,8 @@ class CustomURLCommand(ExtensionBase):
             def method_name(self):
                 return 'test_command'
 
-            def command_wrapper(self):
-                return self.execute({})['value']
+            def test_command(self):
+                return self.execute()['value']
 
             def custom_command(self):
                 return ('get', 'session/$sessionId/path/to/custom/url')
@@ -279,6 +279,7 @@ def custom_command(self):
         result = driver.test_command()
 
         assert result == {}
+        driver.delete_extensions()
 
     @httpretty.activate
     def test_add_command_body(self):
@@ -286,7 +287,7 @@ class CustomURLCommand(ExtensionBase):
             def method_name(self):
                 return 'test_command'
 
-            def command_wrapper(self, argument):
+            def test_command(self, argument):
                 return self.execute(argument)['value']
 
             def custom_command(self):
@@ -301,10 +302,10 @@ def custom_command(self):
         result = driver.test_command({'dummy': 'test argument'})
         assert result == {}
 
-        print(httpretty.last_request())
         d = get_httpretty_request_body(httpretty.last_request())
 
         assert d['dummy'] == 'test argument'
+        driver.delete_extensions()
 
     @httpretty.activate
     def test_add_command_with_element_id(self):
@@ -312,7 +313,7 @@ class CustomURLCommand(ExtensionBase):
             def method_name(self):
                 return 'test_command'
 
-            def command_wrapper(self, element_id):
+            def test_command(self, element_id):
                 return self.execute({'id': element_id})['value']
 
             def custom_command(self):
@@ -326,6 +327,7 @@ def custom_command(self):
         )
         result = driver.test_command('element_id')
         assert result == {}
+        driver.delete_extensions()
 
 
 class SubWebDriver(WebDriver):

From 14df3c62729f302a6736a003b12d6e50121a42ee Mon Sep 17 00:00:00 2001
From: Kazuaki Matsuo <fly.49.89.over@gmail.com>
Date: Sat, 3 Jul 2021 13:33:37 -0700
Subject: [PATCH 06/12] remove types

---
 appium/webdriver/webdriver.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/appium/webdriver/webdriver.py b/appium/webdriver/webdriver.py
index e76bd7300..65ce237c5 100644
--- a/appium/webdriver/webdriver.py
+++ b/appium/webdriver/webdriver.py
@@ -15,7 +15,6 @@
 # pylint: disable=too-many-lines,too-many-public-methods,too-many-statements,no-self-use
 
 import copy
-import types
 from typing import Any, Callable, Dict, List, Optional, Tuple, TypeVar, Union
 
 from selenium.common.exceptions import InvalidArgumentException

From 675c0533d65b8045e5d91789ded8b643f52105cf Mon Sep 17 00:00:00 2001
From: Kazuaki Matsuo <fly.49.89.over@gmail.com>
Date: Sun, 4 Jul 2021 10:00:36 -0700
Subject: [PATCH 07/12] rename a method

---
 appium/webdriver/webdriver.py         | 4 ++--
 test/unit/webdriver/webdriver_test.py | 6 +++---
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/appium/webdriver/webdriver.py b/appium/webdriver/webdriver.py
index 65ce237c5..9c8dadc6d 100644
--- a/appium/webdriver/webdriver.py
+++ b/appium/webdriver/webdriver.py
@@ -138,7 +138,7 @@ def method_name(self) -> str:
         """
         raise NotImplementedError()
 
-    def custom_command(self) -> Tuple[str, str]:
+    def add_command(self) -> Tuple[str, str]:
         """
         Expected to define the pair of HTTP method and its URL.
         """
@@ -216,7 +216,7 @@ def __init__(
 
             # add a new method named 'instance.method_name()' and call it
             setattr(WebDriver, instance.method_name(), getattr(instance, instance.method_name()))
-            method, url_cmd = instance.custom_command()
+            method, url_cmd = instance.add_command()
             self.command_executor._commands[instance.method_name()] = (method.upper(), url_cmd)  # type: ignore
 
     def delete_extensions(self) -> None:
diff --git a/test/unit/webdriver/webdriver_test.py b/test/unit/webdriver/webdriver_test.py
index 98cb3f3e8..d9cfea29b 100644
--- a/test/unit/webdriver/webdriver_test.py
+++ b/test/unit/webdriver/webdriver_test.py
@@ -267,7 +267,7 @@ def method_name(self):
             def test_command(self):
                 return self.execute()['value']
 
-            def custom_command(self):
+            def add_command(self):
                 return ('get', 'session/$sessionId/path/to/custom/url')
 
         driver = ios_w3c_driver_with_extensions([CustomURLCommand])
@@ -290,7 +290,7 @@ def method_name(self):
             def test_command(self, argument):
                 return self.execute(argument)['value']
 
-            def custom_command(self):
+            def add_command(self):
                 return ('post', 'session/$sessionId/path/to/custom/url')
 
         driver = ios_w3c_driver_with_extensions([CustomURLCommand])
@@ -316,7 +316,7 @@ def method_name(self):
             def test_command(self, element_id):
                 return self.execute({'id': element_id})['value']
 
-            def custom_command(self):
+            def add_command(self):
                 return ('GET', 'session/$sessionId/path/to/custom/$id/url')
 
         driver = ios_w3c_driver_with_extensions([CustomURLCommand])

From 0a42bd5d52a992ca2a72559edfef74b13d395de8 Mon Sep 17 00:00:00 2001
From: Kazuaki Matsuo <fly.49.89.over@gmail.com>
Date: Mon, 5 Jul 2021 11:19:41 -0700
Subject: [PATCH 08/12] add examples

---
 README.md                     |  3 +-
 appium/webdriver/webdriver.py | 78 +++++++++++++++++++++++++++++++++--
 2 files changed, 76 insertions(+), 5 deletions(-)

diff --git a/README.md b/README.md
index dde691c0a..0b2f8d1bd 100644
--- a/README.md
+++ b/README.md
@@ -135,7 +135,8 @@ self.driver = webdriver.Remote('http://localhost:4723/wd/hub', desired_caps, dir
 
 ## Documentation
 
-https://appium.github.io/python-client-sphinx/ is detailed documentation
+- https://appium.github.io/python-client-sphinx/ is detailed documentation
+- [functional tests](test/functional) also may help to see concrete examples.
 
 ## Development
 
diff --git a/appium/webdriver/webdriver.py b/appium/webdriver/webdriver.py
index 9c8dadc6d..5ea9a99e8 100644
--- a/appium/webdriver/webdriver.py
+++ b/appium/webdriver/webdriver.py
@@ -116,13 +116,83 @@ def _make_w3c_caps(caps: Dict) -> Dict[str, List[Dict[str, Any]]]:
 
 class ExtensionBase:
     """
-    Used to define an extension command.
+    Used to define an extension command as driver's methods.
 
-    TODO:
-    add examples
+    Example:
+        When you want to add `example_command` which calls a get request to
+        `session/$sessionId/path/to/your/custom/url`.
+
+        1. Defines an extension as a subclass of `ExtensionBase`
+            class CustomYourCommand(ExtensionBase):
+                def method_name(self):
+                    return 'custom_method_name'
+
+                # Define a method with the name of `method_name`
+                def custom_method_name(self):
+                    # Generally the response of Appium follows `{ 'value': { data } }`
+                    # format.
+                    return self.execute()['value']
+
+                # Used to register the command pair as "Appium command" in this driver.
+                def add_command(self):
+                    return ('GET', 'session/$sessionId/path/to/your/custom/url')
+
+        2. Creates a session with the extension.
+            # Appium capabilities
+            desired_caps = { ... }
+            driver = webdriver.Remote('http://localhost:4723/wd/hub', desired_caps,
+                extensions=[CustomYourCommand])
+
+        3. Calls the custom command
+            # Then, the driver calls a get request against
+            # `session/$sessionId/path/to/your/custom/url`. `$sessionId` will be
+            # replaced properly in the driver. Then, the method returns
+            # the `value` part of the response.
+            driver.custom_method_name()
+
+
+        You can give arbitrary arguments for the command like the below.
+
+            class CustomYourCommand(ExtensionBase):
+                def method_name(self):
+                    return 'custom_method_name'
+
+                def test_command(self, argument):
+                    return self.execute(argument)['value']
+
+                def add_command(self):
+                    return ('post', 'session/$sessionId/path/to/your/custom/url')
+
+            driver = webdriver.Remote('http://localhost:4723/wd/hub', desired_caps,
+                extensions=[CustomYourCommand])
+
+            # Then, the driver sends a post request to `session/$sessionId/path/to/your/custom/url`
+            # with `{'dummy_arg': 'as a value'}` JSON body.
+            driver.custom_method_name({'dummy_arg': 'as a value'})
+
+
+        When you customize the URL dinamically with element id.
+
+            class CustomURLCommand(ExtensionBase):
+                def method_name(self):
+                    return 'custom_method_name'
+
+                def custom_method_name(self, element_id):
+                    return self.execute({'id': element_id})['value']
+
+                def add_command(self):
+                    return ('GET', 'session/$sessionId/path/to/your/custom/$id/url')
+
+            driver = webdriver.Remote('http://localhost:4723/wd/hub', desired_caps,
+                extensions=[CustomYourCommand])
+            element = driver.find_element_by_accessibility_id('id')
+
+            # Then, the driver calls a get request to `session/$sessionId/path/to/your/custom/$id/url`
+            # with replacing the `$id` with the given `element.id`
+            driver.custom_method_name(element.id)
     """
 
-    def __init__(self, execute: Callable):
+    def __init__(self, execute: Callable[[str, Dict], Dict[str, Any]]):
         self._execute = execute
 
     def execute(self, parameters: Any = {}) -> Any:

From 08eb385ecfce967a673bf0a014121e3ce23859b3 Mon Sep 17 00:00:00 2001
From: Kazuaki Matsuo <fly.49.89.over@gmail.com>
Date: Sun, 11 Jul 2021 15:14:57 -0700
Subject: [PATCH 09/12] add types-python-dateutil as error message

---
 Pipfile | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Pipfile b/Pipfile
index b24c835b8..278a6fe95 100644
--- a/Pipfile
+++ b/Pipfile
@@ -18,6 +18,7 @@ tox = "~=3.23"
 
 httpretty = "~=1.0"
 python-dateutil = "~=2.8"
+types-python-dateutil = "~=0.1"
 mock = "~=4.0"
 
 pylint = "~=2.8"

From 5208468360321b8461b23eb7c23211fd044dbff8 Mon Sep 17 00:00:00 2001
From: Kazuaki Matsuo <fly.49.89.over@gmail.com>
Date: Sun, 11 Jul 2021 15:18:22 -0700
Subject: [PATCH 10/12] add example more

---
 appium/webdriver/webdriver.py | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/appium/webdriver/webdriver.py b/appium/webdriver/webdriver.py
index 5ea9a99e8..1f549f160 100644
--- a/appium/webdriver/webdriver.py
+++ b/appium/webdriver/webdriver.py
@@ -150,6 +150,12 @@ def add_command(self):
             # the `value` part of the response.
             driver.custom_method_name()
 
+        4. Remove added commands (if needed)
+            # New commands are added by `setattr`. They remain in the module,
+            # so you should explicitly delete them to define the same name method
+            # with different arguments or process in the method.
+            driver.delete_extensions()
+
 
         You can give arbitrary arguments for the command like the below.
 

From 8bb587f03004da870ccff82b38d048f22895f85f Mon Sep 17 00:00:00 2001
From: Kazuaki Matsuo <fly.49.89.over@gmail.com>
Date: Tue, 13 Jul 2021 22:56:56 -0700
Subject: [PATCH 11/12] tweak naming

---
 appium/webdriver/webdriver.py | 24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/appium/webdriver/webdriver.py b/appium/webdriver/webdriver.py
index 1f549f160..70555d202 100644
--- a/appium/webdriver/webdriver.py
+++ b/appium/webdriver/webdriver.py
@@ -123,7 +123,7 @@ class ExtensionBase:
         `session/$sessionId/path/to/your/custom/url`.
 
         1. Defines an extension as a subclass of `ExtensionBase`
-            class CustomYourCommand(ExtensionBase):
+            class YourCustomCommand(ExtensionBase):
                 def method_name(self):
                     return 'custom_method_name'
 
@@ -141,7 +141,7 @@ def add_command(self):
             # Appium capabilities
             desired_caps = { ... }
             driver = webdriver.Remote('http://localhost:4723/wd/hub', desired_caps,
-                extensions=[CustomYourCommand])
+                extensions=[YourCustomCommand])
 
         3. Calls the custom command
             # Then, the driver calls a get request against
@@ -159,7 +159,7 @@ def add_command(self):
 
         You can give arbitrary arguments for the command like the below.
 
-            class CustomYourCommand(ExtensionBase):
+            class YourCustomCommand(ExtensionBase):
                 def method_name(self):
                     return 'custom_method_name'
 
@@ -170,7 +170,7 @@ def add_command(self):
                     return ('post', 'session/$sessionId/path/to/your/custom/url')
 
             driver = webdriver.Remote('http://localhost:4723/wd/hub', desired_caps,
-                extensions=[CustomYourCommand])
+                extensions=[YourCustomCommand])
 
             # Then, the driver sends a post request to `session/$sessionId/path/to/your/custom/url`
             # with `{'dummy_arg': 'as a value'}` JSON body.
@@ -190,7 +190,7 @@ def add_command(self):
                     return ('GET', 'session/$sessionId/path/to/your/custom/$id/url')
 
             driver = webdriver.Remote('http://localhost:4723/wd/hub', desired_caps,
-                extensions=[CustomYourCommand])
+                extensions=[YourCustomCommand])
             element = driver.find_element_by_accessibility_id('id')
 
             # Then, the driver calls a get request to `session/$sessionId/path/to/your/custom/$id/url`
@@ -287,20 +287,22 @@ def __init__(
         self._extensions = extensions
         for extension in self._extensions:
             instance = extension(self.execute)
-            if hasattr(WebDriver, instance.method_name()):
-                raise ValueError(f'{instance.method_name()} is already defined.')
+            method_name = instance.method_name()
+            if hasattr(WebDriver, method_name):
+                raise ValueError(f'{method_name} is already defined.')
 
             # add a new method named 'instance.method_name()' and call it
-            setattr(WebDriver, instance.method_name(), getattr(instance, instance.method_name()))
+            setattr(WebDriver, method_name, getattr(instance, method_name))
             method, url_cmd = instance.add_command()
-            self.command_executor._commands[instance.method_name()] = (method.upper(), url_cmd)  # type: ignore
+            self.command_executor._commands[method_name] = (method.upper(), url_cmd)  # type: ignore
 
     def delete_extensions(self) -> None:
         """Delete extensions added in the class with 'setattr'"""
         for extension in self._extensions:
             instance = extension(self.execute)
-            if hasattr(WebDriver, instance.method_name()):
-                delattr(WebDriver, instance.method_name())
+            method_name = instance.method_name()
+            if hasattr(WebDriver, method_name):
+                delattr(WebDriver, method_name)
 
     def _update_command_executor(self, keep_alive: bool) -> None:
         """Update command executor following directConnect feature"""

From b5615ff92632659f3e31a59b106f3b2896d2ec49 Mon Sep 17 00:00:00 2001
From: Kazuaki Matsuo <fly.49.89.over@gmail.com>
Date: Tue, 13 Jul 2021 23:07:42 -0700
Subject: [PATCH 12/12] Explicit Dict

---
 appium/webdriver/webdriver.py | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/appium/webdriver/webdriver.py b/appium/webdriver/webdriver.py
index 70555d202..733054364 100644
--- a/appium/webdriver/webdriver.py
+++ b/appium/webdriver/webdriver.py
@@ -201,8 +201,11 @@ def add_command(self):
     def __init__(self, execute: Callable[[str, Dict], Dict[str, Any]]):
         self._execute = execute
 
-    def execute(self, parameters: Any = {}) -> Any:
-        return self._execute(self.method_name(), parameters)
+    def execute(self, parameters: Dict[str, Any] = None) -> Any:
+        param = {}
+        if parameters:
+            param = parameters
+        return self._execute(self.method_name(), param)
 
     def method_name(self) -> str:
         """