diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index a8af654b..a4f7c00a 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -12,6 +12,5 @@
     rev: 'v0.761'
     hooks:
     -   id: mypy
-        files: ^appium/
-        entry: mypy appium/
+        entry: mypy appium/ test/
         pass_filenames: false
diff --git a/appium/webdriver/extensions/action_helpers.py b/appium/webdriver/extensions/action_helpers.py
index 98ddbf67..d03d36ee 100644
--- a/appium/webdriver/extensions/action_helpers.py
+++ b/appium/webdriver/extensions/action_helpers.py
@@ -66,7 +66,7 @@ def drag_and_drop(self, origin_el: WebElement, destination_el: WebElement) -> T:
         action.long_press(origin_el).move_to(destination_el).release().perform()
         return self
 
-    def tap(self, positions: List[Tuple], duration: Optional[int] = None) -> T:
+    def tap(self, positions: List[Tuple[int, int]], duration: Optional[int] = None) -> T:
         """Taps on an particular place with up to five fingers, holding for a
         certain time
 
diff --git a/appium/webdriver/extensions/applications.py b/appium/webdriver/extensions/applications.py
index 9ab8a295..3e1939cf 100644
--- a/appium/webdriver/extensions/applications.py
+++ b/appium/webdriver/extensions/applications.py
@@ -172,13 +172,16 @@ class for more details.
         }
         return self.execute(Command.QUERY_APP_STATE, data)['value']
 
-    def app_strings(self, language: str = None, string_file: str = None) -> str:
+    def app_strings(self, language: str = None, string_file: str = None) -> Dict[str, str]:
         """Returns the application strings from the device for the specified
         language.
 
         Args:
             language (str): strings language code
             string_file (str): the name of the string file to query
+
+        Returns:
+            Dict[str, str]: The key is string id and the value is the content.
         """
         data = {}
         if language is not None:
diff --git a/ci.sh b/ci.sh
index a0b1d8fc..1303ff84 100755
--- a/ci.sh
+++ b/ci.sh
@@ -35,7 +35,7 @@ if [[ $? -ne 0 ]] ; then
 fi
 
 (
-  python -m mypy appium
+  python -m mypy appium test
 )
 if [[ $? -ne 0 ]] ; then
   EXIT_STATUS=1
diff --git a/test/functional/android/activities_tests.py b/test/functional/android/activities_tests.py
index 7b1894ff..d13f2d52 100644
--- a/test/functional/android/activities_tests.py
+++ b/test/functional/android/activities_tests.py
@@ -19,25 +19,25 @@
 
 
 class ActivitiesTests(BaseTestCase):
-    def test_current_activity(self):
+    def test_current_activity(self) -> None:
         activity = self.driver.current_activity
         self.assertEqual('.ApiDemos', activity)
 
-    def test_start_activity_this_app(self):
+    def test_start_activity_this_app(self) -> None:
         self.driver.start_activity(APIDEMO_PKG_NAME, ".ApiDemos")
         self._assert_activity_contains('Demos')
 
         self.driver.start_activity(APIDEMO_PKG_NAME, ".accessibility.AccessibilityNodeProviderActivity")
         self._assert_activity_contains('Node')
 
-    def test_start_activity_other_app(self):
+    def test_start_activity_other_app(self) -> None:
         self.driver.start_activity(APIDEMO_PKG_NAME, ".ApiDemos")
         self._assert_activity_contains('Demos')
 
         self.driver.start_activity("com.android.calculator2", ".Calculator")
         self._assert_activity_contains('Calculator')
 
-    def _assert_activity_contains(self, activity):
+    def _assert_activity_contains(self, activity: str) -> None:
         current = self.driver.current_activity
         self.assertTrue(activity in current)
 
diff --git a/test/functional/android/applications_tests.py b/test/functional/android/applications_tests.py
index 45ea52ca..b8b98ffb 100644
--- a/test/functional/android/applications_tests.py
+++ b/test/functional/android/applications_tests.py
@@ -23,33 +23,33 @@
 
 class ApplicationsTests(BaseTestCase):
 
-    def test_background_app(self):
+    def test_background_app(self) -> None:
         self.driver.background_app(1)
         sleep(3)
         self.driver.launch_app()
 
-    def test_is_app_installed(self):
+    def test_is_app_installed(self) -> None:
         self.assertFalse(self.driver.is_app_installed('sdfsdf'))
         self.assertTrue(self.driver.is_app_installed(APIDEMO_PKG_NAME))
 
-    def test_install_app(self):
+    def test_install_app(self) -> None:
         self.skipTest('This causes the server to crash. no idea why')
         self.assertFalse(self.driver.is_app_installed('io.selendroid.testapp'))
         self.driver.install_app('/Users/isaac/code/python-client/test/apps/selendroid-test-app.apk')
         self.assertTrue(self.driver.is_app_installed('io.selendroid.testapp'))
 
-    def test_remove_app(self):
+    def test_remove_app(self) -> None:
         self.assertTrue(self.driver.is_app_installed(APIDEMO_PKG_NAME))
         self.driver.remove_app(APIDEMO_PKG_NAME)
         self.assertFalse(self.driver.is_app_installed(APIDEMO_PKG_NAME))
 
-    def test_close_and_launch_app(self):
+    def test_close_and_launch_app(self) -> None:
         self.driver.close_app()
         self.driver.launch_app()
         activity = self.driver.current_activity
         self.assertEqual('.ApiDemos', activity)
 
-    def test_app_management(self):
+    def test_app_management(self) -> None:
         app_id = self.driver.current_package
         self.assertEqual(self.driver.query_app_state(app_id),
                          ApplicationState.RUNNING_IN_FOREGROUND)
@@ -60,19 +60,19 @@ def test_app_management(self):
         self.assertEqual(self.driver.query_app_state(app_id),
                          ApplicationState.RUNNING_IN_FOREGROUND)
 
-    def test_app_strings(self):
+    def test_app_strings(self) -> None:
         strings = self.driver.app_strings()
         self.assertEqual(u'You can\'t wipe my data, you are a monkey!', strings[u'monkey_wipe_data'])
 
-    def test_app_strings_with_language(self):
+    def test_app_strings_with_language(self) -> None:
         strings = self.driver.app_strings('en')
         self.assertEqual(u'You can\'t wipe my data, you are a monkey!', strings[u'monkey_wipe_data'])
 
-    def test_app_strings_with_language_and_file(self):
+    def test_app_strings_with_language_and_file(self) -> None:
         strings = self.driver.app_strings('en', 'some_file')
         self.assertEqual(u'You can\'t wipe my data, you are a monkey!', strings[u'monkey_wipe_data'])
 
-    def test_reset(self):
+    def test_reset(self) -> None:
         self.driver.reset()
         self.assertTrue(self.driver.is_app_installed(APIDEMO_PKG_NAME))
 
diff --git a/test/functional/android/chrome_tests.py b/test/functional/android/chrome_tests.py
index 32f74216..971e4ebf 100644
--- a/test/functional/android/chrome_tests.py
+++ b/test/functional/android/chrome_tests.py
@@ -20,15 +20,15 @@
 
 
 class ChromeTests(unittest.TestCase):
-    def setUp(self):
+    def setUp(self) -> None:
         caps = get_desired_capabilities()
         caps['browserName'] = 'Chrome'
         self.driver = webdriver.Remote('http://localhost:4723/wd/hub', caps)
 
-    def tearDown(self):
+    def tearDown(self) -> None:
         self.driver.quit()
 
-    def test_find_single_element(self):
+    def test_find_single_element(self) -> None:
         self.driver.get('http://10.0.2.2:4723/test/guinea-pig')
         self.driver.find_element_by_link_text('i am a link').click()
 
diff --git a/test/functional/android/common_tests.py b/test/functional/android/common_tests.py
index 04fb63e8..4da8f793 100644
--- a/test/functional/android/common_tests.py
+++ b/test/functional/android/common_tests.py
@@ -30,15 +30,15 @@
 
 class CommonTests(BaseTestCase):
 
-    def test_current_package(self):
+    def test_current_package(self) -> None:
         self.assertEqual(APIDEMO_PKG_NAME, self.driver.current_package)
 
-    def test_end_test_coverage(self):
+    def test_end_test_coverage(self) -> None:
         self.skipTest('Not sure how to set this up to run')
         self.driver.end_test_coverage(intent='android.intent.action.MAIN', path='')
         sleep(5)
 
-    def test_open_notifications(self):
+    def test_open_notifications(self) -> None:
         if is_ci():
             # TODO Due to unexpected dialog, "System UI isn't responding"
             self.skipTest('Need to fix flaky test during running on CI.')
diff --git a/test/functional/android/context_switching_tests.py b/test/functional/android/context_switching_tests.py
index ed4dcef9..2b42e55d 100644
--- a/test/functional/android/context_switching_tests.py
+++ b/test/functional/android/context_switching_tests.py
@@ -24,37 +24,37 @@
 
 @pytest.mark.skip(reason="Need to fix broken test")
 class ContextSwitchingTests(unittest.TestCase):
-    def setUp(self):
+    def setUp(self) -> None:
         desired_caps = desired_capabilities.get_desired_capabilities('selendroid-test-app.apk')
         self.driver = webdriver.Remote('http://localhost:4723/wd/hub', desired_caps)
 
-    def test_contexts_list(self):
+    def tearDown(self) -> None:
+        self.driver.quit()
+
+    def test_contexts_list(self) -> None:
         self._enter_webview()
         contexts = self.driver.contexts
         self.assertEqual(2, len(contexts))
 
-    def test_move_to_correct_context(self):
+    def test_move_to_correct_context(self) -> None:
         self._enter_webview()
         self.assertEqual('WEBVIEW_io.selendroid.testapp', self.driver.current_context)
 
-    def test_actually_in_webview(self):
+    def test_actually_in_webview(self) -> None:
         self._enter_webview()
         self.driver.find_element_by_css_selector('input[type=submit]').click()
         el = self.driver.find_element_by_xpath("//h1[contains(., 'This is my way')]")
         self.assertIsNot(None, el)
 
-    def test_move_back_to_native_context(self):
+    def test_move_back_to_native_context(self) -> None:
         self._enter_webview()
         self.driver.switch_to.context(None)
         self.assertEqual('NATIVE_APP', self.driver.current_context)
 
-    def test_set_invalid_context(self):
+    def test_set_invalid_context(self) -> None:
         self.assertRaises(NoSuchContextException, self.driver.switch_to.context, 'invalid name')
 
-    def tearDown(self):
-        self.driver.quit()
-
-    def _enter_webview(self):
+    def _enter_webview(self) -> None:
         btn = self.driver.find_element_by_name('buttonStartWebviewCD')
         btn.click()
         self.driver.switch_to.context('WEBVIEW')
diff --git a/test/functional/android/device_time_tests.py b/test/functional/android/device_time_tests.py
index deefdd36..736bf7c6 100644
--- a/test/functional/android/device_time_tests.py
+++ b/test/functional/android/device_time_tests.py
@@ -21,7 +21,7 @@
 
 
 class DeviceTimeTests(BaseTestCase):
-    def test_device_time(self):
+    def test_device_time(self) -> None:
         date_time = self.driver.device_time
         # convert to date ought to work
         parse(date_time)
diff --git a/test/functional/android/finger_print_tests.py b/test/functional/android/finger_print_tests.py
index e77e72a4..cc0457c2 100644
--- a/test/functional/android/finger_print_tests.py
+++ b/test/functional/android/finger_print_tests.py
@@ -19,7 +19,7 @@
 
 
 class FingerPrintTests(BaseTestCase):
-    def test_finger_print(self):
+    def test_finger_print(self) -> None:
         result = self.driver.finger_print(1)
         self.assertEqual(None, result)
 
diff --git a/test/functional/android/helper/desired_capabilities.py b/test/functional/android/helper/desired_capabilities.py
index eccb091a..7ddcd80a 100644
--- a/test/functional/android/helper/desired_capabilities.py
+++ b/test/functional/android/helper/desired_capabilities.py
@@ -13,17 +13,19 @@
 # limitations under the License.
 
 import os
-
+from typing import Any, Dict, Optional
 
 # Returns abs path relative to this file and not cwd
-def PATH(p):
+
+
+def PATH(p: str) -> str:
     return os.path.abspath(
         os.path.join(os.path.dirname(__file__), '..', p)
     )
 
 
-def get_desired_capabilities(app=None):
-    desired_caps = {
+def get_desired_capabilities(app: Optional[str] = None) -> Dict[str, Any]:
+    desired_caps: Dict[str, Any] = {
         'platformName': 'Android',
         'deviceName': 'Android Emulator',
         'newCommandTimeout': 240,
diff --git a/test/functional/android/helper/test_helper.py b/test/functional/android/helper/test_helper.py
index 5813abc6..c8b4af27 100644
--- a/test/functional/android/helper/test_helper.py
+++ b/test/functional/android/helper/test_helper.py
@@ -16,6 +16,7 @@
 import base64
 import os
 import unittest
+from typing import TYPE_CHECKING
 
 from selenium.webdriver.support import expected_conditions as EC
 from selenium.webdriver.support.ui import WebDriverWait
@@ -25,6 +26,10 @@
 
 from . import desired_capabilities
 
+if TYPE_CHECKING:
+    from appium.webdriver.webelement import WebElement
+    from appium.webdriver.webdriver import WebDriver
+
 # the emulator is sometimes slow and needs time to think
 SLEEPY_TIME = 10
 
@@ -32,7 +37,7 @@
 APIDEMO_PKG_NAME = 'io.appium.android.apis'
 
 
-def wait_for_element(driver, locator, value, timeout=SLEEPY_TIME):
+def wait_for_element(driver: 'WebDriver', locator: str, value: str, timeout: int = SLEEPY_TIME) -> 'WebElement':
     """Wait until the element located
 
     Args:
@@ -55,13 +60,13 @@ def wait_for_element(driver, locator, value, timeout=SLEEPY_TIME):
 
 class BaseTestCase(unittest.TestCase):
 
-    def setUp(self):
+    def setUp(self) -> None:
         desired_caps = desired_capabilities.get_desired_capabilities('ApiDemos-debug.apk.zip')
         self.driver = webdriver.Remote('http://localhost:4723/wd/hub', desired_caps)
         if is_ci():
             self.driver.start_recording_screen()
 
-    def tearDown(self):
+    def tearDown(self) -> None:
         if is_ci():
             payload = self.driver.stop_recording_screen()
             video_path = os.path.join(os.getcwd(), self._testMethodName + '.mp4')
diff --git a/test/functional/android/hw_actions_tests.py b/test/functional/android/hw_actions_tests.py
index 3bb022f4..2a6b14e8 100644
--- a/test/functional/android/hw_actions_tests.py
+++ b/test/functional/android/hw_actions_tests.py
@@ -20,7 +20,7 @@
 
 
 class HwActionsTests(BaseTestCase):
-    def test_lock(self):
+    def test_lock(self) -> None:
         self.driver.lock(-1)
         sleep(10)
         try:
diff --git a/test/functional/android/ime_tests.py b/test/functional/android/ime_tests.py
index 6cac0e73..ade988c6 100644
--- a/test/functional/android/ime_tests.py
+++ b/test/functional/android/ime_tests.py
@@ -23,25 +23,25 @@
 
 
 class IMETests(BaseTestCase):
-    def test_available_ime_engines(self):
+    def test_available_ime_engines(self) -> None:
         engines = self.driver.available_ime_engines
         self.assertIsInstance(engines, list)
         self.assertTrue(ANDROID_LATIN in engines or GOOGLE_LATIN in engines)
 
-    def test_is_ime_active(self):
+    def test_is_ime_active(self) -> None:
         self.assertTrue(self.driver.is_ime_active())
 
-    def test_active_ime_engine(self):
+    def test_active_ime_engine(self) -> None:
         engines = self.driver.available_ime_engines
         self.assertTrue(self.driver.active_ime_engine in engines)
 
-    def test_activate_ime_engine(self):
+    def test_activate_ime_engine(self) -> None:
         engines = self.driver.available_ime_engines
 
         self.driver.activate_ime_engine(engines[-1])
         self.assertEqual(self.driver.active_ime_engine, engines[-1])
 
-    def test_deactivate_ime_engine(self):
+    def test_deactivate_ime_engine(self) -> None:
         engines = self.driver.available_ime_engines
         self.driver.activate_ime_engine(engines[-1])
 
diff --git a/test/functional/android/keyboard_tests.py b/test/functional/android/keyboard_tests.py
index 6c634da3..53a5d48c 100644
--- a/test/functional/android/keyboard_tests.py
+++ b/test/functional/android/keyboard_tests.py
@@ -19,12 +19,12 @@
 
 
 class KeyboardTests(BaseTestCase):
-    def test_press_keycode(self):
-        # not sure how to test this.
+    def test_press_keycode(self) -> None:
+        # TODO not sure how to test this.
         self.driver.press_keycode(176)
 
-    def test_long_press_keycode(self):
-        # not sure how to test this.
+    def test_long_press_keycode(self) -> None:
+        # TODO not sure how to test this.
         self.driver.long_press_keycode(176)
 
 
diff --git a/test/functional/android/location_tests.py b/test/functional/android/location_tests.py
index 1584fd5a..68603385 100644
--- a/test/functional/android/location_tests.py
+++ b/test/functional/android/location_tests.py
@@ -19,8 +19,8 @@
 
 
 class LocationTests(BaseTestCase):
-    def test_toggle_location_services(self):
-        self.driver.toggle_location_services()
+    def test_toggle_location_services(self) -> None:
+        self.driver.toggle_location_services()  # TODO Add assert
 
 
 if __name__ == '__main__':
diff --git a/test/functional/android/log_event_tests.py b/test/functional/android/log_event_tests.py
index a64ff9a0..cc3c2b62 100644
--- a/test/functional/android/log_event_tests.py
+++ b/test/functional/android/log_event_tests.py
@@ -19,7 +19,7 @@
 
 
 class LogEventTests(BaseTestCase):
-    def test_log_event(self):
+    def test_log_event(self) -> None:
         vendor = 'appium'
         event = 'funEvent'
         self.driver.log_event(vendor, event)
diff --git a/test/functional/android/multi_action_tests.py b/test/functional/android/multi_action_tests.py
index 3d0be2b0..9904ccbf 100644
--- a/test/functional/android/multi_action_tests.py
+++ b/test/functional/android/multi_action_tests.py
@@ -23,7 +23,7 @@
 
 
 class MultiActionTests(BaseTestCase):
-    def test_parallel_actions(self):
+    def test_parallel_actions(self) -> None:
         el1 = self.driver.find_element_by_accessibility_id('Content')
         el2 = self.driver.find_element_by_accessibility_id('Animation')
         self.driver.scroll(el1, el2)
@@ -55,7 +55,7 @@ def test_parallel_actions(self):
         ma.add(a1, a2)
         ma.perform()
 
-    def test_actions_with_waits(self):
+    def test_actions_with_waits(self) -> None:
         el1 = self.driver.find_element_by_accessibility_id('Content')
         el2 = self.driver.find_element_by_accessibility_id('Animation')
         self.driver.scroll(el1, el2)
@@ -95,7 +95,7 @@ def test_actions_with_waits(self):
         ma.add(a1, a2)
         ma.perform()
 
-    def test_driver_multi_tap(self):
+    def test_driver_multi_tap(self) -> None:
         el = self.driver.find_element_by_accessibility_id('Graphics')
         action = TouchAction(self.driver)
         action.tap(el).perform()
diff --git a/test/functional/android/network_connection_tests.py b/test/functional/android/network_connection_tests.py
index 5727e1d6..73d3816d 100644
--- a/test/functional/android/network_connection_tests.py
+++ b/test/functional/android/network_connection_tests.py
@@ -22,11 +22,11 @@
 
 
 class NetworkConnectionTests(BaseTestCase):
-    def test_get_network_connection(self):
+    def test_get_network_connection(self) -> None:
         nc = self.driver.network_connection
         self.assertIsInstance(nc, int)
 
-    def test_set_network_connection(self):
+    def test_set_network_connection(self) -> None:
         if is_ci():
             self.skipTest('Need to fix flaky test during running on CI')
         nc = self.driver.set_network_connection(ConnectionType.DATA_ONLY)
diff --git a/test/functional/android/remote_fs_tests.py b/test/functional/android/remote_fs_tests.py
index 1a7a0092..db6f3f1e 100644
--- a/test/functional/android/remote_fs_tests.py
+++ b/test/functional/android/remote_fs_tests.py
@@ -23,7 +23,7 @@
 
 
 class RemoteFsTests(BaseTestCase):
-    def test_push_pull_file(self):
+    def test_push_pull_file(self) -> None:
         dest_path = '/data/local/tmp/test_push_file.txt'
         data = bytes('This is the contents of the file to push to the device.', 'utf-8')
 
@@ -32,7 +32,7 @@ def test_push_pull_file(self):
 
         self.assertEqual(data, data_ret)
 
-    def test_pull_folder(self):
+    def test_pull_folder(self) -> None:
         data = bytes('random string data {}'.format(random.randint(0, 1000)), 'utf-8')
         dest_dir = '/data/local/tmp/'
 
@@ -45,7 +45,7 @@ def test_pull_folder(self):
             for filename in ['1.txt', '2.txt']:
                 self.assertTrue(filename in fzip.namelist())
 
-    def test_push_file_with_src_path(self):
+    def test_push_file_with_src_path(self) -> None:
         test_files = ['test_image.jpg', 'test_file.txt']
         for file_name in test_files:
             src_path = os.path.join(os.path.dirname(os.path.abspath(__file__)), 'file', file_name)
diff --git a/test/functional/android/screen_record_tests.py b/test/functional/android/screen_record_tests.py
index 26f5f764..cad3b72b 100644
--- a/test/functional/android/screen_record_tests.py
+++ b/test/functional/android/screen_record_tests.py
@@ -20,7 +20,7 @@
 
 
 class ScreenRecordTests(BaseTestCase):
-    def test_screen_record(self):
+    def test_screen_record(self) -> None:
         self.driver.start_recording_screen(timeLimit=10, forcedRestart=True)
         sleep(10)
         result = self.driver.stop_recording_screen()
diff --git a/test/functional/android/search_context/find_by_accessibility_id_tests.py b/test/functional/android/search_context/find_by_accessibility_id_tests.py
index 508edc21..b3a64507 100644
--- a/test/functional/android/search_context/find_by_accessibility_id_tests.py
+++ b/test/functional/android/search_context/find_by_accessibility_id_tests.py
@@ -23,18 +23,18 @@
 
 
 class FindByAccessibilityIDTests(BaseTestCase):
-    def test_find_single_element(self):
+    def test_find_single_element(self) -> None:
         wait_for_element(self.driver, MobileBy.ANDROID_UIAUTOMATOR, 'new UiSelector().text("Accessibility")').click()
         wait_for_element(self.driver, MobileBy.ANDROID_UIAUTOMATOR,
                          'new UiSelector().text("Accessibility Node Querying")').click()
         el = wait_for_element(self.driver, MobileBy.ACCESSIBILITY_ID, 'Task Take out Trash')
         self.assertIsNotNone(el)
 
-    def test_find_multiple_elements(self):
+    def test_find_multiple_elements(self) -> None:
         els = self.driver.find_elements_by_accessibility_id('Accessibility')
         self.assertIsInstance(els, list)
 
-    def test_element_find_single_element(self):
+    def test_element_find_single_element(self) -> None:
         if is_ci():
             self.skipTest('Need to fix flaky test during running on CI')
         wait_for_element(self.driver, MobileBy.ANDROID_UIAUTOMATOR, 'new UiSelector().text("Accessibility")').click()
@@ -45,7 +45,7 @@ def test_element_find_single_element(self):
         sub_el = el.find_element_by_accessibility_id('Task Take out Trash')
         self.assertIsNotNone(sub_el)
 
-    def test_element_find_multiple_elements(self):
+    def test_element_find_multiple_elements(self) -> None:
         wait_for_element(self.driver, MobileBy.CLASS_NAME, 'android.widget.ListView')
         el = self.driver.find_element_by_class_name('android.widget.ListView')
 
diff --git a/test/functional/android/search_context/find_by_image_tests.py b/test/functional/android/search_context/find_by_image_tests.py
index 9d628c28..8d3440f5 100644
--- a/test/functional/android/search_context/find_by_image_tests.py
+++ b/test/functional/android/search_context/find_by_image_tests.py
@@ -28,7 +28,7 @@
 @pytest.mark.skip(reason="Need to fix broken test")
 class FindByImageTests(unittest.TestCase):
 
-    def setUp(self):
+    def setUp(self) -> None:
         desired_caps = desired_capabilities.get_desired_capabilities('ApiDemos-debug.apk')
         self.driver = webdriver.Remote('http://localhost:4723/wd/hub', desired_caps)
 
@@ -37,10 +37,10 @@ def setUp(self):
                                      "fixImageTemplateSize": True,
                                      "autoUpdateImageElementPosition": True})
 
-    def tearDown(self):
+    def tearDown(self) -> None:
         self.driver.quit()
 
-    def test_find_based_on_image_template(self):
+    def test_find_based_on_image_template(self) -> None:
         image_path = desired_capabilities.PATH('file/find_by_image_success.png')
         print(image_path)
         with open(image_path, 'rb') as png_file:
@@ -64,7 +64,7 @@ def test_find_based_on_image_template(self):
         el.click()
         self.driver.find_element_by_accessibility_id("Alarm")
 
-    def test_find_multiple_elements_by_image_just_returns_one(self):
+    def test_find_multiple_elements_by_image_just_returns_one(self) -> None:
         WebDriverWait(self.driver, 3).until(
             EC.presence_of_element_located((By.ACCESSIBILITY_ID, "App"))
         )
@@ -73,7 +73,7 @@ def test_find_multiple_elements_by_image_just_returns_one(self):
         els[0].click()
         self.driver.find_element_by_accessibility_id("Alarm")
 
-    def test_find_throws_no_such_element(self):
+    def test_find_throws_no_such_element(self) -> None:
         image_path = desired_capabilities.PATH('file/find_by_image_failure.png')
         with open(image_path, 'rb') as png_file:
             b64_data = base64.b64encode(png_file.read()).decode('UTF-8')
diff --git a/test/functional/android/search_context/find_by_uiautomator_tests.py b/test/functional/android/search_context/find_by_uiautomator_tests.py
index 47430356..1e197e8e 100644
--- a/test/functional/android/search_context/find_by_uiautomator_tests.py
+++ b/test/functional/android/search_context/find_by_uiautomator_tests.py
@@ -21,27 +21,27 @@
 
 @pytest.mark.skip(reason="Need to fix flaky test")
 class FindByUIAutomatorTests(BaseTestCase):
-    def test_find_single_element(self):
+    def test_find_single_element(self) -> None:
         el = self.driver.find_element_by_android_uiautomator('new UiSelector().text("Animation")')
         self.assertIsNotNone(el)
 
-    def test_find_multiple_elements(self):
+    def test_find_multiple_elements(self) -> None:
         els = self.driver.find_elements_by_android_uiautomator('new UiSelector().clickable(true)')
         self.assertIsInstance(els, list)
 
-    def test_element_find_single_element(self):
+    def test_element_find_single_element(self) -> None:
         el = self.driver.find_element_by_class_name('android.widget.ListView')
 
         sub_el = el.find_element_by_android_uiautomator('new UiSelector().description("Animation")')
         self.assertIsNotNone(sub_el)
 
-    def test_element_find_multiple_elements(self):
+    def test_element_find_multiple_elements(self) -> None:
         el = self.driver.find_element_by_class_name('android.widget.ListView')
 
         sub_els = el.find_elements_by_android_uiautomator('new UiSelector().clickable(true)')
         self.assertIsInstance(sub_els, list)
 
-    def test_scroll_into_view(self):
+    def test_scroll_into_view(self) -> None:
         el = self.driver.find_element_by_android_uiautomator(
             'new UiScrollable(new UiSelector().scrollable(true).instance(0)).scrollIntoView(new UiSelector().text("Views").instance(0));')
         el.click()
diff --git a/test/functional/android/settings_tests.py b/test/functional/android/settings_tests.py
index a1ffe10b..98f3d667 100644
--- a/test/functional/android/settings_tests.py
+++ b/test/functional/android/settings_tests.py
@@ -19,11 +19,11 @@
 
 
 class SettingsTests(BaseTestCase):
-    def test_get_settings(self):
+    def test_get_settings(self) -> None:
         settings = self.driver.get_settings()
         self.assertIsNotNone(settings)
 
-    def test_update_settings(self):
+    def test_update_settings(self) -> None:
         self.driver.update_settings({"waitForIdleTimeout": 10001})
         settings = self.driver.get_settings()
         self.assertEqual(settings["waitForIdleTimeout"], 10001)
diff --git a/test/functional/android/touch_action_tests.py b/test/functional/android/touch_action_tests.py
index 7bf7e30f..22c11bba 100644
--- a/test/functional/android/touch_action_tests.py
+++ b/test/functional/android/touch_action_tests.py
@@ -27,14 +27,14 @@
 
 
 class TouchActionTests(BaseTestCase):
-    def test_tap(self):
+    def test_tap(self) -> None:
         el = self.driver.find_element_by_accessibility_id('Animation')
         action = TouchAction(self.driver)
         action.tap(el).perform()
         el = wait_for_element(self.driver, MobileBy.ACCESSIBILITY_ID, 'Bouncing Balls')
         self.assertIsNotNone(el)
 
-    def test_tap_x_y(self):
+    def test_tap_x_y(self) -> None:
         el = self.driver.find_element_by_accessibility_id('Animation')
         action = TouchAction(self.driver)
         action.tap(el, 100, 10).perform()
@@ -42,7 +42,7 @@ def test_tap_x_y(self):
         el = wait_for_element(self.driver, MobileBy.ACCESSIBILITY_ID, 'Bouncing Balls')
         self.assertIsNotNone(el)
 
-    def test_tap_twice(self):
+    def test_tap_twice(self) -> None:
         el = self.driver.find_element_by_accessibility_id('Text')
         action = TouchAction(self.driver)
         action.tap(el).perform()
@@ -56,7 +56,7 @@ def test_tap_twice(self):
         els = self.driver.find_elements_by_class_name('android.widget.TextView')
         self.assertEqual('This is a test\nThis is a test\n', els[1].get_attribute("text"))
 
-    def test_press_and_immediately_release(self):
+    def test_press_and_immediately_release(self) -> None:
         el = self.driver.find_element_by_accessibility_id('Animation')
         action = TouchAction(self.driver)
         action.press(el).release().perform()
@@ -64,7 +64,7 @@ def test_press_and_immediately_release(self):
         el = wait_for_element(self.driver, MobileBy.ACCESSIBILITY_ID, 'Bouncing Balls')
         self.assertIsNotNone(el)
 
-    def test_press_and_immediately_release_x_y(self):
+    def test_press_and_immediately_release_x_y(self) -> None:
         el = self.driver.find_element_by_accessibility_id('Animation')
         action = TouchAction(self.driver)
         action.press(el, 100, 10).release().perform()
@@ -72,7 +72,7 @@ def test_press_and_immediately_release_x_y(self):
         el = wait_for_element(self.driver, MobileBy.ACCESSIBILITY_ID, 'Bouncing Balls')
         self.assertIsNotNone(el)
 
-    def test_press_and_wait(self):
+    def test_press_and_wait(self) -> None:
         el1 = self.driver.find_element_by_accessibility_id('Content')
         el2 = self.driver.find_element_by_accessibility_id('Animation')
 
@@ -97,7 +97,7 @@ def test_press_and_wait(self):
                               'new UiSelector().text("Sample menu")')
         self.assertIsNotNone(el)
 
-    def test_press_and_moveto(self):
+    def test_press_and_moveto(self) -> None:
         el1 = self.driver.find_element_by_accessibility_id('Content')
         el2 = self.driver.find_element_by_accessibility_id('Animation')
 
@@ -107,7 +107,7 @@ def test_press_and_moveto(self):
         el = wait_for_element(self.driver, MobileBy.ACCESSIBILITY_ID, 'Views')
         self.assertIsNotNone(el)
 
-    def test_press_and_moveto_x_y(self):
+    def test_press_and_moveto_x_y(self) -> None:
         el1 = self.driver.find_element_by_accessibility_id('Content')
         el2 = self.driver.find_element_by_accessibility_id('App')
 
@@ -117,7 +117,7 @@ def test_press_and_moveto_x_y(self):
         el = wait_for_element(self.driver, MobileBy.ACCESSIBILITY_ID, 'Views')
         self.assertIsNotNone(el)
 
-    def test_long_press(self):
+    def test_long_press(self) -> None:
         el1 = self.driver.find_element_by_accessibility_id('Content')
         el2 = self.driver.find_element_by_accessibility_id('Animation')
 
@@ -142,7 +142,7 @@ def test_long_press(self):
                               'new UiSelector().text("Sample menu")')
         self.assertIsNotNone(el)
 
-    def test_long_press_x_y(self):
+    def test_long_press_x_y(self) -> None:
         el1 = self.driver.find_element_by_accessibility_id('Content')
         el2 = self.driver.find_element_by_accessibility_id('Animation')
 
@@ -167,7 +167,7 @@ def test_long_press_x_y(self):
                               'new UiSelector().text("Sample menu")')
         self.assertIsNotNone(el)
 
-    def test_drag_and_drop(self):
+    def test_drag_and_drop(self) -> None:
         el1 = self.driver.find_element_by_accessibility_id('Content')
         el2 = self.driver.find_element_by_accessibility_id('Animation')
         self.driver.scroll(el1, el2)
@@ -188,7 +188,7 @@ def test_drag_and_drop(self):
         el = wait_for_element(self.driver, MobileBy.ID, '{}:id/drag_text'.format(APIDEMO_PKG_NAME))
         self.assertTrue('drag_dot_3' in el.text)
 
-    def test_driver_drag_and_drop(self):
+    def test_driver_drag_and_drop(self) -> None:
         el1 = self.driver.find_element_by_accessibility_id('Content')
         el2 = self.driver.find_element_by_accessibility_id('Animation')
         self.driver.scroll(el1, el2)
@@ -208,7 +208,7 @@ def test_driver_drag_and_drop(self):
         el = wait_for_element(self.driver, MobileBy.ID, '{}:id/drag_text'.format(APIDEMO_PKG_NAME))
         self.assertTrue('drag_dot_3' in el.text)
 
-    def test_driver_swipe(self):
+    def test_driver_swipe(self) -> None:
         el = self.driver.find_element_by_accessibility_id('Views')
         action = TouchAction(self.driver)
         action.tap(el).perform()
diff --git a/test/functional/android/webelement_tests.py b/test/functional/android/webelement_tests.py
index b936ffc4..bb28782f 100644
--- a/test/functional/android/webelement_tests.py
+++ b/test/functional/android/webelement_tests.py
@@ -25,13 +25,13 @@
 
 
 class WebelementTests(BaseTestCase):
-    def test_element_location_in_view(self):
+    def test_element_location_in_view(self) -> None:
         el = self.driver.find_element_by_accessibility_id('Content')
         loc = el.location_in_view
         self.assertIsNotNone(loc['x'])
         self.assertIsNotNone(loc['y'])
 
-    def test_set_text(self):
+    def test_set_text(self) -> None:
         self.driver.find_element_by_android_uiautomator(
             'new UiScrollable(new UiSelector().scrollable(true).instance(0)).scrollIntoView(new UiSelector().text("Views").instance(0));').click()
 
@@ -44,7 +44,7 @@ def test_set_text(self):
 
         self.assertEqual('new text', el.text)
 
-    def test_send_keys(self):
+    def test_send_keys(self) -> None:
         for text in ['App', 'Activity', 'Custom Title']:
             wait_for_element(self.driver, MobileBy.XPATH,
                              f"//android.widget.TextView[@text='{text}']").click()
diff --git a/test/functional/ios/applications_tests.py b/test/functional/ios/applications_tests.py
index 067aec18..362ab42e 100644
--- a/test/functional/ios/applications_tests.py
+++ b/test/functional/ios/applications_tests.py
@@ -22,7 +22,7 @@
 
 class WebDriverTests(BaseTestCase):
 
-    def test_app_management(self):
+    def test_app_management(self) -> None:
         # this only works in Xcode9+
         if float(desired_capabilities.get_desired_capabilities(
                 desired_capabilities.BUNDLE_ID)['platformVersion']) < 11:
diff --git a/test/functional/ios/execute_driver_tests.py b/test/functional/ios/execute_driver_tests.py
index 4f2251ec..cf696675 100644
--- a/test/functional/ios/execute_driver_tests.py
+++ b/test/functional/ios/execute_driver_tests.py
@@ -19,7 +19,7 @@
 
 
 class ExecuteDriverTests(BaseTestCase):
-    def test_batch(self):
+    def test_batch(self) -> None:
         script = """
             const status = await driver.status();
             console.warn('warning message');
@@ -30,7 +30,7 @@ def test_batch(self):
         assert(response.result['build'])
         assert(response.logs['warn'] == ['warning message'])
 
-    def test_batch_combination_python_script(self):
+    def test_batch_combination_python_script(self) -> None:
         script = """
             console.warn('warning message');
             const element = await driver.findElement('accessibility id', 'Buttons');
diff --git a/test/functional/ios/helper/desired_capabilities.py b/test/functional/ios/helper/desired_capabilities.py
index 12dc982a..633b8e2c 100644
--- a/test/functional/ios/helper/desired_capabilities.py
+++ b/test/functional/ios/helper/desired_capabilities.py
@@ -12,11 +12,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import os
+from typing import Any, Dict, Optional
 
 # Returns abs path relative to this file and not cwd
 
 
-def PATH(p): return os.path.abspath(
+def PATH(p: str) -> str: return os.path.abspath(
     os.path.join(os.path.dirname(__file__), p)
 )
 
@@ -24,8 +25,8 @@ def PATH(p): return os.path.abspath(
 BUNDLE_ID = 'com.example.apple-samplecode.UICatalog'
 
 
-def get_desired_capabilities(app=None):
-    desired_caps = {
+def get_desired_capabilities(app: Optional[str] = None) -> Dict[str, Any]:
+    desired_caps: Dict[str, Any] = {
         'deviceName': iphone_device_name(),
         'platformName': 'iOS',
         'platformVersion': '13.3',
@@ -42,15 +43,15 @@ def get_desired_capabilities(app=None):
 
 
 class PytestXdistWorker:
-    NUMBER = os.getenv('PYTEST_XDIST_WORKER')
-    COUNT = os.getenv('PYTEST_XDIST_WORKER_COUNT')  # Return 2 if `-n 2` is passed
+    NUMBER: Optional[str] = os.getenv('PYTEST_XDIST_WORKER')
+    COUNT: Optional[str] = os.getenv('PYTEST_XDIST_WORKER_COUNT')  # Return 2 if `-n 2` is passed
 
     @staticmethod
-    def gw(number):
+    def gw(number: int) -> str:
         if PytestXdistWorker.COUNT is None:
             return '0'
 
-        if number >= PytestXdistWorker.COUNT:
+        if number >= int(PytestXdistWorker.COUNT):
             return 'gw0'
 
         return f'gw{number}'
@@ -58,7 +59,7 @@ def gw(number):
 # If you run tests with pytest-xdist, you can run tests in parallel.
 
 
-def wda_port():
+def wda_port() -> int:
     if PytestXdistWorker.NUMBER == PytestXdistWorker.gw(1):
         return 8101
 
@@ -68,7 +69,7 @@ def wda_port():
 # Before running tests, you must have iOS simulators named 'iPhone 6s - 8100' and 'iPhone 6s - 8101'
 
 
-def iphone_device_name(port=None):
+def iphone_device_name() -> str:
     if PytestXdistWorker.NUMBER == PytestXdistWorker.gw(0):
         return 'iPhone 8 - 8100'
     elif PytestXdistWorker.NUMBER == PytestXdistWorker.gw(1):
diff --git a/test/functional/ios/helper/test_helper.py b/test/functional/ios/helper/test_helper.py
index 3329bbd6..1e66e46d 100644
--- a/test/functional/ios/helper/test_helper.py
+++ b/test/functional/ios/helper/test_helper.py
@@ -25,13 +25,13 @@
 
 class BaseTestCase(unittest.TestCase):
 
-    def setUp(self):
+    def setUp(self) -> None:
         desired_caps = desired_capabilities.get_desired_capabilities('UICatalog.app.zip')
         self.driver = webdriver.Remote('http://localhost:4723/wd/hub', desired_caps)
         if is_ci():
             self.driver.start_recording_screen()
 
-    def tearDown(self):
+    def tearDown(self) -> None:
         if is_ci():
             payload = self.driver.stop_recording_screen()
             video_path = os.path.join(os.getcwd(), self._testMethodName + '.mp4')
diff --git a/test/functional/ios/hw_actions_tests.py b/test/functional/ios/hw_actions_tests.py
index f37d268d..9f43392f 100644
--- a/test/functional/ios/hw_actions_tests.py
+++ b/test/functional/ios/hw_actions_tests.py
@@ -18,7 +18,7 @@
 
 
 class HwActionsTests(BaseTestCase):
-    def test_lock(self):
+    def test_lock(self) -> None:
         self.driver.lock(-1)
         try:
             self.assertTrue(self.driver.is_locked())
@@ -26,16 +26,16 @@ def test_lock(self):
             self.driver.unlock()
         self.assertFalse(self.driver.is_locked())
 
-    def test_shake(self):
-        # what can we assert about this?
+    def test_shake(self) -> None:
+        # TODO what can we assert about this?
         self.driver.shake()
 
-    def test_touch_id(self):
+    def test_touch_id(self) -> None:
         # nothing to assert, just verify that it doesn't blow up
         self.driver.touch_id(True)
         self.driver.touch_id(False)
 
-    def test_toggle_touch_id_enrollment(self):
+    def test_toggle_touch_id_enrollment(self) -> None:
         # nothing to assert, just verify that it doesn't blow up
         self.driver.toggle_touch_id_enrollment()
 
diff --git a/test/functional/ios/keyboard_tests.py b/test/functional/ios/keyboard_tests.py
index 7ae62347..08ecfdfa 100644
--- a/test/functional/ios/keyboard_tests.py
+++ b/test/functional/ios/keyboard_tests.py
@@ -19,7 +19,7 @@
 
 
 class KeyboardTests(BaseTestCase):
-    def test_hide_keyboard(self):
+    def test_hide_keyboard(self) -> None:
         self._move_to_textbox()
 
         el = self.driver.find_elements_by_class_name('XCUIElementTypeTextField')[0]
@@ -33,7 +33,7 @@ def test_hide_keyboard(self):
 
         self.assertFalse(el.is_displayed())
 
-    def test_hide_keyboard_presskey_strategy(self):
+    def test_hide_keyboard_presskey_strategy(self) -> None:
         self._move_to_textbox()
 
         el = self.driver.find_elements_by_class_name('XCUIElementTypeTextField')[0]
@@ -47,7 +47,7 @@ def test_hide_keyboard_presskey_strategy(self):
 
         self.assertFalse(el.is_displayed())
 
-    def test_hide_keyboard_no_key_name(self):
+    def test_hide_keyboard_no_key_name(self) -> None:
         self._move_to_textbox()
 
         el = self.driver.find_elements_by_class_name('XCUIElementTypeTextField')[0]
@@ -63,7 +63,7 @@ def test_hide_keyboard_no_key_name(self):
         # currently fails.
         self.assertFalse(el.is_displayed())
 
-    def test_is_keyboard_shown(self):
+    def test_is_keyboard_shown(self) -> None:
         self._move_to_textbox()
 
         el = self.driver.find_elements_by_class_name('XCUIElementTypeTextField')[0]
@@ -71,7 +71,7 @@ def test_is_keyboard_shown(self):
         el.set_value('Testing')
         self.assertTrue(self.driver.is_keyboard_shown())
 
-    def _move_to_textbox(self):
+    def _move_to_textbox(self) -> None:
         el1 = self.driver.find_element_by_accessibility_id('Sliders')
         el2 = self.driver.find_element_by_accessibility_id('Buttons')
         self.driver.scroll(el1, el2)
diff --git a/test/functional/ios/remote_fs_tests.py b/test/functional/ios/remote_fs_tests.py
index 4c24b39f..66cad40e 100644
--- a/test/functional/ios/remote_fs_tests.py
+++ b/test/functional/ios/remote_fs_tests.py
@@ -20,7 +20,7 @@
 
 class RemoteFsTests(BaseTestCase):
 
-    def test_push_file(self):
+    def test_push_file(self) -> None:
         file_name = 'test_image.jpg'
         source_path = os.path.join(os.path.dirname(os.path.abspath(__file__)), 'file', file_name)
         destination_path = file_name
diff --git a/test/functional/ios/safari_tests.py b/test/functional/ios/safari_tests.py
index a0b5255f..08c73dd4 100644
--- a/test/functional/ios/safari_tests.py
+++ b/test/functional/ios/safari_tests.py
@@ -20,7 +20,7 @@
 
 
 class SafariTests(unittest.TestCase):
-    def setUp(self):
+    def setUp(self) -> None:
         desired_caps = get_desired_capabilities()
         desired_caps.update({
             'browserName': 'safari',
@@ -30,15 +30,15 @@ def setUp(self):
 
         self.driver = webdriver.Remote('http://localhost:4723/wd/hub', desired_caps)
 
-    def tearDown(self):
+    def tearDown(self) -> None:
         self.driver.quit()
 
-    def test_context(self):
+    def test_context(self) -> None:
         self.assertEqual('NATIVE_APP', self.driver.contexts[0])
         self.assertTrue(self.driver.contexts[1].startswith('WEBVIEW_'))
         self.assertTrue('WEBVIEW_' in self.driver.current_context)
 
-    def test_get(self):
+    def test_get(self) -> None:
         self.driver.get("http://google.com")
         self.assertEqual('Google', self.driver.title)
 
diff --git a/test/functional/ios/screen_record_tests.py b/test/functional/ios/screen_record_tests.py
index 7ad79af6..33a5e98a 100644
--- a/test/functional/ios/screen_record_tests.py
+++ b/test/functional/ios/screen_record_tests.py
@@ -19,7 +19,7 @@
 
 
 class ScreenRecordTests(BaseTestCase):
-    def test_screen_record(self):
+    def test_screen_record(self) -> None:
         self.driver.start_recording_screen()
         sleep(10)
         result = self.driver.stop_recording_screen()
diff --git a/test/functional/ios/search_context/find_by_element_webelement_tests.py b/test/functional/ios/search_context/find_by_element_webelement_tests.py
index 3da2fc42..2e81fec5 100644
--- a/test/functional/ios/search_context/find_by_element_webelement_tests.py
+++ b/test/functional/ios/search_context/find_by_element_webelement_tests.py
@@ -19,7 +19,7 @@
 
 class FindByElementWebelementTests(BaseTestCase):
 
-    def test_find_element_by_path(self):
+    def test_find_element_by_path(self) -> None:
         el = self.driver.find_element_by_ios_predicate('wdName == "UICatalog"')
         self.assertEqual('UICatalog', el.get_attribute('name'))
 
diff --git a/test/functional/ios/search_context/find_by_ios_class_chain_tests.py b/test/functional/ios/search_context/find_by_ios_class_chain_tests.py
index 12537ad3..3c02fb2b 100644
--- a/test/functional/ios/search_context/find_by_ios_class_chain_tests.py
+++ b/test/functional/ios/search_context/find_by_ios_class_chain_tests.py
@@ -18,12 +18,12 @@
 
 
 class FindByIOClassChainTests(BaseTestCase):
-    def test_find_element_by_path(self):
+    def test_find_element_by_path(self) -> None:
         els = self.driver.find_elements_by_ios_class_chain('XCUIElementTypeWindow/**/XCUIElementTypeStaticText')
         self.assertEqual(35, len(els))
         self.assertEqual('UICatalog', els[0].get_attribute('name'))
 
-    def test_find_multiple_elements_by_path(self):
+    def test_find_multiple_elements_by_path(self) -> None:
         el = self.driver.find_elements_by_ios_class_chain('XCUIElementTypeWindow/*/*/*')
         self.assertEqual(2, len(el))
         self.assertEqual('UICatalog', el[0].get_attribute('name'))
diff --git a/test/functional/ios/search_context/find_by_ios_predicate_tests.py b/test/functional/ios/search_context/find_by_ios_predicate_tests.py
index 6890b6b5..6f5bc6d9 100644
--- a/test/functional/ios/search_context/find_by_ios_predicate_tests.py
+++ b/test/functional/ios/search_context/find_by_ios_predicate_tests.py
@@ -18,23 +18,23 @@
 
 
 class FindByIOSPredicateTests(BaseTestCase):
-    def test_find_element_by_name(self):
+    def test_find_element_by_name(self) -> None:
         # Will throw exception if element is not found
         self.driver.find_element_by_ios_predicate('wdName == "Buttons"')
 
-    def test_find_multiple_element_by_type(self):
+    def test_find_multiple_element_by_type(self) -> None:
         e = self.driver.find_elements_by_ios_predicate('wdType == "XCUIElementTypeStaticText"')
         self.assertNotEqual(len(e), 0)
 
-    def test_find_element_by_label(self):
+    def test_find_element_by_label(self) -> None:
         # Will throw exception if element is not found
         self.driver.find_element_by_ios_predicate('label == "Buttons"')
 
-    def test_find_element_by_value(self):
+    def test_find_element_by_value(self) -> None:
         # Will throw exception if element is not found
         self.driver.find_element_by_ios_predicate('wdValue == "Buttons"')
 
-    def test_find_element_by_isvisible(self):
+    def test_find_element_by_isvisible(self) -> None:
         # Will throw exception if element is not found
         self.driver.find_element_by_ios_predicate('wdValue == "Buttons" AND visible == 1')
 
@@ -42,7 +42,7 @@ def test_find_element_by_isvisible(self):
         e = self.driver.find_elements_by_ios_predicate('wdValue == "Buttons" AND visible == 0')
         self.assertEqual(len(e), 0)
 
-    def test_find_element_by_isenabled(self):
+    def test_find_element_by_isenabled(self) -> None:
         # Will throw exception if element is not found
         self.driver.find_element_by_ios_predicate('wdValue == "Buttons" AND enabled == 1')
 
diff --git a/test/functional/ios/webdriver_tests.py b/test/functional/ios/webdriver_tests.py
index 3d0f113f..7a7c5149 100644
--- a/test/functional/ios/webdriver_tests.py
+++ b/test/functional/ios/webdriver_tests.py
@@ -13,6 +13,7 @@
 # limitations under the License.
 
 import unittest
+from typing import TYPE_CHECKING
 
 from selenium.webdriver.support.ui import WebDriverWait
 
@@ -24,10 +25,13 @@
 from ..test_helper import is_ci
 from .helper import desired_capabilities
 
+if TYPE_CHECKING:
+    from appium.webdriver.webdriver import WebDriver
+
 
 class WebDriverTests(BaseTestCase):
 
-    def test_all_sessions(self):
+    def test_all_sessions(self) -> None:
         if is_ci():
             # TODO Due to not created 2nd session somehow
             self.skipTest('Need to fix flaky test during running on CI.')
@@ -39,7 +43,7 @@ def test_all_sessions(self):
         class session_counts_is_two:
             TIMEOUT = 10
 
-            def __call__(self, driver):
+            def __call__(self, driver: 'WebDriver') -> bool:
                 return len(driver.all_sessions) == 2
 
         driver2 = None
@@ -52,7 +56,7 @@ def __call__(self, driver):
             if driver2 is not None:
                 driver2.quit()
 
-    def test_app_management(self):
+    def test_app_management(self) -> None:
         # this only works in Xcode9+
         if float(desired_capabilities.get_desired_capabilities(
                 desired_capabilities.BUNDLE_ID)['platformVersion']) < 11:
@@ -66,7 +70,7 @@ def test_app_management(self):
         self.assertEqual(self.driver.query_app_state(desired_capabilities.BUNDLE_ID),
                          ApplicationState.RUNNING_IN_FOREGROUND)
 
-    def test_clear(self):
+    def test_clear(self) -> None:
         self._move_to_textbox()
 
         el = self.driver.find_elements_by_class_name('XCUIElementTypeTextField')[0]
@@ -90,7 +94,7 @@ def test_clear(self):
         text = el.get_attribute('value')
         self.assertEqual(text, def_text)
 
-    def test_press_button(self):
+    def test_press_button(self) -> None:
         self.driver.press_button("Home")
         if float(desired_capabilities.get_desired_capabilities(
                 desired_capabilities.BUNDLE_ID)['platformVersion']) < 11:
@@ -98,7 +102,7 @@ def test_press_button(self):
         self.assertEqual(self.driver.query_app_state(desired_capabilities.BUNDLE_ID),
                          ApplicationState.RUNNING_IN_FOREGROUND)
 
-    def _move_to_textbox(self):
+    def _move_to_textbox(self) -> None:
         el1 = self.driver.find_element_by_accessibility_id('Sliders')
         el2 = self.driver.find_element_by_accessibility_id('Buttons')
         self.driver.scroll(el1, el2)
diff --git a/test/functional/test_helper.py b/test/functional/test_helper.py
index ee6b6daf..ae55b386 100644
--- a/test/functional/test_helper.py
+++ b/test/functional/test_helper.py
@@ -6,14 +6,21 @@ class NoAvailablePortError(Exception):
     pass
 
 
-def get_available_from_port_range(from_port, to_port):
+def get_available_from_port_range(from_port: int, to_port: int) -> int:
     """Returns available local port number.
+
+    Args:
+        from_port (int): The start port to search
+        to_port (int): The end port to search
+
+    Returns:
+        int: available local port number which are found first
+
     """
-    r = range(from_port, to_port)
 
     sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
 
-    for port in r:
+    for port in range(from_port, to_port):
         try:
             if sock.connect_ex(('localhost', port)) != 0:
                 return port
@@ -23,7 +30,7 @@ def get_available_from_port_range(from_port, to_port):
     raise NoAvailablePortError(f'No available port between {from_port} and {to_port}')
 
 
-def is_ci():
+def is_ci() -> bool:
     """Returns if current execution is running on CI
 
     Returns:
diff --git a/test/unit/helper/test_helper.py b/test/unit/helper/test_helper.py
index 4c1b2d07..b33d3a92 100644
--- a/test/unit/helper/test_helper.py
+++ b/test/unit/helper/test_helper.py
@@ -13,6 +13,7 @@
 # limitations under the License.
 
 import json
+from typing import TYPE_CHECKING, Any, Dict
 
 import httpretty
 
@@ -21,8 +22,12 @@
 # :return: A string of test URL
 SERVER_URL_BASE = 'http://localhost:4723/wd/hub'
 
+if TYPE_CHECKING:
+    from appium.webdriver.webdriver import WebDriver
+    from httpretty.core import HTTPrettyRequestEmpty
 
-def appium_command(command):
+
+def appium_command(command: str) -> str:
     """Return a command of Appium
 
     Returns:
@@ -31,7 +36,7 @@ def appium_command(command):
     return f'{SERVER_URL_BASE}{command}'
 
 
-def android_w3c_driver():
+def android_w3c_driver() -> 'WebDriver':
     """Return a W3C driver which is generated by a mock response for Android
 
     Returns:
@@ -86,7 +91,7 @@ def android_w3c_driver():
     return driver
 
 
-def ios_w3c_driver():
+def ios_w3c_driver() -> 'WebDriver':
     """Return a W3C driver which is generated by a mock response for iOS
 
     Returns:
@@ -127,6 +132,6 @@ def ios_w3c_driver():
     return driver
 
 
-def get_httpretty_request_body(request):
+def get_httpretty_request_body(request: 'HTTPrettyRequestEmpty') -> Dict[str, Any]:
     """Returns utf-8 decoded request body"""
     return json.loads(request.body.decode('utf-8'))