Add python sample code (#11208)

* add initial python sample

* add all of ios and android tests

* apply formatter

* add >=0.28 to avoid version error

* tweak versions of default OS

* convert some tests to unittest based ones

* use single quote mainly

* use {} format style for string

* use format syntax

* apply format and tweak assertions

* use is None

* use assert raise

* speficy a number of elements

* tweak exception

* move app path to helper

* tweak assertion conditions

* remove .close since with open() close file automatically

sample-code/python/test/helpers.py

@@ -0,0 +1,44 @@
+import os
+from selenium.common.exceptions import InvalidSessionIdException
+
+
+ANDROID_APP_PATH = 'http://appium.github.io/appium/assets/ApiDemos-debug.apk' if os.getenv(
+    'SAUCE_LABS') else os.path.abspath('../apps/ApiDemos-debug.apk')
+
+IOS_APP_PATH = 'http://appium.github.io/appium/assets/TestApp7.1.app.zip' if os.getenv(
+    'SAUCE_LABS') else os.path.abspath('../apps/TestApp.app.zip')
+
+if os.getenv('SAUCE_USERNAME') and os.getenv('SAUCE_ACCESS_KEY'):
+    EXECUTOR = 'http://{}:{}@ondemand.saucelabs.com:80/wd/hub'.format(
+        os.getenv('SAUCE_USERNAME'), os.getenv('SAUCE_ACCESS_KEY'))
+else:
+    EXECUTOR = 'http://127.0.0.1:4723/wd/hub'
+
+
+def ensure_dir(directory):
+    if not os.path.exists(directory):
+        os.makedirs(directory)
+
+
+def take_screenhot_and_logcat(driver, device_logger, calling_request):
+    __save_log_type(driver, device_logger, calling_request, 'logcat')
+
+
+def take_screenhot_and_syslog(driver, device_logger, calling_request):
+    __save_log_type(driver, device_logger, calling_request, 'syslog')
+
+
+def __save_log_type(driver, device_logger, calling_request, type):
+    logcat_dir = device_logger.logcat_dir
+    screenshot_dir = device_logger.screenshot_dir
+
+    try:
+        driver.save_screenshot(os.path.join(screenshot_dir, calling_request + '.png'))
+        logcat_data = driver.get_log(type)
+    except InvalidSessionIdException:
+        logcat_data = ''
+
+    with open(os.path.join(logcat_dir, '{}_{}.log'.format(calling_request, type)), 'wb') as logcat_file:
+        for data in logcat_data:
+            data_string = '{}:  {}'.format(data['timestamp'], data['message'])
+            logcat_file.write((data_string + '\n').encode('UTF-8'))