fix python3 set_clipboard error (#267)

* fix python3 set_clipboard error

* apply formatter

Author: KazuCocoa

README.md

@@ -102,7 +102,8 @@ from appium import webdriver
 
 desired_caps = {}
 desired_caps['platformName'] = 'Android'
-desired_caps['platformVersion'] = '4.2'
+desired_caps['platformVersion'] = '8.1'
+desired_caps['automationName'] = 'uiautomator2'
 desired_caps['deviceName'] = 'Android Emulator'
 desired_caps['app'] = PATH('../../../apps/selendroid-test-app.apk')
 
@@ -116,7 +117,8 @@ from appium import webdriver
 
 desired_caps = {}
 desired_caps['platformName'] = 'iOS'
-desired_caps['platformVersion'] = '7.1'
+desired_caps['platformVersion'] = '11.4'
+desired_caps['automationName'] = 'xcuitest'
 desired_caps['deviceName'] = 'iPhone Simulator'
 desired_caps['app'] = PATH('../../apps/UICatalog.app.zip')
 

appium/webdriver/webdriver.py

@@ -1271,7 +1271,7 @@ def set_clipboard(self, content, content_type=ClipboardContentType.PLAINTEXT, la
         :param label: Optional label argument, which only works for Android
         """
         options = {
-            'content': base64.b64encode(content),
+            'content': base64.b64encode(content).decode('UTF-8'),
             'contentType': content_type,
         }
         if label:
@@ -1285,7 +1285,14 @@ def set_clipboard_text(self, text, label=None):
         :param text: The text to be set
         :param label: Optional label argument, which only works for Android
         """
-        self.set_clipboard(bytes(text.encode('UTF-8')), ClipboardContentType.PLAINTEXT, label)
+
+        def _bytes(value, encoding):
+            try:
+                return bytes(value, encoding)  # Python 3
+            except TypeError:
+                return value  # Python 2
+
+        self.set_clipboard(_bytes(str(text), 'UTF-8'), ClipboardContentType.PLAINTEXT, label)
 
     def get_clipboard(self, content_type=ClipboardContentType.PLAINTEXT):
         """