add install certificate (#789)

* add install certificate

* append docstring

* update changelog

Author: KazuCocoa

CHANGELOG.md

@@ -5,6 +5,8 @@ Release tags are https://github.com/appium/ruby_lib/releases .
 
 ## Unreleased
 ### 1. Enhancements
+- add `mobile: installCertificate` shortcut for XCUITest
+- add `mobile: getContexts` shortcut for XCUITest
 
 ### 2. Bug fixes
 

lib/appium_lib/ios/xcuitest/command/certificate.rb

@@ -0,0 +1,26 @@
+require 'base64'
+
+module Appium
+  module Ios
+    module Xcuitest
+      module Certificate
+        # Generates Apple's over-the-air configuration profile for certificate deployment
+        # based on the given PEM certificate content.
+        # https://developer.apple.com/library/content/documentation/NetworkingInternet/Conceptual/iPhoneOTAConfiguration/Introduction/Introduction.html
+        # https://github.com/appium/appium-xcuitest-driver/pull/652
+        #
+        # @param [string] cer_file The content of the certificate file.
+        #
+        # @example
+        #
+        #     install_certificate cer_file: "path/to/cert.cer"
+        #
+        def install_certificate(cer_file:)
+          args = { content: Base64.encode64(cer_file) }
+
+          @driver.execute_script 'mobile: installCertificate', args
+        end
+      end
+    end # module Xcuitest
+  end # module Ios
+end # module Appium