Remove dependency on rest-client. Add mime-types for file upload

Gemfile

@@ -16,6 +16,8 @@ gem "danger-junit", "~> 1.0"
 # A fake filesystem.
 # Version 1.9+ requires Ruby >=2.7, while fastlane uses a `required_ruby_version` of `>= 2.6`.
 gem "fakefs", "1.8"
+# for file uploads with Faraday
+gem "mime-types", ['>= 1.16', '< 4.0']
 # Fast XML parser and object marshaller.
 gem "ox", "2.13.2"
 # Provides an interactive debugging environment for Ruby.
@@ -31,8 +33,6 @@ gem "rake"
 # A readline implementation in Ruby
 # See: https://github.com/deivid-rodriguez/byebug/issues/289#issuecomment-251383465
 gem "rb-readline"
-# A simple and flexible REST client.
-gem "rest-client", ">= 1.8.0"
 # Behavior-driven testing tool for Ruby.
 gem "rspec", "~> 3.10"
 # Formatter for RSpec to generate JUnit compatible reports.

Gemfile.lock

@@ -185,7 +185,6 @@ GEM
       signet (>= 0.16, < 2.a)
     hashdiff (1.0.1)
     highline (2.0.3)
-    http-accept (1.7.0)
     http-cookie (1.0.5)
       domain_name (~> 0.5)
     httpclient (2.8.3)
@@ -198,9 +197,9 @@ GEM
     kramdown-parser-gfm (1.1.0)
       kramdown (~> 2.0)
     method_source (1.0.0)
-    mime-types (3.3.1)
+    mime-types (3.5.2)
       mime-types-data (~> 3.2015)
-    mime-types-data (3.2021.0225)
+    mime-types-data (3.2024.0206)
     mini_magick (4.12.0)
     mini_mime (1.1.5)
     multi_json (1.15.0)
@@ -210,7 +209,6 @@ GEM
     nanaimo (0.3.0)
     nap (1.1.0)
     naturally (2.2.1)
-    netrc (0.11.0)
     no_proxy_fix (0.1.2)
     octokit (4.25.1)
       faraday (>= 1, < 3)
@@ -250,11 +248,6 @@ GEM
       declarative (< 0.1.0)
       trailblazer-option (>= 0.1.1, < 0.2.0)
       uber (< 0.2.0)
-    rest-client (2.1.0)
-      http-accept (>= 1.7.0, < 2.0)
-      http-cookie (>= 1.0.2, < 2.0)
-      mime-types (>= 1.16, < 4.0)
-      netrc (~> 0.8)
     retriable (3.1.2)
     rexml (3.2.6)
     rouge (2.0.7)
@@ -377,14 +370,14 @@ DEPENDENCIES
   fastlane-plugin-clubmate
   fastlane-plugin-ruby
   fastlane-plugin-slack_train (>= 0.2.0)
+  mime-types (>= 1.16, < 4.0)
   ox (= 2.13.2)
   pry
   pry-byebug
   pry-rescue
   pry-stack_explorer
   rake
   rb-readline
-  rest-client (>= 1.8.0)
   rspec (~> 3.10)
   rspec_junit_formatter (~> 0.4.1)
   rubocop (= 1.50.2)

fastlane/lib/fastlane/actions/mailgun.rb

@@ -8,8 +8,15 @@ def self.is_supported?(platform)
       end
 
       def self.run(options)
-        Actions.verify_gem!('rest-client')
-        require 'rest-client'
+        Actions.verify_gem!('faraday')
+        Actions.verify_gem!('mime-types')
+        require 'faraday'
+        begin
+          # Use mime/types/columnar if available, for reduced memory usage
+          require 'mime/types/columnar'
+        rescue LoadError
+          require 'mime/types'
+        end
         handle_params_transition(options)
         mailgunit(options)
       end
@@ -126,14 +133,25 @@ def self.mailgunit(options)
 
         unless options[:attachment].nil?
           attachment_filenames = [*options[:attachment]]
-          attachments = attachment_filenames.map { |filename| File.new(filename, 'rb') }
+          attachments = attachment_filenames.map { |filename| Faraday::UploadIO.new(filename, mime_for(filename), filename) }
           params.store(:attachment, attachments)
         end
 
-        RestClient.post("https://api:#{options[:apikey]}@api.mailgun.net/v3/#{sandbox_domain}/messages", params)
+        conn = Faraday.new(url: "https://api:#{options[:apikey]}@api.mailgun.net") do |f|
+          f.request(:multipart)
+          f.request(:url_encoded)
+          f.adapter(:net_http)
+        end
+        response = conn.post("/v3/#{sandbox_domain}/messages", params)
+        UI.user_error!("Failed to send message via Mailgun, response: #{response.status}: #{response.body}.") if response.status != 200
         mail_template(options)
       end
 
+      def self.mime_for(path)
+        mime = MIME::Types.type_for(path)
+        mime.empty? ? 'text/plain' : mime[0].content_type
+      end
+
       def self.mail_template(options)
         hash = {
           author: Actions.git_author_email,