Treat headers as case-insensitive so duplicate headers are not a problem

lib/mailgun/version.rb

@@ -1,4 +1,4 @@
 # It's the version. Yeay!
 module Mailgun
-  VERSION = '1.1.11'
+  VERSION = '1.2.0'
 end

lib/railgun/mailer.rb

@@ -11,7 +11,7 @@ module Railgun
   class Mailer
 
     # List of the headers that will be ignored when copying headers from `mail.header_fields`
-    IGNORED_HEADERS = %w[ to from subject ]
+    IGNORED_HEADERS = %w[ to from subject reply-to ]
 
     # [Hash] config ->
     #   Requires *at least* `api_key` and `domain` keys.
@@ -27,7 +27,12 @@ def initialize(config)
         raise Railgun::ConfigurationError.new("Config requires `#{k}` key", @config) unless @config.has_key?(k)
       end
 
-      @mg_client = Mailgun::Client.new(config[:api_key], config[:api_host] || 'api.mailgun.net', config[:api_version] || 'v3', config[:api_ssl].nil? ? true : config[:api_ssl])
+      @mg_client = Mailgun::Client.new(
+        config[:api_key],
+        config[:api_host] || 'api.mailgun.net',
+        config[:api_version] || 'v3',
+        config[:api_ssl].nil? ? true : config[:api_ssl],
+      )
       @domain = @config[:domain]
 
       # To avoid exception in mail gem v2.6
@@ -62,6 +67,9 @@ def mailgun_client
   # After prefixing them with the proper option type, they are added to
   # the message hash where they will then be sent to the API as JSON.
   #
+  # It is important to note that headers set in `mailgun_headers` on the message
+  # WILL overwrite headers set via `mail.headers()`.
+  #
   # @param [Mail::Message] mail message to transform
   #
   # @return [Hash] transformed message hash
@@ -85,12 +93,17 @@ def transform_for_mailgun(mail)
     msg_headers = Hash.new
 
     # h:* attributes (headers)
-    mail.mailgun_headers.try(:each) do |k, v|
-      msg_headers[k] = v
-    end
 
+    # Let's set all of these headers on the [Mail::Message] so that
+    # the are created inside of a [Mail::Header] instance and processed there.
+    mail.headers(mail.mailgun_headers || {})
     mail.header_fields.each do |field|
-      msg_headers[field.name] = field.value
+      header = field.name.downcase
+      if msg_headers.include? header
+        msg_headers[header] = [msg_headers[header], field.value].flatten
+      else
+        msg_headers[header] = field.value
+      end
     end
 
     msg_headers.each do |k, v|

mailgun.gemspec

@@ -24,9 +24,9 @@ Gem::Specification.new do |spec|
 
   spec.required_ruby_version = '>= 2.2.2'
 
-  spec.add_development_dependency 'bundler', '~> 1.16.2'
+  spec.add_development_dependency 'bundler', '>= 1.16.2'
   spec.add_development_dependency 'rspec', '~> 3.8.0'
-  spec.add_development_dependency 'rake', '~> 12.3.1'
+  spec.add_development_dependency 'rake', '~> 12.3.2'
   spec.add_development_dependency 'webmock', '~> 3.4.2'
   spec.add_development_dependency 'pry', '~> 0.11.3'
   spec.add_development_dependency 'vcr', '~> 3.0.3'

spec/unit/railgun/mailer_spec.rb

@@ -92,24 +92,24 @@ def message_with_attachment(address, subject)
   it 'adds headers to message body' do
     message = UnitTestMailer.plain_message('test@example.org', '', {})
     message.mailgun_headers ||= {
-      'X-Unit-Test' => 'true',
+      'x-unit-test' => 'true',
     }
 
     body = Railgun.transform_for_mailgun(message)
 
-    expect(body).to include('h:X-Unit-Test')
-    expect(body['h:X-Unit-Test']).to eq('true')
+    expect(body).to include('h:x-unit-test')
+    expect(body['h:x-unit-test']).to eq('true')
   end
 
   it 'adds headers to message body from mailer' do
     message = UnitTestMailer.plain_message('test@example.org', '', {
-      'X-Unit-Test-2' => 'true',
+      'x-unit-test-2' => 'true',
     })
 
     body = Railgun.transform_for_mailgun(message)
 
-    expect(body).to include('h:X-Unit-Test-2')
-    expect(body['h:X-Unit-Test-2']).to eq('true')
+    expect(body).to include('h:x-unit-test-2')
+    expect(body['h:x-unit-test-2']).to eq('true')
   end
 
   it 'properly handles headers that are passed as separate POST params' do
@@ -131,7 +131,7 @@ def message_with_attachment(address, subject)
       expect(body).not_to include("h:#{header}")
     end
 
-    ['bcc', 'cc', 'to', 'h:X-Source'].each do |param|
+    ['bcc', 'cc', 'to', 'h:x-source'].each do |param|
       expect(body).to include(param)
     end
 
@@ -142,7 +142,7 @@ def message_with_attachment(address, subject)
     expect(body[:html]).to eq(['<p>Test!</p>'.html_safe])
     expect(body['bcc']).to eq(['list@example.org'])
     expect(body['cc']).to eq(['admin@example.com'])
-    expect(body['h:X-Source']).to eq('unit tests')
+    expect(body['h:x-source']).to eq('unit tests')
   end
 
   it 'properly adds attachments' do
@@ -163,4 +163,55 @@ def message_with_attachment(address, subject)
     expect(ActionMailer::Base.deliveries).to include(message)
   end
 
+  it 'ignores `reply-to` in headers' do
+    message = UnitTestMailer.plain_message('test@example.org', '', {
+      'reply-to' => 'user@example.com',
+    })
+    message.mailgun_headers = {
+      'Reply-To' => 'administrator@example.org',
+    }
+    message.headers({'REPLY-TO' => 'admin@example.net'})
+    message.reply_to = "dude@example.com.au"
+
+    body = Railgun.transform_for_mailgun(message)
+    expect(body).to include('h:reply-to')
+    expect(body).not_to include('h:Reply-To')
+    expect(body['h:reply-to']).to eq('dude@example.com.au')
+  end
+
+  it 'treats `headers()` names as case-insensitve' do
+    message = UnitTestMailer.plain_message('test@example.org', '', {
+      'X-BIG-VALUE' => 1,
+    })
+
+    body = Railgun.transform_for_mailgun(message)
+    expect(body).to include('h:x-big-value')
+    expect(body['h:x-big-value']).to eq("1")
+  end
+
+  it 'treats `mailgun_headers` names as case-insensitive' do
+    message = UnitTestMailer.plain_message('test@example.org', '', {})
+    message.mailgun_headers = {
+      'X-BIG-VALUE' => 1,
+    }
+
+    body = Railgun.transform_for_mailgun(message)
+    expect(body).to include('h:x-big-value')
+    expect(body['h:x-big-value']).to eq("1")
+  end
+
+  it 'handles multi-value, mixed case headers correctly' do
+    message = UnitTestMailer.plain_message('test@example.org', '', {})
+    message.headers({
+      'x-neat-header' => 'foo',
+      'X-Neat-Header' => 'bar',
+      'X-NEAT-HEADER' => 'zoop',
+    })
+
+    body = Railgun.transform_for_mailgun(message)
+    expect(body).to include('h:x-neat-header')
+    expect(body['h:x-neat-header']).to include('foo')
+    expect(body['h:x-neat-header']).to include('bar')
+    expect(body['h:x-neat-header']).to include('zoop')
+  end
 end