fix handling of rewrite headers option

Author: Fivell

lib/active_admin_import/importer.rb

@@ -80,7 +80,7 @@ def import_options
     protected
 
     def prepare_headers(headers)
-      @headers = Hash[headers.zip(headers.map { |el| el.underscore.gsub(/\s+/, '_') })]
+      @headers = Hash[headers.zip(headers.map { |el| el.underscore.gsub(/\s+/, '_') })].with_indifferent_access
       @headers.merge!(options[:headers_rewrites])
       @headers
     end

lib/active_admin_import/options.rb

@@ -16,7 +16,8 @@ module ActiveAdminImport
         :template_object,
         :resource_class,
         :resource_label,
-        :plural_resource_label
+        :plural_resource_label ,
+        :headers_rewrites
       ].freeze
 
 

spec/fixtures/files/author_broken_header.csv

@@ -0,0 +1,2 @@
+Name,Second name,Birthday
+John,Doe,1986-05-01

spec/import_spec.rb

@@ -145,6 +145,20 @@ def upload_file!(name, ext='csv')
         end
       end
 
+      context "with different header attribute names" do
+
+        let(:options) {
+                  {
+                      headers_rewrites:  { :'Second name' =>  :last_name }
+                  }
+        }
+
+        it "should import file" do
+          upload_file!(:author_broken_header)
+          expect(page).to have_content "Successfully imported 1 author"
+          expect(Author.count).to eq(1)
+        end
+      end
 
       context "with semicolons separator" do
         let(:options) {