Fix validation order - validate file format before encoding

Author: Skumring

lib/active_admin_import/model.rb

@@ -37,7 +37,7 @@ module CONST
     validate :file_contents_present, if: ->(me) { me.file.present? }
 
     before_validation :unzip_file, if: ->(me) { me.archive? && me.allow_archive? }
-    before_validation :encode_file, if: ->(me) { me.force_encoding? && me.file.present? }
+    after_validation :encode_file, if: ->(me) { me.force_encoding? && me.file.present? }
 
     attr_reader :attributes
 

spec/fixtures/files/author_invalid_format.txt

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

spec/import_spec.rb

@@ -610,4 +610,20 @@ def upload_file!(name, ext = 'csv')
       end.not_to change { Author.count }
     end
   end
+
+  context 'when importing file with invalid format and auto force_encoding' do
+    let(:options) { { template_object: ActiveAdminImport::Model.new(force_encoding: :auto) } }
+
+    before do
+      add_author_resource(options)
+      visit '/admin/authors/import'
+    end
+
+    it 'should reject invalid file format before encoding' do
+      expect do
+        upload_file!(:author_invalid_format, 'txt')
+        expect(page).to have_content I18n.t('active_admin_import.file_format_error')
+      end.not_to change { Author.count }
+    end
+  end
 end