Default to the Work headers if object type is nil or undefined (#137)

* Default to the Work headers if object type is nil or undefined

* Update test to reflect fixture

app/uploaders/zizia/csv_manifest_validator.rb

@@ -72,13 +72,18 @@ def missing_headers
     end
 
     def required_headers(object_type = "w")
+      return work_headers if object_type.nil?
       if object_type.casecmp("c").zero? || object_type.casecmp("collection").zero?
         ['title', 'visibility']
       else
-        ['title', 'creator', 'keyword', 'rights statement', 'visibility', 'files', 'deduplication_key']
+        work_headers
       end
     end
 
+    def work_headers
+      ['title', 'creator', 'keyword', 'rights statement', 'visibility', 'files', 'deduplication_key']
+    end
+
     def duplicate_headers
       duplicates = []
       sorted_headers = @transformed_headers.sort

spec/dummy/spec/fixtures/csv_import/good/mix_of_object_types.csv

@@ -4,3 +4,4 @@ Collection,Collection of fruits,,,,public,,def/234
 w,Work on tomatoes,"Tomato, Tommy",fruits|~|tomatoes,http://rightsstatements.org/vocab/InC/1.0/,public,birds.jpg,abc/123
 wOrk,Work on cabbages,"Cabbage, Carl",vegetables|~|cabbages,http://rightsstatements.org/vocab/InC/1.0/,public,dog.jpg,abs/234
 coLLEction,Collection of legumes,,,,public,,def/345
+,Work without object type,"Cabbage, Carl",vegetables|~|cabbages,http://rightsstatements.org/vocab/InC/1.0/,public,dog.jpg,abc/345

spec/dummy/spec/system/import_from_csv_spec.rb

@@ -90,7 +90,7 @@
             attach_file('csv_import[manifest]', csv_file, make_visible: true)
             click_on 'Preview Import'
             click_on 'Start Import'
-          end.to change { Work.count }.by(2)
+          end.to change { Work.count }.by(3)
              .and change { Collection.count }.by(3)
         end
       end