Check migrations properly work in tests

Fixed GeneratorHelpers::migration_class_name because a migration file name
and its migration class name must match each other

lib/generators/statesman/generator_helpers.rb

@@ -9,7 +9,7 @@ def model_file_name
     end
 
     def migration_class_name
-      klass.gsub(/::/, "").pluralize
+      klass.demodulize.pluralize
     end
 
     def next_migration_number

spec/generators/statesman/active_record_transition_generator_spec.rb

@@ -31,6 +31,11 @@
     it "includes the metadata default value when other than MySQL", unless: mysql? do
       expect(migration).to contain(/default: "{}"/)
     end
+
+    it "properly migrates the schema" do
+      require file("db/migrate/#{time}_create_bacon_transitions.rb")
+      expect { CreateBaconTransitions.new.up }.not_to raise_error
+    end
   end
 
   describe "properly adds class names" do

spec/generators/statesman/migration_generator_spec.rb

@@ -48,5 +48,10 @@
       expect(migration).
         to contain("name: \"index_bacon_transitions_parent_most_recent\"")
     end
+
+    it "properly migrates the schema" do
+      require file("db/migrate/#{migration_number}_add_statesman_to_bacon_transitions.rb")
+      expect { AddStatesmanToBaconTransitions.new.up }.not_to raise_error
+    end
   end
 end