Added specs for slugs on dashes and underscore-type situations.

.rubocop_todo.yml

@@ -1,6 +1,6 @@
 # This configuration was generated by
 # `rubocop --auto-gen-config`
-# on 2016-09-07 14:58:20 -0400 using RuboCop version 0.34.2.
+# on 2016-09-07 16:18:43 -0400 using RuboCop version 0.34.2.
 # The point is for the user to remove these configuration records
 # one by one as the offenses are removed from the code base.
 # Note that changes in the inspected code, or installation of new
@@ -27,7 +27,7 @@ Metrics/MethodLength:
 # Offense count: 2
 # Configuration parameters: CountComments.
 Metrics/ModuleLength:
-  Max: 939
+  Max: 947
 
 # Offense count: 3
 Metrics/PerceivedComplexity:

spec/mongoid/slug_spec.rb

@@ -7,8 +7,8 @@ module Mongoid
       Book.create(title: 'A Thousand Plateaus')
     end
 
-    context 'should not persist incorrect slugs' do
-      it 'slugs should not be generated from invalid documents' do
+    context 'special cases' do
+      it 'slugs are not be generated from invalid documents' do
         # this will fail now
         x = IncorrectSlugPersistence.create!(name: 'test')
         expect(x.slug).to eq('test')
@@ -28,6 +28,16 @@ module Mongoid
         expect(book.reload.slugs).to eq ['book']
       end
 
+      it 'defaults slugs for dashes' do
+        book = Book.create!(title: '-')
+        expect(book.reload.slugs).to eq ['book']
+      end
+
+      it 'defaults slugs for underscores' do
+        book = Book.create!(title: '_')
+        expect(book.reload.slugs).to eq ['book']
+      end
+
       it 'defaults slugs for nil strings' do
         book = Book.create!
         expect(book.reload.slugs).to eq ['book']