Fix searching issues with classifier-reborn (#77)

* Raise Runtime error if no documents are similiar to the document you are searching for

* Reject documents that are composed of stopwords and words that are 2 characters or less

* Remove remenants of debugging code

lib/classifier-reborn/lsi.rb

@@ -64,6 +64,9 @@ def needs_rebuild?
     #
     def add_item(item, *categories, &block)
       clean_word_hash = Hasher.clean_word_hash((block ? block.call(item) : item.to_s), @language)
+      if clean_word_hash.empty?
+        raise "#{item} is composed entirely of stopwords and words that are 2 characters or less. Classifier-Reborn cannot handle this document properly, and thus summarily rejected it."
+      end
       @items[item] = if @cache_node_vectors
                        CachedContentNode.new(clean_word_hash, *categories)
                      else
@@ -200,6 +203,11 @@ def proximity_norms_for_content(doc, &block)
       return [] if needs_rebuild?
 
       content_node = node_for_content(doc, &block)
+
+      if $GSL && content_node.raw_norm.isnan?.all?
+        raise "There are no documents that are similar to #{doc}"
+      end
+
       result =
         @items.keys.collect do |item|
           if $GSL

test/lsi/lsi_test.rb

@@ -181,6 +181,26 @@ def test_keyword_search
     assert_equal [:dog, :text, :deal], lsi.highest_ranked_stems(@str1)
   end
 
+  def test_invalid_searching_when_using_gsl
+    return unless $GSL
+    lsi = ClassifierReborn::LSI.new
+    lsi.add_item @str1, 'Dog'
+    lsi.add_item @str2, 'Dog'
+    lsi.add_item @str3, 'Cat'
+    lsi.add_item @str4, 'Cat'
+    lsi.add_item @str5, 'Bird'
+    assert_raises RuntimeError do
+      lsi.search('penguin')
+    end
+  end
+
+  def test_raise_error_when_adding_bad_document
+    lsi = ClassifierReborn::LSI.new
+    assert_raises RuntimeError do
+      lsi.add_item("i can")
+    end
+  end
+
   def test_summary
     assert_equal 'This text involves dogs too [...] This text also involves cats', Summarizer.summary([@str1, @str2, @str3, @str4, @str5].join, 2)
   end