also cache nil (doc not found) to avoid multiple requests

lib/couch_potato/database.rb

@@ -149,7 +149,7 @@ def load_document(id)
 
       cached = cache && cache[id]
       if cache
-        if cached
+        if cache.key?(id)
           ActiveSupport::Notifications.instrument('couch_potato.load.cached', id: id, doc: cached) do
             cached
           end
@@ -178,7 +178,7 @@ def load_documents(ids)
       if cache
         uncached_ids.each do |id|
           doc = uncached_docs_by_id[id]
-          cache[id] = doc if doc
+          cache[id] = doc
         end
       end
       ids.filter_map { |id| (cached_docs_by_id[id]) || uncached_docs_by_id[id] }

spec/unit/caching_spec.rb

@@ -37,6 +37,15 @@
       db.load '1'
     end
 
+    it 'caches nil' do
+      allow(couchrest_db).to receive(:get).with('1').and_return(nil)
+
+      db.load '1'
+      db.load '1'
+
+      expect(couchrest_db).to have_received(:get).with('1').exactly(1).times
+    end
+
     it 'gets an object from the cache the 2nd time via #load!' do
       expect(couchrest_db).to receive(:get).with('1').exactly(1).times
 
@@ -92,6 +101,17 @@
       expect(couchrest_db).to have_received(:bulk_load).with(['2']).exactly(1).times
     end
 
+    it 'caches nil' do
+      allow(couchrest_db).to receive(:bulk_load).with(['1']).and_return('rows' => [{'doc' => nil}])
+      allow(couchrest_db).to receive(:bulk_load).with(['2']).and_return('rows' => [{'doc' => doc2}])
+
+
+      db.load_document(['1'])
+      db.load_document(['1', '2'])
+
+      expect(couchrest_db).to have_received(:bulk_load).with(['1']).exactly(1).times
+    end
+
     it 'instruments the load call' do
       allow(couchrest_db).to receive(:bulk_load).with(['1'])
         .and_return('rows' => [{'doc' => doc1}])
@@ -137,22 +157,6 @@
 
       expect(result).to eql([doc1, doc2])
     end
-
-    it 'does not cache documents that do not respond to id' do
-      doc1 = {
-        'id' => '1',
-      }
-      doc2 = {
-        'id' => '2',
-      }
-      allow(couchrest_db).to receive(:bulk_load).with(['1', '2'])
-        .and_return('rows' => [{'doc' => doc1}, {'doc' => doc2}])
-
-      db.load_document(['1', '2'])
-      db.load_document(['1', '2'])
-
-      expect(couchrest_db).to have_received(:bulk_load).with(['1', '2']).exactly(2).times
-    end
   end
 
   context 'when switching the database' do