Prioritise dependent reps

lib/nanoc/base/services/item_rep_selector.rb

@@ -14,7 +14,7 @@ def each
 
       prioritised = Set.new
       loop do
-        rep = next(graph, prioritised)
+        rep = find(graph, prioritised)
         break if NONE.equal?(rep)
 
         begin
@@ -31,9 +31,20 @@ def each
       end
     end
 
-    def next(graph, _prioritised)
+    def find(graph, prioritised)
       if graph.roots.empty?
         NONE
+      elsif prioritised.any?
+        until prioritised.empty?
+          rep = prioritised.each { |e| break e }
+          if graph.roots.include?(rep)
+            return rep
+          else
+            prioritised.delete(rep)
+          end
+        end
+
+        find(graph, prioritised)
       else
         graph.roots.each { |e| break e }
       end

spec/nanoc/base/services/item_rep_selector_spec.rb

@@ -165,5 +165,20 @@
         expect(tentatively_yielded).to eq [:a, :b, :a, :c, :a, :d, :a, :e, :a]
       end
     end
+
+    context 'unrelated roots' do
+      let(:dependencies) do
+        {
+          a: [:d],
+          b: [:e],
+          c: [],
+        }
+      end
+
+      it 'picks prioritised roots' do
+        expect(successfully_yielded).to eq [:d, :e, :c, :a, :b]
+        expect(tentatively_yielded).to eq [:a, :d, :b, :e, :c, :a, :b]
+      end
+    end
   end
 end