Fix metadata filter to not blow up on unmatched nested hashes.

lib/rspec/core/metadata_filter.rb

@@ -67,7 +67,9 @@ def example_group_declaration_line(locations, metadata)
       end
 
       def filters_apply?(key, value, metadata)
-        value.all? { |k, v| filter_applies?(k, v, metadata[key]) }
+        subhash = metadata[key]
+        return false unless Hash === subhash
+        value.all? { |k, v| filter_applies?(k, v, subhash) }
       end
     end
   end

spec/rspec/core/metadata_filter_spec.rb

@@ -138,6 +138,27 @@ def filter_applies?(key, value, metadata)
           }.to raise_error(ArgumentError)
         end
 
+        context "with a nested hash" do
+          it 'matches when the nested entry matches' do
+            metadata = { :foo => { :bar => "words" } }
+            expect(filter_applies?(:foo, { :bar => /wor/ }, metadata)).to be_truthy
+          end
+
+          it 'does not match when the nested entry does not match' do
+            metadata = { :foo => { :bar => "words" } }
+            expect(filter_applies?(:foo, { :bar => /sword/ }, metadata)).to be_falsey
+          end
+
+          it 'does not match when the metadata lacks the key' do
+            expect(filter_applies?(:foo, { :bar => /sword/ }, {})).to be_falsey
+          end
+
+          it 'does not match when the metadata does not have a hash entry for the key' do
+            metadata = { :foo => "words" }
+            expect(filter_applies?(:foo, { :bar => /word/ }, metadata)).to be_falsey
+          end
+        end
+
         context "with an Array" do
           let(:metadata_with_array) do
             meta = nil