Set X-Cascade header when using pass

Setting X-Cascade: pass allows middleware outside the Sinatra stack
to continue trying to match the request.

Signed-off-by: Ryan Tomayko <rtomayko@gmail.com>

lib/sinatra/base.rb

@@ -583,9 +583,10 @@ module Sinatra
     end
 
     def handle_not_found!(boom)
-      @env['sinatra.error'] = boom
-      @response.status      = 404
-      @response.body        = ['<h1>Not Found</h1>']
+      @env['sinatra.error']          = boom
+      @response.status               = 404
+      @response.headers['X-Cascade'] = 'pass'
+      @response.body                 = ['<h1>Not Found</h1>']
       error_block! boom.class, NotFound
     end
 

test/helpers_test.rb

@@ -142,6 +142,19 @@ class HelpersTest < Test::Unit::TestCase
       assert_equal 404, status
       assert_equal '', body
     end
+
+    it 'does not set a X-Cascade header' do
+      mock_app {
+        get '/' do
+          not_found
+          fail 'not_found should halt'
+        end
+      }
+
+      get '/'
+      assert_equal 404, status
+      assert_equal nil, response.headers['X-Cascade']
+    end
   end
 
   describe 'headers' do

test/routing_test.rb

@@ -60,6 +60,15 @@ class RoutingTest < Test::Unit::TestCase
     assert_equal 404, status
   end
 
+  it "404s and sets X-Cascade header when no route satisfies the request" do
+    mock_app {
+      get('/foo') { }
+    }
+    get '/bar'
+    assert_equal 404, status
+    assert_equal 'pass', response.headers['X-Cascade']
+  end
+
   it "overrides the content-type in error handlers" do
     mock_app {
       before { content_type 'text/plain' }
@@ -462,6 +471,23 @@ class RoutingTest < Test::Unit::TestCase
     assert not_found?
   end
 
+  it "transitions to 404 and sets X-Cascade header when passed and no subsequent route matches" do
+    mock_app {
+      get '/:foo' do
+        pass
+        'Hello Foo'
+      end
+
+      get '/bar' do
+        'Hello Bar'
+      end
+    }
+
+    get '/foo'
+    assert not_found?
+    assert_equal 'pass', response.headers['X-Cascade']
+  end
+
   it "uses optional block passed to pass as route block if no other route is found" do
     mock_app {
       get "/" do