Allow rack/mount cascading to be skipped on header

CHANGELOG.markdown

@@ -1,6 +1,7 @@
 Next Release
 ============
 
+* [#340](https://github.com/intridea/grape/pull/339): Allow rack/mount cascading to be skipped on header - [@dieb](https://github.com/dieb).
 * [#333](https://github.com/intridea/grape/pull/333): Validation for array in params - [@flyerhzm](https://github.com/flyerhzm).
 * [#306](https://github.com/intridea/grape/issues/306): Added I18n support for all Grape exceptions - [@niedhui](https://github.com/niedhui).
 * [#294](https://github.com/intridea/grape/issues/294): Extracted `Grape::Entity` into a [grape-entity](https://github.com/agileanimal/grape-entity) gem - [@agileanimal](https://github.com/agileanimal).

README.markdown

@@ -192,7 +192,11 @@ Using this versioning strategy, clients should pass the desired version in the H
 By default, the first matching version is used when no `Accept` header is
 supplied. This behavior is similar to routing in Rails. To circumvent this default behavior,
 one could use the `:strict` option. When this option is set to `true`, a `406 Not Acceptable` error
-is returned when no correct `Accept` header is supplied.
+is returned when no correct `Accept` header is supplied. By default this error contains a
+`X-Cascade` header set to `pass`, allowing nesting and stacking of routes (See
+[Rack::Mount](https://github.com/josh/rack-mount) for more information). To circumvent this default
+behavior, one can set the `:cascade` option to `false`, indicating the `X-Cascade` header may not
+be passed.
 
 ### Path
 
@@ -500,7 +504,7 @@ redirect "/statuses", :permanent => true
 ## Allowed Methods
 
 When you add a `GET` route for a resource, a route for the `HEAD`
-method will also be added automatically. You can disable this 
+method will also be added automatically. You can disable this
 behavior with `do_not_route_head!`.
 
 ``` ruby
@@ -907,7 +911,7 @@ formatter.
 
 ## Authentication
 
-### Basic and Digest Auth 
+### Basic and Digest Auth
 
 Grape has built-in Basic and Digest authentication.
 

lib/grape/middleware/versioner/header.rb

@@ -29,15 +29,15 @@ def before
           if strict?
             # If no Accept header:
             if header.qvalues.empty?
-              throw :error, :status => 406, :headers => {'X-Cascade' => 'pass'}, :message => 'Accept header must be set.'
+              throw :error, :status => 406, :headers => error_headers, :message => 'Accept header must be set.'
             end
             # Remove any acceptable content types with ranges.
             header.qvalues.reject! do |media_type,_|
               Rack::Accept::Header.parse_media_type(media_type).find{|s| s == '*'}
             end
             # If all Accept headers included a range:
             if header.qvalues.empty?
-              throw :error, :status => 406, :headers => {'X-Cascade' => 'pass'}, :message => 'Accept header must not contain ranges ("*").'
+              throw :error, :status => 406, :headers => error_headers, :message => 'Accept header must not contain ranges ("*").'
             end
           end
 
@@ -55,10 +55,10 @@ def before
             end
           # If none of the available content types are acceptable:
           elsif strict?
-            throw :error, :status => 406, :headers => {'X-Cascade' => 'pass'}, :message => '406 Not Acceptable'
+            throw :error, :status => 406, :headers => error_headers, :message => '406 Not Acceptable'
           # If all acceptable content types specify a vendor or version that doesn't exist:
           elsif header.values.all?{ |media_type| has_vendor?(media_type) || has_version?(media_type)}
-            throw :error, :status => 406, :headers => {'X-Cascade' => 'pass'}, :message => 'API vendor or version not found.'
+            throw :error, :status => 406, :headers => error_headers, :message => 'API vendor or version not found.'
           end
         end
 
@@ -95,6 +95,14 @@ def strict?
           options[:version_options] && options[:version_options][:strict]
         end
 
+        def cascade?
+          options[:version_options] && (options[:version_options][:cascade].nil? ? true : options[:version_options][:cascade])
+        end
+
+        def error_headers
+          cascade? ? {'X-Cascade' => 'pass'} : {}
+        end
+
         # @param [String] media_type a content type
         # @return [Boolean] whether the content type sets a vendor
         def has_vendor?(media_type)

spec/grape/middleware/versioner/header_spec.rb

@@ -218,4 +218,60 @@
       subject.call('HTTP_ACCEPT' => 'application/vnd.vendor-v1+json').first.should == 200
     end
   end
+
+  context 'when :strict and :cascade=>false are set' do
+    before do
+      @options[:versions] = ['v1']
+      @options[:version_options][:strict] = true
+      @options[:version_options][:cascade] = false
+    end
+
+    it 'fails with 406 Not Acceptable if header is not set' do
+      expect {
+        env = subject.call({}).last
+      }.to throw_symbol(
+        :error,
+        :status => 406,
+        :headers => {},
+        :message => 'Accept header must be set.'
+      )
+    end
+
+    it 'fails with 406 Not Acceptable if header is empty' do
+      expect {
+        env = subject.call('HTTP_ACCEPT' => '').last
+      }.to throw_symbol(
+        :error,
+        :status => 406,
+        :headers => {},
+        :message => 'Accept header must be set.'
+      )
+    end
+
+    it 'fails with 406 Not Acceptable if type is a range' do
+      expect {
+        env = subject.call('HTTP_ACCEPT' => '*/*').last
+      }.to throw_symbol(
+        :error,
+        :status => 406,
+        :headers => {},
+        :message => 'Accept header must not contain ranges ("*").'
+      )
+    end
+
+    it 'fails with 406 Not Acceptable if subtype is a range' do
+      expect {
+        env = subject.call('HTTP_ACCEPT' => 'application/*').last
+      }.to throw_symbol(
+        :error,
+        :status => 406,
+        :headers => {},
+        :message => 'Accept header must not contain ranges ("*").'
+      )
+    end
+
+    it 'succeeds if proper header is set' do
+      subject.call('HTTP_ACCEPT' => 'application/vnd.vendor-v1+json').first.should == 200
+    end
+  end
 end