Pull namespace defaults out of the options hash

If a developer has specified either :path or :as in the options hash then
these should be used as the defaults for :shallow_path and :shallow_prefix.

Fixes #14241.

actionpack/lib/action_dispatch/routing/mapper.rb

@@ -792,9 +792,16 @@ def controller(controller, options={})
         #   end
         def namespace(path, options = {})
           path = path.to_s
-          options = { :path => path, :as => path, :module => path,
-                      :shallow_path => path, :shallow_prefix => path }.merge!(options)
-          scope(options) { yield }
+
+          defaults = {
+            module:         path,
+            path:           options.fetch(:path, path),
+            as:             options.fetch(:as, path),
+            shallow_path:   options.fetch(:path, path),
+            shallow_prefix: options.fetch(:as, path)
+          }
+
+          scope(defaults.merge!(options)) { yield }
         end
 
         # === Parameter Restriction

actionpack/test/dispatch/routing_test.rb

@@ -1031,6 +1031,136 @@ def test_namespace_with_options
     assert_equal 'users/home#index', @response.body
   end
 
+  def test_namespaced_shallow_routes_with_module_option
+    draw do
+      namespace :foo, module: 'bar' do
+        resources :posts, only: [:index, :show] do
+          resources :comments, only: [:index, :show], shallow: true
+        end
+      end
+    end
+
+    get '/foo/posts'
+    assert_equal '/foo/posts', foo_posts_path
+    assert_equal 'bar/posts#index', @response.body
+
+    get '/foo/posts/1'
+    assert_equal '/foo/posts/1', foo_post_path('1')
+    assert_equal 'bar/posts#show', @response.body
+
+    get '/foo/posts/1/comments'
+    assert_equal '/foo/posts/1/comments', foo_post_comments_path('1')
+    assert_equal 'bar/comments#index', @response.body
+
+    get '/foo/comments/2'
+    assert_equal '/foo/comments/2', foo_comment_path('2')
+    assert_equal 'bar/comments#show', @response.body
+  end
+
+  def test_namespaced_shallow_routes_with_path_option
+    draw do
+      namespace :foo, path: 'bar' do
+        resources :posts, only: [:index, :show] do
+          resources :comments, only: [:index, :show], shallow: true
+        end
+      end
+    end
+
+    get '/bar/posts'
+    assert_equal '/bar/posts', foo_posts_path
+    assert_equal 'foo/posts#index', @response.body
+
+    get '/bar/posts/1'
+    assert_equal '/bar/posts/1', foo_post_path('1')
+    assert_equal 'foo/posts#show', @response.body
+
+    get '/bar/posts/1/comments'
+    assert_equal '/bar/posts/1/comments', foo_post_comments_path('1')
+    assert_equal 'foo/comments#index', @response.body
+
+    get '/bar/comments/2'
+    assert_equal '/bar/comments/2', foo_comment_path('2')
+    assert_equal 'foo/comments#show', @response.body
+  end
+
+  def test_namespaced_shallow_routes_with_as_option
+    draw do
+      namespace :foo, as: 'bar' do
+        resources :posts, only: [:index, :show] do
+          resources :comments, only: [:index, :show], shallow: true
+        end
+      end
+    end
+
+    get '/foo/posts'
+    assert_equal '/foo/posts', bar_posts_path
+    assert_equal 'foo/posts#index', @response.body
+
+    get '/foo/posts/1'
+    assert_equal '/foo/posts/1', bar_post_path('1')
+    assert_equal 'foo/posts#show', @response.body
+
+    get '/foo/posts/1/comments'
+    assert_equal '/foo/posts/1/comments', bar_post_comments_path('1')
+    assert_equal 'foo/comments#index', @response.body
+
+    get '/foo/comments/2'
+    assert_equal '/foo/comments/2', bar_comment_path('2')
+    assert_equal 'foo/comments#show', @response.body
+  end
+
+  def test_namespaced_shallow_routes_with_shallow_path_option
+    draw do
+      namespace :foo, shallow_path: 'bar' do
+        resources :posts, only: [:index, :show] do
+          resources :comments, only: [:index, :show], shallow: true
+        end
+      end
+    end
+
+    get '/foo/posts'
+    assert_equal '/foo/posts', foo_posts_path
+    assert_equal 'foo/posts#index', @response.body
+
+    get '/foo/posts/1'
+    assert_equal '/foo/posts/1', foo_post_path('1')
+    assert_equal 'foo/posts#show', @response.body
+
+    get '/foo/posts/1/comments'
+    assert_equal '/foo/posts/1/comments', foo_post_comments_path('1')
+    assert_equal 'foo/comments#index', @response.body
+
+    get '/bar/comments/2'
+    assert_equal '/bar/comments/2', foo_comment_path('2')
+    assert_equal 'foo/comments#show', @response.body
+  end
+
+  def test_namespaced_shallow_routes_with_shallow_prefix_option
+    draw do
+      namespace :foo, shallow_prefix: 'bar' do
+        resources :posts, only: [:index, :show] do
+          resources :comments, only: [:index, :show], shallow: true
+        end
+      end
+    end
+
+    get '/foo/posts'
+    assert_equal '/foo/posts', foo_posts_path
+    assert_equal 'foo/posts#index', @response.body
+
+    get '/foo/posts/1'
+    assert_equal '/foo/posts/1', foo_post_path('1')
+    assert_equal 'foo/posts#show', @response.body
+
+    get '/foo/posts/1/comments'
+    assert_equal '/foo/posts/1/comments', foo_post_comments_path('1')
+    assert_equal 'foo/comments#index', @response.body
+
+    get '/foo/comments/2'
+    assert_equal '/foo/comments/2', bar_comment_path('2')
+    assert_equal 'foo/comments#show', @response.body
+  end
+
   def test_namespace_containing_numbers
     draw do
       namespace :v2 do