Fix scaffold controller generator with namespace (#512)

* Fix scaffold controller generator with namespace

For example:

```
bundle exec rails g scaffold_controller Admin::Post title:string content:text --model-name=Post
```

It fixes the code generated by jbuilder, other changes are required on
railties gem.

* Specify main branch for rails-head

* Add test for controller scaffold with namespace

Only for Rails::VERSION::MAJOR >= 6 because the method `show_helper`
doesn't handle well the namespaces on previous versions.

Co-authored-by: David Heinemeier Hansson <david@basecamp.com>

lib/generators/rails/templates/controller.rb

@@ -30,7 +30,7 @@ def create
 
     respond_to do |format|
       if @<%= orm_instance.save %>
-        format.html { redirect_to @<%= singular_table_name %>, notice: <%= %("#{human_name} was successfully created.") %> }
+        format.html { redirect_to <%= show_helper %>, notice: <%= %("#{human_name} was successfully created.") %> }
         format.json { render :show, status: :created, location: <%= "@#{singular_table_name}" %> }
       else
         format.html { render :new, status: :unprocessable_entity }
@@ -43,7 +43,7 @@ def create
   def update
     respond_to do |format|
       if @<%= orm_instance.update("#{singular_table_name}_params") %>
-        format.html { redirect_to @<%= singular_table_name %>, notice: <%= %("#{human_name} was successfully updated.") %> }
+        format.html { redirect_to <%= show_helper %>, notice: <%= %("#{human_name} was successfully updated.") %> }
         format.json { render :show, status: :ok, location: <%= "@#{singular_table_name}" %> }
       else
         format.html { render :edit, status: :unprocessable_entity }

test/scaffold_controller_generator_test.rb

@@ -31,14 +31,14 @@ class ScaffoldControllerGeneratorTest < Rails::Generators::TestCase
       assert_instance_method :create, content do |m|
         assert_match %r{@post = Post\.new\(post_params\)}, m
         assert_match %r{@post\.save}, m
-        assert_match %r{format\.html \{ redirect_to @post, notice: "Post was successfully created\." \}}, m
+        assert_match %r{format\.html \{ redirect_to post_url\(@post\), notice: "Post was successfully created\." \}}, m
         assert_match %r{format\.json \{ render :show, status: :created, location: @post \}}, m
         assert_match %r{format\.html \{ render :new, status: :unprocessable_entity \}}, m
         assert_match %r{format\.json \{ render json: @post\.errors, status: :unprocessable_entity \}}, m
       end
 
       assert_instance_method :update, content do |m|
-        assert_match %r{format\.html \{ redirect_to @post, notice: "Post was successfully updated\." \}}, m
+        assert_match %r{format\.html \{ redirect_to post_url\(@post\), notice: "Post was successfully updated\." \}}, m
         assert_match %r{format\.json \{ render :show, status: :ok, location: @post \}}, m
         assert_match %r{format\.html \{ render :edit, status: :unprocessable_entity \}}, m
         assert_match %r{format\.json \{ render json: @post.errors, status: :unprocessable_entity \}}, m
@@ -59,6 +59,25 @@ class ScaffoldControllerGeneratorTest < Rails::Generators::TestCase
     end
   end
 
+  if Rails::VERSION::MAJOR >= 6
+    test 'controller with namespace' do
+      run_generator %w(Admin::Post --model-name=Post)
+      assert_file 'app/controllers/admin/posts_controller.rb' do |content|
+        assert_instance_method :create, content do |m|
+          assert_match %r{format\.html \{ redirect_to admin_post_url\(@post\), notice: "Post was successfully created\." \}}, m
+        end
+
+        assert_instance_method :update, content do |m|
+          assert_match %r{format\.html \{ redirect_to admin_post_url\(@post\), notice: "Post was successfully updated\." \}}, m
+        end
+
+        assert_instance_method :destroy, content do |m|
+          assert_match %r{format\.html \{ redirect_to admin_posts_url, notice: "Post was successfully destroyed\." \}}, m
+        end
+      end
+    end
+  end
+
   test "don't use require and permit if there are no attributes" do
     run_generator %w(Post)