fixed multiple style guide violations

app/controllers/concerns/common_behavior.rb

@@ -1,5 +1,5 @@
 module CommonBehavior
-  def create_and_respond(options = {}, &block)
+  def create_and_respond(options = {})
     @object = options[:object]
     respond_to do |format|
       if @object.save

app/controllers/concerns/submission_parameters.rb

@@ -2,8 +2,8 @@ module SubmissionParameters
   include FileParameters
 
   def reject_illegal_file_attributes!(submission_params)
-    if exercise = Exercise.find_by(id: submission_params[:exercise_id])
-      submission_params[:files_attributes].try(:reject!) do |index, file_attributes|
+    if Exercise.exists?(id: submission_params[:exercise_id])
+      submission_params[:files_attributes].try(:reject!) do |_, file_attributes|
         file = CodeOcean::File.find_by(id: file_attributes[:file_id])
         file.nil? || file.hidden || file.read_only
       end

app/controllers/execution_environments_controller.rb

@@ -24,7 +24,7 @@ class ExecutionEnvironmentsController < ApplicationController
   end
 
   def execute_command
-    @docker_client = DockerClient.new(execution_environment: @execution_environment, user: current_user)
+    @docker_client = DockerClient.new(execution_environment: @execution_environment)
     render(json: @docker_client.execute_arbitrary_command(params[:command]))
   end
 

app/controllers/sessions_controller.rb

@@ -9,7 +9,7 @@ class SessionsController < ApplicationController
   skip_before_action :verify_authenticity_token, only: :create_through_lti
 
   def create
-    if user = login(params[:email], params[:password], params[:remember_me])
+    if login(params[:email], params[:password], params[:remember_me])
       redirect_back_or_to(:root, notice: t('.success'))
     else
       flash.now[:danger] = t('.failure')

app/controllers/submissions_controller.rb

@@ -72,7 +72,7 @@ class SubmissionsController < ApplicationController
   end
 
   def set_docker_client
-    @docker_client = DockerClient.new(execution_environment: @submission.execution_environment, user: current_user)
+    @docker_client = DockerClient.new(execution_environment: @submission.execution_environment)
   end
   private :set_docker_client