Fix rubocop errors

Author: phrdang

src/app/server/Gemfile

@@ -35,7 +35,7 @@ gem "thruster", require: false
 # Use Rack CORS for handling Cross-Origin Resource Sharing (CORS), making cross-origin Ajax possible
 # gem "rack-cors"
 
-gem 'aws-sdk-s3'
+gem "aws-sdk-s3"
 
 group :development, :test do
   # See https://guides.rubyonrails.org/debugging_rails_applications.html#debugging-with-the-debug-gem

src/app/server/app/controllers/files_controller.rb

@@ -1,13 +1,13 @@
-require 'aws-sdk-s3'
+require "aws-sdk-s3"
 
-S3_BUCKET_NAME = 'ucb-assignment-snapshots-eae254943a2c4f51bef67654e99560dd'
-S3_BUCKET_REGION = 'us-west-2'
+S3_BUCKET_NAME = "ucb-assignment-snapshots-eae254943a2c4f51bef67654e99560dd"
+S3_BUCKET_REGION = "us-west-2"
 
 class FilesController < ApplicationController
   def get_object_key(params)
     # NOTE: we assume the okpy endpoint is passed in with - as the separator since / is reserved
-    okpy_endpoint_parsed = params[:okpy_endpoint].gsub('-', '/')
-    return "#{okpy_endpoint_parsed}/#{params[:assignment]}/#{params[:student_id]}/#{params[:backup_id]}/#{params[:file_name]}"
+    okpy_endpoint_parsed = params[:okpy_endpoint].gsub("-", "/")
+    "#{okpy_endpoint_parsed}/#{params[:assignment]}/#{params[:student_id]}/#{params[:backup_id]}/#{params[:file_name]}"
   end
 
   def show
@@ -22,7 +22,7 @@ def show
 
     begin
       resp = s3.get_object(bucket: S3_BUCKET_NAME, key: object_key)
-      file_contents = resp.body.read.force_encoding('UTF-8') # Assuming UTF-8 encoding
+      file_contents = resp.body.read.force_encoding("UTF-8") # Assuming UTF-8 encoding
       status = :ok
     rescue Aws::S3::Errors::NoSuchBucket => e
       error = "Error: Bucket not found: #{bucket_name}"

src/app/server/test/controllers/files_controller_test.rb

@@ -1,8 +1,8 @@
 require "ostruct"
-require 'stringio'
+require "stringio"
 require "test_helper"
 
-require_relative '../../app/controllers/files_controller'
+require_relative "../../app/controllers/files_controller"
 
 class FilesControllerTest < ActionDispatch::IntegrationTest
   raw_okpy_endpoint = "cal-cs88-sp25"
@@ -11,15 +11,15 @@ class FilesControllerTest < ActionDispatch::IntegrationTest
   backup_id = "def456"
   route_prefix = "/files/#{raw_okpy_endpoint}/#{assignment}/#{student_id}/#{backup_id}"
   unknown_file = "unknown.txt"
-  known_files = ["utils.py", "abstractions.py", "recommend.py", "autograder_output.txt"]
-  file_contents = ["foo", "bar", "baz", "qux"]
+  known_files = [ "utils.py", "abstractions.py", "recommend.py", "autograder_output.txt" ]
+  file_contents = [ "foo", "bar", "baz", "qux" ]
 
   test "should respond with 404 Not Found if file name unknown" do
     # Mock AWS S3 client
     Aws::S3::Client.any_instance
       .stubs(:get_object)
       .with(bucket: S3_BUCKET_NAME, key: "cal/cs88/sp25/#{assignment}/#{student_id}/#{backup_id}/#{unknown_file}")
-      .raises(Aws::S3::Errors::NoSuchKey.new(nil, 'The specified key does not exist.'))
+      .raises(Aws::S3::Errors::NoSuchKey.new(nil, "The specified key does not exist."))
 
     get "#{route_prefix}/#{unknown_file}"
     assert_response :missing

src/app/server/test/test_helper.rb

@@ -1,7 +1,7 @@
 ENV["RAILS_ENV"] ||= "test"
 require_relative "../config/environment"
 require "rails/test_help"
-require 'mocha/minitest'
+require "mocha/minitest"
 
 module ActiveSupport
   class TestCase