Fix in models/exercise_spec.rb, repair average_percentage without submission

.rspec

@@ -1,2 +1,6 @@
 --color
 --format NyanCatWideFormatter
+
+--require spec_helper
+--order random
+--format documentation

Gemfile

@@ -49,12 +49,12 @@ group :development do
   gem 'capistrano-upload-config'
   gem 'rubocop', require: false
   gem 'rubocop-rspec'
+  gem 'web-console', '~> 2.0', platform: :ruby
 end
 
 group :development, :test do
   gem 'byebug', platform: :ruby
   gem 'spring'
-  gem 'web-console', '~> 2.0', platform: :ruby
 end
 
 group :test do

app/models/exercise.rb

@@ -30,7 +30,7 @@ class Exercise < ActiveRecord::Base
 
 
   def average_percentage
-    if average_score and maximum_score != 0.0
+    if average_score and maximum_score != 0.0 and submissions.exists?(cause: 'submit')
       (average_score / maximum_score * 100).round
     else
       0

spec/models/execution_environment_spec.rb

@@ -121,7 +121,7 @@ describe ExecutionEnvironment do
 
   describe '#working_docker_image?', docker: true do
     let(:working_docker_image?) { execution_environment.send(:working_docker_image?) }
-    before(:each) { expect(DockerClient).to receive(:find_image_by_tag).and_return(Object.new) }
+    before(:each) { expect(DockerClient).to receive(:find_image_by_tag) }
 
     it 'instantiates a Docker client' do
       expect(DockerClient).to receive(:new).with(execution_environment: execution_environment).and_call_original

spec/models/exercise_spec.rb

@@ -50,7 +50,7 @@ describe Exercise do
 
     context 'without submissions' do
       it 'returns nil' do
-        expect(exercise.average_percentage).to be nil
+        expect(exercise.average_percentage).to be 0
       end
     end
 

spec/spec_helper.rb

@@ -33,6 +33,11 @@ RSpec.configure do |config|
   config.filter_run :focus
   config.run_all_when_everything_filtered = true
 
+
+  #for --next-failure feature purpose
+  config.example_status_persistence_file_path = "examples.txt"
+  config.run_all_when_everything_filtered = true
+
   # Many RSpec users commonly either run the entire suite or an individual
   # file, and it's useful to allow more verbose output when running an
   # individual spec file.