diff --git a/spec/models/submission_spec.rb b/spec/models/submission_spec.rb
index b55dedd2..fdba9c87 100644
--- a/spec/models/submission_spec.rb
+++ b/spec/models/submission_spec.rb
@@ -1,9 +1,7 @@
 require 'rails_helper'
 
 describe Submission do
-  before(:all) do
-    @submission = FactoryGirl.create(:submission)
-  end
+  let(:submission) { FactoryGirl.create(:submission, exercise: FactoryGirl.create(:dummy)) }
 
   it 'validates the presence of a cause' do
     expect(described_class.create.errors[:cause]).to be_present
@@ -20,11 +18,11 @@ describe Submission do
 
   [:download, :render, :run, :test].each do |action|
     describe "##{action}_url" do
-      let(:url) { @submission.send(:"#{action}_url") }
+      let(:url) { submission.send(:"#{action}_url") }
 
       it "starts like the #{action} path" do
         filename = File.basename(__FILE__)
-        expect(url).to start_with(Rails.application.routes.url_helpers.send(:"#{action}_submission_path", @submission, filename).sub(filename, ''))
+        expect(url).to start_with(Rails.application.routes.url_helpers.send(:"#{action}_submission_path", submission, filename).sub(filename, ''))
       end
 
       it 'ends with a placeholder' do
@@ -33,19 +31,83 @@ describe Submission do
     end
   end
 
+  describe '#main_file' do
+    let(:submission) { FactoryGirl.create(:submission) }
+
+    it "returns the submission's main file" do
+      expect(submission.main_file).to be_a(CodeOcean::File)
+      expect(submission.main_file.main_file?).to be true
+    end
+  end
+
+  describe '#normalized_score' do
+    context 'with a score' do
+      let(:submission) { FactoryGirl.create(:submission) }
+      before(:each) { submission.score = submission.exercise.maximum_score / 2 }
+
+      it 'returns the score as a value between 0 and 1' do
+        expect(0..1).to include(submission.normalized_score)
+      end
+    end
+
+    context 'without a score' do
+      before(:each) { submission.score = nil }
+
+      it 'returns nil' do
+        expect(submission.normalized_score).to be nil
+      end
+    end
+  end
+
+  describe '#percentage' do
+    context 'with a score' do
+      let(:submission) { FactoryGirl.create(:submission) }
+      before(:each) { submission.score = submission.exercise.maximum_score / 2 }
+
+      it 'returns the score expressed as a percentage' do
+        expect(0..100).to include(submission.percentage)
+      end
+    end
+
+    context 'without a score' do
+      before(:each) { submission.score = nil }
+
+      it 'returns nil' do
+        expect(submission.percentage).to be nil
+      end
+    end
+  end
+
   [:score, :stop].each do |action|
     describe "##{action}_url" do
-      let(:url) { @submission.send(:"#{action}_url") }
+      let(:url) { submission.send(:"#{action}_url") }
 
       it "corresponds to the #{action} path" do
-        expect(url).to eq(Rails.application.routes.url_helpers.send(:"#{action}_submission_path", @submission))
+        expect(url).to eq(Rails.application.routes.url_helpers.send(:"#{action}_submission_path", submission))
       end
     end
   end
 
+  describe '#siblings' do
+    let(:siblings) { described_class.find_by(user: user).siblings }
+    let(:user) { FactoryGirl.create(:external_user) }
+
+    before(:each) do
+      10.times.each_with_index do |_, index|
+        FactoryGirl.create(:submission, exercise: submission.exercise, user: (index.even? ? user : FactoryGirl.create(:external_user)))
+      end
+    end
+
+    it "returns all the creator's submissions for the same exercise" do
+      expect(siblings).to be_an(ActiveRecord::Relation)
+      expect(siblings.map(&:exercise).uniq).to eq([submission.exercise])
+      expect(siblings.map(&:user).uniq).to eq([user])
+    end
+  end
+
   describe '#to_s' do
     it "equals the class' model name" do
-      expect(@submission.to_s).to eq(described_class.model_name.human)
+      expect(submission.to_s).to eq(described_class.model_name.human)
     end
   end
 end