Fix tests and rename request variable in specs to perform_request

Explanation: Using the variable name `request` might interfere with methods in Rails core system prevent successful test execution. See this issue: https://github.com/turbolinks/turbolinks-rails/issues/38

spec/policies/code_ocean/error_policy_spec.rb

@@ -0,0 +1,41 @@
+require 'rails_helper'
+
+describe CodeOcean::ErrorPolicy do
+  subject { described_class }
+
+  let(:error) { FactoryBot.build(:error) }
+
+  [:create?, :index?, :new?].each do |action|
+    permissions(action) do
+      it 'grants access to admins' do
+        expect(subject).to permit(FactoryBot.build(:admin), error)
+      end
+
+      it 'grants access to teachers' do
+        expect(subject).to permit(FactoryBot.build(:teacher), error)
+      end
+
+      it 'does not grant access to external users' do
+        expect(subject).not_to permit(FactoryBot.build(:external_user), error)
+      end
+    end
+  end
+
+  [:destroy?, :edit?, :show?, :update?].each do |action|
+    permissions(action) do
+      it 'grants access to admins' do
+        expect(subject).to permit(FactoryBot.build(:admin), error)
+      end
+
+      it 'grants access to authors' do
+        expect(subject).to permit(error.execution_environment.author, error)
+      end
+
+      it 'does not grant access to all other users' do
+        [:external_user, :teacher].each do |factory_name|
+          expect(subject).not_to permit(FactoryBot.build(factory_name), error)
+        end
+      end
+    end
+  end
+end