Simplify permission specs

* Remove iteration if not required
* Unify usage of parentheses for `permissions` call

spec/policies/codeharbor_link_policy_spec.rb

@@ -54,7 +54,7 @@ describe CodeharborLinkPolicy do
       end
     end
 
-    permissions(:enabled?) do
+    permissions :enabled? do
       it 'reflects the config option' do
         %i[external_user admin teacher].each do |factory_name|
           expect(policy).to permit(create(factory_name), codeharbor_link)
@@ -72,7 +72,7 @@ describe CodeharborLinkPolicy do
       allow(codeocean_config).to receive(:read).and_return(codeharbor_config)
     end
 
-    permissions(:enabled?) do
+    permissions :enabled? do
       it 'reflects the config option' do
         %i[external_user admin teacher].each do |factory_name|
           expect(policy).not_to permit(create(factory_name), codeharbor_link)

spec/policies/execution_environment_policy_spec.rb

@@ -7,8 +7,7 @@ describe ExecutionEnvironmentPolicy do
 
   let(:execution_environment) { build(:ruby) }
 
-  [:index?].each do |action|
-    permissions(action) do
+  permissions :index? do
     it 'grants access to admins' do
       expect(policy).to permit(build(:admin), execution_environment)
     end
@@ -21,7 +20,6 @@ describe ExecutionEnvironmentPolicy do
       expect(policy).not_to permit(build(:external_user), execution_environment)
     end
   end
-  end
 
   %i[execute_command? shell? statistics? show?].each do |action|
     permissions(action) do
@@ -59,7 +57,7 @@ describe ExecutionEnvironmentPolicy do
     end
   end
 
-  permissions(:sync_all_to_runner_management?) do
+  permissions :sync_all_to_runner_management? do
     it 'grants access to the admin' do
       expect(policy).to permit(build(:admin))
     end

spec/policies/exercise_policy_spec.rb

@@ -104,26 +104,21 @@ describe ExercisePolicy do
     end
   end
 
-  [:show?].each do |action|
-    permissions(action) do
+  permissions :show? do
     it 'not grants access to external users' do
       expect(policy).not_to permit(build(:external_user), exercise)
     end
   end
-  end
 
-  %i[implement?].each do |action|
-    permissions(action) do
+  permissions :implement? do
     it 'grants access to anyone' do
       %i[admin external_user teacher].each do |factory_name|
         expect(policy).to permit(build(factory_name), Exercise.new)
       end
     end
   end
-  end
 
-  %i[submit?].each do |action|
-    permissions(action) do
+  permissions :submit? do
     context 'when teacher-defined assessments are available' do
       before { create(:test_file, context: exercise) }
 
@@ -142,7 +137,6 @@ describe ExercisePolicy do
       end
     end
   end
-  end
 
   describe ExercisePolicy::Scope do
     describe '#resolve' do

spec/policies/external_user_policy_spec.rb

@@ -16,8 +16,7 @@ describe ExternalUserPolicy do
     end
   end
 
-  [:index?].each do |action|
-    permissions(action) do
+  permissions :index? do
     it 'grants access to admins and teachers only' do
       expect(policy).to permit(build(:admin), ExternalUser.new)
       expect(policy).to permit(build(:teacher), ExternalUser.new)
@@ -27,4 +26,3 @@ describe ExternalUserPolicy do
     end
   end
 end
-end