Improve cluster policy spec coverage

spec/policies/clusters/instance_policy_spec.rb

@@ -9,6 +9,8 @@ describe Clusters::InstancePolicy do
   describe 'rules' do
     context 'when user' do
       it { expect(policy).to be_disallowed :read_cluster }
+      it { expect(policy).to be_disallowed :add_cluster }
+      it { expect(policy).to be_disallowed :create_cluster }
       it { expect(policy).to be_disallowed :update_cluster }
       it { expect(policy).to be_disallowed :admin_cluster }
     end
@@ -17,6 +19,8 @@ describe Clusters::InstancePolicy do
       let(:user) { create(:admin) }
 
       it { expect(policy).to be_allowed :read_cluster }
+      it { expect(policy).to be_allowed :add_cluster }
+      it { expect(policy).to be_allowed :create_cluster }
       it { expect(policy).to be_allowed :update_cluster }
       it { expect(policy).to be_allowed :admin_cluster }
     end

spec/support/shared_examples/policies/clusterable_shared_examples.rb

@@ -13,7 +13,11 @@ shared_examples 'clusterable policies' do
         clusterable.add_developer(current_user)
       end
 
+      it { expect_disallowed(:read_cluster) }
       it { expect_disallowed(:add_cluster) }
+      it { expect_disallowed(:create_cluster) }
+      it { expect_disallowed(:update_cluster) }
+      it { expect_disallowed(:admin_cluster) }
     end
 
     context 'with a maintainer' do
@@ -22,7 +26,11 @@ shared_examples 'clusterable policies' do
       end
 
       context 'with no clusters' do
+        it { expect_allowed(:read_cluster) }
         it { expect_allowed(:add_cluster) }
+        it { expect_allowed(:create_cluster) }
+        it { expect_allowed(:update_cluster) }
+        it { expect_allowed(:admin_cluster) }
       end
     end
   end