fix: Execute PAM authentication tests on CircleCI (#9029)

and use 'if' option of context block

.circleci/config.yml

@@ -13,6 +13,9 @@ aliases:
           ALLOW_NOPAM: true
           CONTINUOUS_INTEGRATION: true
           DISABLE_SIMPLECOV: true
+          PAM_ENABLED: true	
+          PAM_DEFAULT_SERVICE: pam_test	
+          PAM_CONTROLLED_SERVICE: pam_test_controlled
     working_directory: ~/projects/mastodon/
 
   - &attach_workspace

spec/controllers/auth/sessions_controller_spec.rb

@@ -55,8 +55,7 @@ RSpec.describe Auth::SessionsController, type: :controller do
       request.env['devise.mapping'] = Devise.mappings[:user]
     end
 
-    if ENV['PAM_ENABLED'] == 'true'
+    context 'using PAM authentication', if: ENV['PAM_ENABLED'] == 'true' do
-      context 'using PAM authentication' do
       context 'using a valid password' do
         before do
           post :create, params: { user: { email: "pam_user1", password: '123456' } }
@@ -106,7 +105,6 @@ RSpec.describe Auth::SessionsController, type: :controller do
         end
       end
     end
-    end
 
     context 'using password authentication' do
       let(:user) { Fabricate(:user, email: 'foo@bar.com', password: 'abcdefgh') }