fix: Identity JSON response header (#6326)

app/controllers/microsoft_controller.rb

@@ -1,5 +1,17 @@
 class MicrosoftController < ApplicationController
+  after_action :set_version_header
+
   def identity_association
-    render layout: false
+    microsoft_indentity
+  end
+
+  private
+
+  def set_version_header
+    response.headers['Content-Length'] = { associatedApplications: [{ applicationId: @identity_json }] }.to_json.length
+  end
+
+  def microsoft_indentity
+    @identity_json = ENV.fetch('AZURE_APP_ID', nil)
   end
 end

app/views/microsoft/identity_association.json.jbuilder

@@ -0,0 +1,5 @@
+json.associatedApplications do
+  json.array! [@identity_json] do |identity_id|
+    json.applicationId identity_id
+  end
+end

spec/controllers/microsoft_controller_spec.rb

@@ -6,7 +6,11 @@
       with_modified_env AZURE_APP_ID: 'azure-application-client-id' do
         get '/.well-known/microsoft-identity-association.json'
         expect(response).to have_http_status(:success)
-        expect(response.body).to include '"applicationId":  "azure-application-client-id"'
+        expect(response.body).to include '"applicationId":"azure-application-client-id"'
+
+        content_length = { associatedApplications: [{ applicationId: 'azure-application-client-id' }] }.to_json.length
+
+        expect(response.headers['Content-Length']).to eq(content_length.to_s)
       end
     end
   end