diff --git a/test/integration/api/domain_admin_contacts_test.rb b/test/integration/api/domain_admin_contacts_test.rb
new file mode 100644
index 000000000..75b58d318
--- /dev/null
+++ b/test/integration/api/domain_admin_contacts_test.rb
@@ -0,0 +1,115 @@
+require 'test_helper'
+
+class APIDomainAdminContactsTest < ApplicationIntegrationTest
+  def test_replace_all_admin_contacts_of_the_current_registrar
+    patch '/repp/v1/domains/admin_contacts', params: { current_contact_id: 'william-001',
+                                                 new_contact_id: 'john-001' },
+          headers: { 'HTTP_AUTHORIZATION' => http_auth_key }
+
+    assert_nil domains(:shop).admin_contacts.find_by(code: 'william-001')
+    assert domains(:shop).admin_contacts.find_by(code: 'john-001')
+    assert domains(:airport).admin_contacts.find_by(code: 'john-001')
+  end
+
+  def test_skip_discarded_domains
+    domains(:airport).update!(statuses: [DomainStatus::DELETE_CANDIDATE])
+
+    patch '/repp/v1/domains/admin_contacts', params: { current_contact_id: 'william-001',
+                                                 new_contact_id: 'john-001' },
+          headers: { 'HTTP_AUTHORIZATION' => http_auth_key }
+
+    assert domains(:airport).admin_contacts.find_by(code: 'william-001')
+  end
+
+  def test_return_affected_domains_in_alphabetical_order
+    patch '/repp/v1/domains/admin_contacts', params: { current_contact_id: 'william-001',
+                                                 new_contact_id: 'john-001' },
+          headers: { 'HTTP_AUTHORIZATION' => http_auth_key }
+
+    assert_response :ok
+    assert_equal ({ code: 1000, message: 'Command completed successfully', data: { affected_domains: %w[airport.test shop.test],
+                    skipped_domains: [] }}),
+                 JSON.parse(response.body, symbolize_names: true)
+  end
+
+  def test_return_skipped_domains_in_alphabetical_order
+    domains(:shop).update!(statuses: [DomainStatus::DELETE_CANDIDATE])
+    domains(:airport).update!(statuses: [DomainStatus::DELETE_CANDIDATE])
+
+    patch '/repp/v1/domains/admin_contacts', params: { current_contact_id: 'william-001',
+                                                 new_contact_id: 'john-001' },
+          headers: { 'HTTP_AUTHORIZATION' => http_auth_key }
+
+    assert_response :ok
+    assert_equal %w[airport.test shop.test], JSON.parse(response.body,
+                                                        symbolize_names: true)[:data][:skipped_domains]
+  end
+
+  def test_keep_other_admin_contacts_intact
+    patch '/repp/v1/domains/admin_contacts', params: { current_contact_id: 'william-001',
+                                                 new_contact_id: 'john-001' },
+          headers: { 'HTTP_AUTHORIZATION' => http_auth_key }
+
+    assert domains(:shop).admin_contacts.find_by(code: 'acme-ltd-001')
+  end
+
+  def test_keep_tech_contacts_intact
+    patch '/repp/v1/domains/admin_contacts', params: { current_contact_id: 'william-001',
+                                                 new_contact_id: 'john-001' },
+          headers: { 'HTTP_AUTHORIZATION' => http_auth_key }
+
+    assert domains(:airport).tech_contacts.find_by(code: 'william-001')
+  end
+
+  def test_restrict_contacts_to_the_current_registrar
+    patch '/repp/v1/domains/admin_contacts', params: { current_contact_id: 'jack-001',
+                                                 new_contact_id: 'william-002' },
+          headers: { 'HTTP_AUTHORIZATION' => http_auth_key }
+
+    assert_response :not_found
+    assert_equal ({ code: 2303, message: 'Object does not exist' }),
+                 JSON.parse(response.body, symbolize_names: true)
+  end
+
+  def test_non_existent_current_contact
+    patch '/repp/v1/domains/admin_contacts', params: { current_contact_id: 'non-existent',
+                                                 new_contact_id: 'john-001' },
+          headers: { 'HTTP_AUTHORIZATION' => http_auth_key }
+    assert_response :not_found
+    assert_equal ({ code: 2303, message: 'Object does not exist' }),
+                 JSON.parse(response.body, symbolize_names: true)
+  end
+
+  def test_non_existent_new_contact
+    patch '/repp/v1/domains/admin_contacts', params: { current_contact_id: 'william-001',
+                                                 new_contact_id: 'non-existent' },
+          headers: { 'HTTP_AUTHORIZATION' => http_auth_key }
+    assert_response :not_found
+    assert_equal ({code: 2303, message: 'Object does not exist'}),
+                 JSON.parse(response.body, symbolize_names: true)
+  end
+
+  def test_disallow_invalid_new_contact
+    patch '/repp/v1/domains/admin_contacts', params: { current_contact_id: 'william-001',
+                                                 new_contact_id: 'invalid' },
+          headers: { 'HTTP_AUTHORIZATION' => http_auth_key }
+    assert_response :bad_request
+    assert_equal ({ code: 2304, message: 'New contact must be valid', data: {} }),
+                 JSON.parse(response.body, symbolize_names: true)
+  end
+
+  def test_disallow_self_replacement
+    patch '/repp/v1/domains/admin_contacts', params: { current_contact_id: 'william-001',
+                                                 new_contact_id: 'william-001' },
+          headers: { 'HTTP_AUTHORIZATION' => http_auth_key }
+    assert_response :bad_request
+    assert_equal ({ code: 2304, message: 'New contact must be different from current', data: {} }),
+                 JSON.parse(response.body, symbolize_names: true)
+  end
+
+  private
+
+  def http_auth_key
+    ActionController::HttpAuthentication::Basic.encode_credentials('test_bestnames', 'testtest')
+  end
+end