Add update validation same as creation endpoints

src/main/kotlin/uk/gov/justice/digital/hmpps/personalrelationships/service/ContactIdentityService.kt

@@ -89,6 +89,15 @@ class ContactIdentityService(
   fun update(contactId: Long, contactIdentityId: Long, request: UpdateIdentityRequest, user: User): ContactIdentityDetails {
     validateContactExists(contactId)
     val existing = validateExistingIdentity(contactIdentityId)
+
+    val duplicateExisting = contactIdentityRepository.findByContactId(contactId)
+      .filter { it.contactIdentityId != contactIdentityId }
+      .any { it.identityType == request.identityType && it.identityValue == request.identityValue }
+
+    if (duplicateExisting) {
+      throw DuplicateIdentityDocumentException(request.identityType, request.identityValue)
+    }
+
     val type = referenceCodeService.validateReferenceCode(ReferenceCodeGroup.ID_TYPE, request.identityType, allowInactive = true)
     validatePNC(request.identityType, request.identityValue)
 

src/test/kotlin/uk/gov/justice/digital/hmpps/personalrelationships/integration/resource/UpdateContactIdentityIntegrationTest.kt

@@ -189,6 +189,35 @@ class UpdateContactIdentityIntegrationTest : SecureAPIIntegrationTestBase() {
     stubEvents.assertHasNoEvents(OutboundEvent.CONTACT_IDENTITY_UPDATED)
   }
 
+  @Test
+  fun `should not update the identity if another document exists with same type and value`() {
+    val documentToUpdate = testAPIClient.createAContactIdentity(
+      savedContactId,
+      CreateIdentityRequest(
+        identityType = "PASS",
+        identityValue = "9887676",
+        issuingAuthority = null,
+      ),
+    )
+    val request = aMinimalRequest()
+
+    val errors = webTestClient.put()
+      .uri("/contact/$savedContactId/identity/${documentToUpdate.contactIdentityId}")
+      .accept(MediaType.APPLICATION_JSON)
+      .contentType(MediaType.APPLICATION_JSON)
+      .headers(setAuthorisationUsingCurrentUser())
+      .bodyValue(request)
+      .exchange()
+      .expectStatus()
+      .is4xxClientError
+      .expectHeader().contentType(MediaType.APPLICATION_JSON)
+      .expectBody(ErrorResponse::class.java)
+      .returnResult().responseBody!!
+
+    assertThat(errors.userMessage).isEqualTo("Contact already has an identity document matching type \"DL\" and value \"DL123456789\"")
+    stubEvents.assertHasNoEvents(OutboundEvent.CONTACT_IDENTITY_UPDATED)
+  }
+
   @Test
   fun `should update the identity with minimal fields`() {
     val request = UpdateIdentityRequest(