package api

import "testing"

// FLEX-DEC-2026-019: purpose is hashed when set and absent when empty, so an
// enforcement digest is unchanged and a readback digest can never equal one.
func TestPurposeEntersDigestsOnlyWhenSet(t *testing.T) {
	request := CheckRequest{
		Subject:  SubjectRef{ID: "user:alice"},
		Action:   "application.access",
		Resource: ResourceRef{ID: "demo-app", System: "demo-app"},
	}
	legacy := CanonicalDigest(requestDigestMaterial{Subject: request.Subject, Action: request.Action, Resource: request.Resource})
	if RequestDigest(request) != legacy {
		t.Fatal("an empty purpose changed the enforcement digest")
	}
	readback := request
	readback.Purpose = PurposeReadback
	if RequestDigest(readback) == RequestDigest(request) || ApprovalBindingDigest(readback) == ApprovalBindingDigest(request) {
		t.Fatal("purpose did not enter the digests")
	}
	if binding := NewDecisionBinding(readback); binding.Purpose != PurposeReadback {
		t.Fatalf("binding purpose = %q", binding.Purpose)
	}
}