From 31cbe96371d9800655f585e8bca44f4d25c5aedb Mon Sep 17 00:00:00 2001
From: David Cook <dcook@divviup.org>
Date: Thu, 25 Jul 2024 09:15:58 -0500
Subject: [PATCH] Add a broad range check to DP integration tests

---
 integration_tests/tests/integration/in_cluster.rs | 9 +++++++++
 integration_tests/tests/integration/janus.rs      | 9 +++++++++
 2 files changed, 18 insertions(+)

diff --git a/integration_tests/tests/integration/in_cluster.rs b/integration_tests/tests/integration/in_cluster.rs
index a31b5bb88..93d9e251f 100644
--- a/integration_tests/tests/integration/in_cluster.rs
+++ b/integration_tests/tests/integration/in_cluster.rs
@@ -33,6 +33,7 @@ use prio::{
     dp::{
         distributions::PureDpDiscreteLaplace, DifferentialPrivacyStrategy, PureDpBudget, Rational,
     },
+    field::{Field128, FieldElementWithInteger},
     vdaf::prio3::Prio3,
 };
 use std::{env, iter, str::FromStr, time::Duration};
@@ -977,6 +978,10 @@ async fn in_cluster_histogram_dp_noise() {
     // large (drawn from Laplace_Z(20) + Laplace_Z(20)), and it is highly unlikely that all 100
     // noise values will be zero simultaneously.
     assert_ne!(aggregate_result, un_noised_result);
+
+    assert!(aggregate_result
+        .iter()
+        .all(|x| *x < Field128::modulus() / 4 || *x > Field128::modulus() / 4 * 3));
 }
 
 #[tokio::test(flavor = "multi_thread")]
@@ -1041,4 +1046,8 @@ async fn in_cluster_sumvec_dp_noise() {
     // large (drawn from Laplace_Z(150) + Laplace_Z(150)), and it is highly unlikely that all 50
     // noise values will be zero simultaneously.
     assert_ne!(aggregate_result, un_noised_result);
+
+    assert!(aggregate_result
+        .iter()
+        .all(|x| *x < Field128::modulus() / 4 || *x > Field128::modulus() / 4 * 3));
 }
diff --git a/integration_tests/tests/integration/janus.rs b/integration_tests/tests/integration/janus.rs
index 82be09a84..1b8e55f52 100644
--- a/integration_tests/tests/integration/janus.rs
+++ b/integration_tests/tests/integration/janus.rs
@@ -22,6 +22,7 @@ use prio::{
     dp::{
         distributions::PureDpDiscreteLaplace, DifferentialPrivacyStrategy, PureDpBudget, Rational,
     },
+    field::{Field128, FieldElementWithInteger},
     vdaf::{dummy, prio3::Prio3},
 };
 use std::{iter, time::Duration};
@@ -514,6 +515,10 @@ async fn janus_in_process_histogram_dp_noise() {
     // large (drawn from Laplace_Z(20) + Laplace_Z(20)), and it is highly unlikely that all 100
     // noise values will be zero simultaneously.
     assert_ne!(aggregate_result, un_noised_result);
+
+    assert!(aggregate_result
+        .iter()
+        .all(|x| *x < Field128::modulus() / 4 || *x > Field128::modulus() / 4 * 3));
 }
 
 #[tokio::test(flavor = "multi_thread")]
@@ -574,4 +579,8 @@ async fn janus_in_process_sumvec_dp_noise() {
     // large (drawn from Laplace_Z(150) + Laplace_Z(150)), and it is highly unlikely that all 50
     // noise values will be zero simultaneously.
     assert_ne!(aggregate_result, un_noised_result);
+
+    assert!(aggregate_result
+        .iter()
+        .all(|x| *x < Field128::modulus() / 4 || *x > Field128::modulus() / 4 * 3));
 }