From a3d957fa42d51c50d703691b2c44ba96b06605bf Mon Sep 17 00:00:00 2001
From: Nicholas Ward <npward@berkeley.edu>
Date: Mon, 1 Nov 2021 14:40:14 -0700
Subject: [PATCH] addressed comment: more tests for multiple_comparison

---
 src/gadgets/multiple_comparison.rs | 39 ++++++++++++------------------
 src/gates/subtraction_u32.rs       |  2 +-
 2 files changed, 16 insertions(+), 25 deletions(-)

diff --git a/src/gadgets/multiple_comparison.rs b/src/gadgets/multiple_comparison.rs
index 579708c8..4c928c11 100644
--- a/src/gadgets/multiple_comparison.rs
+++ b/src/gadgets/multiple_comparison.rs
@@ -74,7 +74,7 @@ mod tests {
     use crate::plonk::circuit_data::CircuitConfig;
     use crate::plonk::verifier::verify;
 
-    fn test_list_le(size: usize) -> Result<()> {
+    fn test_list_le(size: usize, num_bits: usize) -> Result<()> {
         type F = CrandallField;
         let config = CircuitConfig::large_config();
         let pw = PartialWitness::new();
@@ -82,26 +82,26 @@ mod tests {
 
         let mut rng = rand::thread_rng();
 
-        let lst1: Vec<u32> = (0..size).map(|_| rng.gen()).collect();
-        let lst2: Vec<u32> = (0..size)
+        let lst1: Vec<u64> = (0..size).map(|_| rng.gen_range(0..(1 << num_bits))).collect();
+        let lst2: Vec<u64> = (0..size)
             .map(|i| {
-                let mut res = rng.gen();
+                let mut res = rng.gen_range(0..(1 << num_bits));
                 while res <= lst1[i] {
-                    res = rng.gen();
+                    res = rng.gen_range(0..(1 << num_bits));
                 }
                 res
             })
             .collect();
         let a = lst1
             .iter()
-            .map(|&x| builder.constant(F::from_canonical_u32(x)))
+            .map(|&x| builder.constant(F::from_canonical_u64(x)))
             .collect();
         let b = lst2
             .iter()
-            .map(|&x| builder.constant(F::from_canonical_u32(x)))
+            .map(|&x| builder.constant(F::from_canonical_u64(x)))
             .collect();
 
-        let result = builder.list_le(a, b, 32);
+        let result = builder.list_le(a, b, num_bits);
 
         let expected_result = builder.constant_bool(true);
         builder.connect(result.target, expected_result.target);
@@ -112,22 +112,13 @@ mod tests {
     }
 
     #[test]
-    fn test_multiple_comparison_trivial() -> Result<()> {
-        test_list_le(1)
-    }
+    fn test_multiple_comparison() -> Result<()> {
+        for size in [1, 3, 6, 10] {
+            for num_bits in [20, 32, 40, 50] {
+                test_list_le(size, num_bits).unwrap();
+            }
+        }
 
-    #[test]
-    fn test_multiple_comparison_small() -> Result<()> {
-        test_list_le(3)
-    }
-
-    #[test]
-    fn test_multiple_comparison_medium() -> Result<()> {
-        test_list_le(6)
-    }
-
-    #[test]
-    fn test_multiple_comparison_large() -> Result<()> {
-        test_list_le(10)
+        Ok(())
     }
 }
diff --git a/src/gates/subtraction_u32.rs b/src/gates/subtraction_u32.rs
index b348b6f2..14447727 100644
--- a/src/gates/subtraction_u32.rs
+++ b/src/gates/subtraction_u32.rs
@@ -50,10 +50,10 @@ impl<F: RichField + Extendable<D>, const D: usize> U32SubtractionGate<F, D> {
         5 * i + 4
     }
 
-    // We have limbs ony for the first half of the output.
     pub fn limb_bits() -> usize {
         2
     }
+    // We have limbs for the 32 bits of `output_result`.
     pub fn num_limbs() -> usize {
         32 / Self::limb_bits()
     }