From 6aee6d63182e99f4a5981c666bdeef662da3fd98 Mon Sep 17 00:00:00 2001
From: Stephen Waits <steve@waits.net>
Date: Thu, 14 May 2026 01:53:24 -0600
Subject: [PATCH] style: rustfmt the Phase 1 test additions
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The per-file Phase 1 test commits were written without running rustfmt
as I went; this pass formats the new test code (long assert_eq! lines
wrapped, etc.). Formatting-only — no behavioural change.
---
 examples/btsp_kroab.rs              | 66 ++++++++++++++++++------
 examples/mo_knapsack.rs             | 56 ++++++++++++---------
 examples/tsp_operators_compare.rs   | 78 +++++++++++++++++++++--------
 examples/tsp_ulysses16.rs           |  5 +-
 src/algorithms/age_moea.rs          | 23 +++++++--
 src/algorithms/bayesian_opt.rs      |  5 +-
 src/algorithms/cma_es.rs            | 40 ++++++++++++---
 src/algorithms/genetic_algorithm.rs | 15 ++++--
 src/algorithms/grea.rs              |  7 ++-
 src/algorithms/hill_climber.rs      | 10 +++-
 src/algorithms/hype.rs              |  5 +-
 src/algorithms/hyperband.rs         | 25 +++++++--
 src/algorithms/ibea.rs              |  5 +-
 src/algorithms/mopso.rs             | 12 ++++-
 src/algorithms/nelder_mead.rs       | 20 ++++++--
 src/algorithms/paes.rs              | 18 +++++--
 src/algorithms/pesa2.rs             |  5 +-
 src/algorithms/random_search.rs     |  6 ++-
 src/algorithms/rvea.rs              |  5 +-
 src/algorithms/snes.rs              | 15 ++++--
 src/algorithms/umda.rs              | 20 ++++++--
 src/explorer/mod.rs                 | 55 ++++++++++++--------
 src/metrics/hypervolume.rs          | 20 ++++----
 src/metrics/spacing.rs              |  5 +-
 src/operators/permutation.rs        | 10 +++-
 src/operators/real.rs               | 22 +++++---
 src/pareto/archive.rs               | 10 +++-
 src/pareto/crowding.rs              | 12 ++++-
 src/selection/tournament.rs         | 52 +++++++++++++++----
 29 files changed, 466 insertions(+), 161 deletions(-)

diff --git a/examples/btsp_kroab.rs b/examples/btsp_kroab.rs
index 3cf8906..e65b8bb 100644
--- a/examples/btsp_kroab.rs
+++ b/examples/btsp_kroab.rs
@@ -33,23 +33,59 @@ use heuropt::prelude::*;
 
 /// First 25 cities of TSPLIB KroA100 (EUC_2D).
 const KROA_25: [(f64, f64); 25] = [
-    (1380.0, 939.0), (2848.0, 96.0),  (3510.0, 1671.0), (457.0, 334.0),
-    (3888.0, 666.0), (984.0, 965.0),  (2721.0, 1482.0), (1286.0, 525.0),
-    (2716.0, 1432.0),(738.0, 1325.0), (1251.0, 1832.0), (2728.0, 1698.0),
-    (3815.0, 169.0), (3683.0, 1533.0),(1247.0, 1945.0), (123.0, 862.0),
-    (1234.0, 1946.0),(252.0, 1240.0), (611.0, 673.0),   (2576.0, 1676.0),
-    (928.0, 1700.0), (53.0, 857.0),   (1807.0, 1711.0), (274.0, 1420.0),
+    (1380.0, 939.0),
+    (2848.0, 96.0),
+    (3510.0, 1671.0),
+    (457.0, 334.0),
+    (3888.0, 666.0),
+    (984.0, 965.0),
+    (2721.0, 1482.0),
+    (1286.0, 525.0),
+    (2716.0, 1432.0),
+    (738.0, 1325.0),
+    (1251.0, 1832.0),
+    (2728.0, 1698.0),
+    (3815.0, 169.0),
+    (3683.0, 1533.0),
+    (1247.0, 1945.0),
+    (123.0, 862.0),
+    (1234.0, 1946.0),
+    (252.0, 1240.0),
+    (611.0, 673.0),
+    (2576.0, 1676.0),
+    (928.0, 1700.0),
+    (53.0, 857.0),
+    (1807.0, 1711.0),
+    (274.0, 1420.0),
     (2574.0, 946.0),
 ];
 
 /// First 25 cities of TSPLIB KroB100 (EUC_2D).
 const KROB_25: [(f64, f64); 25] = [
-    (3140.0, 1401.0),(556.0, 1056.0), (3675.0, 1522.0), (1182.0, 1853.0),
-    (3595.0, 1340.0),(1936.0, 953.0), (2722.0, 1311.0), (2839.0, 2055.0),
-    (2253.0, 1242.0),(3142.0, 1591.0),(627.0, 1336.0),  (936.0, 211.0),
-    (4014.0, 471.0), (1376.0, 1452.0),(3289.0, 593.0),  (1453.0, 67.0),
-    (1014.0, 1944.0),(2811.0, 1080.0),(3010.0, 1290.0), (1817.0, 1517.0),
-    (510.0, 458.0),  (1717.0, 1693.0),(1252.0, 1633.0), (1693.0, 1374.0),
+    (3140.0, 1401.0),
+    (556.0, 1056.0),
+    (3675.0, 1522.0),
+    (1182.0, 1853.0),
+    (3595.0, 1340.0),
+    (1936.0, 953.0),
+    (2722.0, 1311.0),
+    (2839.0, 2055.0),
+    (2253.0, 1242.0),
+    (3142.0, 1591.0),
+    (627.0, 1336.0),
+    (936.0, 211.0),
+    (4014.0, 471.0),
+    (1376.0, 1452.0),
+    (3289.0, 593.0),
+    (1453.0, 67.0),
+    (1014.0, 1944.0),
+    (2811.0, 1080.0),
+    (3010.0, 1290.0),
+    (1817.0, 1517.0),
+    (510.0, 458.0),
+    (1717.0, 1693.0),
+    (1252.0, 1633.0),
+    (1693.0, 1374.0),
     (539.0, 1378.0),
 ];
 
@@ -182,6 +218,8 @@ fn main() {
     let owned: Vec<Candidate<Vec<usize>>> = result.pareto_front.to_vec();
     let hv = hypervolume_2d(&owned, &problem.objectives(), ref_point);
     println!();
-    println!("Hypervolume vs. reference ({}, {}): {:.0}",
-        ref_point[0], ref_point[1], hv);
+    println!(
+        "Hypervolume vs. reference ({}, {}): {:.0}",
+        ref_point[0], ref_point[1], hv
+    );
 }
diff --git a/examples/mo_knapsack.rs b/examples/mo_knapsack.rs
index 567cf28..33ac032 100644
--- a/examples/mo_knapsack.rs
+++ b/examples/mo_knapsack.rs
@@ -39,24 +39,21 @@ const N_ITEMS: usize = 30;
 
 /// Profit vector A (one of two objectives), U(10, 100) style.
 const PROFITS_A: [f64; N_ITEMS] = [
-    61.0, 17.0, 92.0, 49.0, 73.0, 28.0, 84.0, 36.0, 55.0, 78.0,
-    23.0, 91.0, 12.0, 67.0, 45.0, 58.0, 33.0, 71.0, 14.0, 26.0,
-    87.0, 42.0, 19.0, 65.0, 30.0, 51.0, 79.0, 22.0, 47.0, 88.0,
+    61.0, 17.0, 92.0, 49.0, 73.0, 28.0, 84.0, 36.0, 55.0, 78.0, 23.0, 91.0, 12.0, 67.0, 45.0, 58.0,
+    33.0, 71.0, 14.0, 26.0, 87.0, 42.0, 19.0, 65.0, 30.0, 51.0, 79.0, 22.0, 47.0, 88.0,
 ];
 
 /// Profit vector B (the other objective). Intentionally anti-correlated with
 /// A on many items so the Pareto front spans a wide trade-off.
 const PROFITS_B: [f64; N_ITEMS] = [
-    24.0, 81.0, 16.0, 67.0, 29.0, 73.0, 41.0, 60.0, 52.0, 19.0,
-    77.0, 34.0, 95.0, 22.0, 71.0, 88.0, 56.0, 27.0, 64.0, 90.0,
-    18.0, 43.0, 79.0, 31.0, 85.0, 25.0, 38.0, 92.0, 70.0, 13.0,
+    24.0, 81.0, 16.0, 67.0, 29.0, 73.0, 41.0, 60.0, 52.0, 19.0, 77.0, 34.0, 95.0, 22.0, 71.0, 88.0,
+    56.0, 27.0, 64.0, 90.0, 18.0, 43.0, 79.0, 31.0, 85.0, 25.0, 38.0, 92.0, 70.0, 13.0,
 ];
 
 /// Item weights.
 const WEIGHTS: [f64; N_ITEMS] = [
-    35.0, 58.0, 22.0, 71.0, 14.0, 86.0, 31.0, 53.0, 78.0, 19.0,
-    44.0, 16.0, 67.0, 88.0, 25.0, 51.0, 33.0, 74.0, 12.0, 47.0,
-    63.0, 28.0, 91.0, 36.0, 55.0, 17.0, 82.0, 41.0, 24.0, 68.0,
+    35.0, 58.0, 22.0, 71.0, 14.0, 86.0, 31.0, 53.0, 78.0, 19.0, 44.0, 16.0, 67.0, 88.0, 25.0, 51.0,
+    33.0, 74.0, 12.0, 47.0, 63.0, 28.0, 91.0, 36.0, 55.0, 17.0, 82.0, 41.0, 24.0, 68.0,
 ];
 
 /// Capacity = roughly half the total weight (standard Zitzler-Thiele convention).
@@ -79,16 +76,16 @@ impl Problem for BiKnapsack {
     }
 
     fn evaluate(&self, take: &Vec<bool>) -> Evaluation {
-        let (pa, pb, w) = take.iter().enumerate().fold(
-            (0.0_f64, 0.0_f64, 0.0_f64),
-            |(pa, pb, w), (i, &t)| {
-                if t {
-                    (pa + PROFITS_A[i], pb + PROFITS_B[i], w + WEIGHTS[i])
-                } else {
-                    (pa, pb, w)
-                }
-            },
-        );
+        let (pa, pb, w) =
+            take.iter()
+                .enumerate()
+                .fold((0.0_f64, 0.0_f64, 0.0_f64), |(pa, pb, w), (i, &t)| {
+                    if t {
+                        (pa + PROFITS_A[i], pb + PROFITS_B[i], w + WEIGHTS[i])
+                    } else {
+                        (pa, pb, w)
+                    }
+                });
         // Penalty: large coefficient on weight overrun, applied to both objectives.
         let overrun = (w - self.cap).max(0.0);
         let penalty = 1000.0 * overrun;
@@ -122,7 +119,10 @@ struct OnePointCrossoverBool;
 
 impl Variation<Vec<bool>> for OnePointCrossoverBool {
     fn vary(&mut self, parents: &[Vec<bool>], rng: &mut Rng) -> Vec<Vec<bool>> {
-        assert!(parents.len() >= 2, "OnePointCrossoverBool requires 2 parents");
+        assert!(
+            parents.len() >= 2,
+            "OnePointCrossoverBool requires 2 parents"
+        );
         let p1 = &parents[0];
         let p2 = &parents[1];
         assert_eq!(p1.len(), p2.len(), "parent lengths differ");
@@ -154,14 +154,19 @@ fn main() {
         RandomBinary { n: N_ITEMS },
         CompositeVariation {
             crossover: OnePointCrossoverBool,
-            mutation: BitFlipMutation { probability: 1.0 / N_ITEMS as f64 },
+            mutation: BitFlipMutation {
+                probability: 1.0 / N_ITEMS as f64,
+            },
         },
     );
     let result = optimizer.run(&problem);
 
     println!("Bi-objective 0/1 knapsack — Zitzler–Thiele style, 30 items");
-    println!("Capacity = {:.0} (≈ half of total weight {:.0})",
-        cap, WEIGHTS.iter().sum::<f64>());
+    println!(
+        "Capacity = {:.0} (≈ half of total weight {:.0})",
+        cap,
+        WEIGHTS.iter().sum::<f64>()
+    );
     println!();
     println!("Total evaluations: {}", result.evaluations);
     println!("Pareto-front size: {}", result.pareto_front.len());
@@ -202,5 +207,8 @@ fn main() {
     let owned: Vec<Candidate<Vec<bool>>> = result.pareto_front.to_vec();
     let hv = hypervolume_2d(&owned, &problem.objectives(), ref_point);
     println!();
-    println!("Hypervolume vs. reference (profit_A=0, profit_B=0): {:.0}", hv);
+    println!(
+        "Hypervolume vs. reference (profit_A=0, profit_B=0): {:.0}",
+        hv
+    );
 }
diff --git a/examples/tsp_operators_compare.rs b/examples/tsp_operators_compare.rs
index 3ecad5e..28b16b2 100644
--- a/examples/tsp_operators_compare.rs
+++ b/examples/tsp_operators_compare.rs
@@ -27,23 +27,59 @@ use std::time::Instant;
 
 /// First 25 cities of TSPLIB KroA100 (EUC_2D).
 const KROA_25: [(f64, f64); 25] = [
-    (1380.0, 939.0), (2848.0, 96.0),  (3510.0, 1671.0), (457.0, 334.0),
-    (3888.0, 666.0), (984.0, 965.0),  (2721.0, 1482.0), (1286.0, 525.0),
-    (2716.0, 1432.0),(738.0, 1325.0), (1251.0, 1832.0), (2728.0, 1698.0),
-    (3815.0, 169.0), (3683.0, 1533.0),(1247.0, 1945.0), (123.0, 862.0),
-    (1234.0, 1946.0),(252.0, 1240.0), (611.0, 673.0),   (2576.0, 1676.0),
-    (928.0, 1700.0), (53.0, 857.0),   (1807.0, 1711.0), (274.0, 1420.0),
+    (1380.0, 939.0),
+    (2848.0, 96.0),
+    (3510.0, 1671.0),
+    (457.0, 334.0),
+    (3888.0, 666.0),
+    (984.0, 965.0),
+    (2721.0, 1482.0),
+    (1286.0, 525.0),
+    (2716.0, 1432.0),
+    (738.0, 1325.0),
+    (1251.0, 1832.0),
+    (2728.0, 1698.0),
+    (3815.0, 169.0),
+    (3683.0, 1533.0),
+    (1247.0, 1945.0),
+    (123.0, 862.0),
+    (1234.0, 1946.0),
+    (252.0, 1240.0),
+    (611.0, 673.0),
+    (2576.0, 1676.0),
+    (928.0, 1700.0),
+    (53.0, 857.0),
+    (1807.0, 1711.0),
+    (274.0, 1420.0),
     (2574.0, 946.0),
 ];
 
 /// First 25 cities of TSPLIB KroB100 (EUC_2D).
 const KROB_25: [(f64, f64); 25] = [
-    (3140.0, 1401.0),(556.0, 1056.0), (3675.0, 1522.0), (1182.0, 1853.0),
-    (3595.0, 1340.0),(1936.0, 953.0), (2722.0, 1311.0), (2839.0, 2055.0),
-    (2253.0, 1242.0),(3142.0, 1591.0),(627.0, 1336.0),  (936.0, 211.0),
-    (4014.0, 471.0), (1376.0, 1452.0),(3289.0, 593.0),  (1453.0, 67.0),
-    (1014.0, 1944.0),(2811.0, 1080.0),(3010.0, 1290.0), (1817.0, 1517.0),
-    (510.0, 458.0),  (1717.0, 1693.0),(1252.0, 1633.0), (1693.0, 1374.0),
+    (3140.0, 1401.0),
+    (556.0, 1056.0),
+    (3675.0, 1522.0),
+    (1182.0, 1853.0),
+    (3595.0, 1340.0),
+    (1936.0, 953.0),
+    (2722.0, 1311.0),
+    (2839.0, 2055.0),
+    (2253.0, 1242.0),
+    (3142.0, 1591.0),
+    (627.0, 1336.0),
+    (936.0, 211.0),
+    (4014.0, 471.0),
+    (1376.0, 1452.0),
+    (3289.0, 593.0),
+    (1453.0, 67.0),
+    (1014.0, 1944.0),
+    (2811.0, 1080.0),
+    (3010.0, 1290.0),
+    (1817.0, 1517.0),
+    (510.0, 458.0),
+    (1717.0, 1693.0),
+    (1252.0, 1633.0),
+    (1693.0, 1374.0),
     (539.0, 1378.0),
 ];
 
@@ -177,7 +213,10 @@ fn main() {
     println!("Bi-objective TSP (KroAB-25): NSGA-II crossover showdown");
     println!("Same population, generations, seed across all runs.");
     println!("Mutation held constant at InversionMutation.");
-    println!("Reference point for hypervolume: ({:.0}, {:.0})", REF_POINT[0], REF_POINT[1]);
+    println!(
+        "Reference point for hypervolume: ({:.0}, {:.0})",
+        REF_POINT[0], REF_POINT[1]
+    );
     println!();
 
     let runs = vec![
@@ -189,13 +228,7 @@ fn main() {
 
     println!(
         "  {:<24} | {:>5} {:>5} | {:>17} | {:>17} | {:>14} | {:>6}",
-        "crossover",
-        "size",
-        "uniq",
-        "A-corner (A, B)",
-        "B-corner (A, B)",
-        "hypervolume",
-        "time"
+        "crossover", "size", "uniq", "A-corner (A, B)", "B-corner (A, B)", "hypervolume", "time"
     );
     println!("  {}", "-".repeat(106));
     for r in &runs {
@@ -223,5 +256,8 @@ fn main() {
                 .unwrap_or(std::cmp::Ordering::Equal)
         })
         .expect("non-empty runs");
-    println!("Best by hypervolume: {} ({:.0})", winner.name, winner.hypervolume);
+    println!(
+        "Best by hypervolume: {} ({:.0})",
+        winner.name, winner.hypervolume
+    );
 }
diff --git a/examples/tsp_ulysses16.rs b/examples/tsp_ulysses16.rs
index ac77bc6..4f7d613 100644
--- a/examples/tsp_ulysses16.rs
+++ b/examples/tsp_ulysses16.rs
@@ -152,7 +152,10 @@ fn main() {
     println!("Source: TSPLIB95 (Groetschel/Padberg)");
     println!();
     println!("Known optimum:    {:>8.0}", KNOWN_OPTIMUM);
-    println!("GA best found:    {:>8.0}   (gap {:+.0}, {:+.2}%)", best_len, gap_abs, gap_pct);
+    println!(
+        "GA best found:    {:>8.0}   (gap {:+.0}, {:+.2}%)",
+        best_len, gap_abs, gap_pct
+    );
     println!();
     println!("Total evaluations: {}", result.evaluations);
     println!("Final population:  {}", result.population.len());
diff --git a/src/algorithms/age_moea.rs b/src/algorithms/age_moea.rs
index dfde1c6..29fbbe6 100644
--- a/src/algorithms/age_moea.rs
+++ b/src/algorithms/age_moea.rs
@@ -599,7 +599,10 @@ mod tests {
         // direction and the loss tie-breaking.
         let translated = vec![vec![1.0, 0.0], vec![0.0, 1.0]];
         let p = estimate_p(&[0, 1], &translated, 2);
-        assert!((p - 0.25).abs() < 1e-12, "expected smallest candidate, got {p}");
+        assert!(
+            (p - 0.25).abs() < 1e-12,
+            "expected smallest candidate, got {p}"
+        );
     }
 
     #[test]
@@ -625,7 +628,11 @@ mod tests {
             mutation: PolynomialMutation::new(bounds, 20.0, 1.0),
         };
         let mut opt = AgeMoea::new(
-            AgeMoeaConfig { population_size: 8, generations: 10, seed: 7 },
+            AgeMoeaConfig {
+                population_size: 8,
+                generations: 10,
+                seed: 7,
+            },
             initializer,
             variation,
         );
@@ -666,7 +673,11 @@ mod tests {
         };
         for pop in [4_usize, 12, 30] {
             let mut opt = AgeMoea::new(
-                AgeMoeaConfig { population_size: pop, generations: 5, seed: 13 },
+                AgeMoeaConfig {
+                    population_size: pop,
+                    generations: 5,
+                    seed: 13,
+                },
                 initializer.clone(),
                 variation.clone(),
             );
@@ -690,7 +701,11 @@ mod tests {
         let pop = 6_usize;
         let gens = 4_usize;
         let mut opt = AgeMoea::new(
-            AgeMoeaConfig { population_size: pop, generations: gens, seed: 13 },
+            AgeMoeaConfig {
+                population_size: pop,
+                generations: gens,
+                seed: 13,
+            },
             initializer,
             variation,
         );
diff --git a/src/algorithms/bayesian_opt.rs b/src/algorithms/bayesian_opt.rs
index 594773c..76f7506 100644
--- a/src/algorithms/bayesian_opt.rs
+++ b/src/algorithms/bayesian_opt.rs
@@ -644,7 +644,10 @@ mod tests {
         // k = exp(-0.5 * (1)^2) = exp(-0.5) ≈ 0.6065
         let got = rbf_kernel(&[0.0], &[1.0], &[1.0], 1.0);
         let expected = (-0.5_f64).exp();
-        assert!((got - expected).abs() < 1e-12, "got {got}, expected {expected}");
+        assert!(
+            (got - expected).abs() < 1e-12,
+            "got {got}, expected {expected}"
+        );
     }
 
     #[test]
diff --git a/src/algorithms/cma_es.rs b/src/algorithms/cma_es.rs
index 0d6de95..317da3a 100644
--- a/src/algorithms/cma_es.rs
+++ b/src/algorithms/cma_es.rs
@@ -766,19 +766,37 @@ mod tests {
         a.constraint_violation = 0.0;
         let mut b = Evaluation::new(vec![1.0]);
         b.constraint_violation = 1.0;
-        assert_eq!(compare_so(&a, &b, Direction::Minimize), std::cmp::Ordering::Less);
-        assert_eq!(compare_so(&b, &a, Direction::Minimize), std::cmp::Ordering::Greater);
+        assert_eq!(
+            compare_so(&a, &b, Direction::Minimize),
+            std::cmp::Ordering::Less
+        );
+        assert_eq!(
+            compare_so(&b, &a, Direction::Minimize),
+            std::cmp::Ordering::Greater
+        );
     }
 
     #[test]
     fn compare_so_two_feasible_under_min_and_max() {
         let a = Evaluation::new(vec![1.0]);
         let b = Evaluation::new(vec![2.0]);
-        assert_eq!(compare_so(&a, &b, Direction::Minimize), std::cmp::Ordering::Less);
-        assert_eq!(compare_so(&b, &a, Direction::Minimize), std::cmp::Ordering::Greater);
+        assert_eq!(
+            compare_so(&a, &b, Direction::Minimize),
+            std::cmp::Ordering::Less
+        );
+        assert_eq!(
+            compare_so(&b, &a, Direction::Minimize),
+            std::cmp::Ordering::Greater
+        );
         // Maximize inverts.
-        assert_eq!(compare_so(&a, &b, Direction::Maximize), std::cmp::Ordering::Greater);
-        assert_eq!(compare_so(&b, &a, Direction::Maximize), std::cmp::Ordering::Less);
+        assert_eq!(
+            compare_so(&a, &b, Direction::Maximize),
+            std::cmp::Ordering::Greater
+        );
+        assert_eq!(
+            compare_so(&b, &a, Direction::Maximize),
+            std::cmp::Ordering::Less
+        );
     }
 
     #[test]
@@ -787,8 +805,14 @@ mod tests {
         a.constraint_violation = 0.5;
         let mut b = Evaluation::new(vec![0.0]);
         b.constraint_violation = 1.0;
-        assert_eq!(compare_so(&a, &b, Direction::Minimize), std::cmp::Ordering::Less);
-        assert_eq!(compare_so(&b, &a, Direction::Minimize), std::cmp::Ordering::Greater);
+        assert_eq!(
+            compare_so(&a, &b, Direction::Minimize),
+            std::cmp::Ordering::Less
+        );
+        assert_eq!(
+            compare_so(&b, &a, Direction::Minimize),
+            std::cmp::Ordering::Greater
+        );
     }
 
     #[test]
diff --git a/src/algorithms/genetic_algorithm.rs b/src/algorithms/genetic_algorithm.rs
index ab6c3e1..2452b18 100644
--- a/src/algorithms/genetic_algorithm.rs
+++ b/src/algorithms/genetic_algorithm.rs
@@ -446,15 +446,24 @@ mod tests {
     fn compare_for_fitness_two_feasible_min_and_max() {
         let lo = fc(1.0);
         let hi = fc(2.0);
-        assert_eq!(compare_for_fitness(&lo, &hi, Direction::Minimize), std::cmp::Ordering::Less);
-        assert_eq!(compare_for_fitness(&lo, &hi, Direction::Maximize), std::cmp::Ordering::Greater);
+        assert_eq!(
+            compare_for_fitness(&lo, &hi, Direction::Minimize),
+            std::cmp::Ordering::Less
+        );
+        assert_eq!(
+            compare_for_fitness(&lo, &hi, Direction::Maximize),
+            std::cmp::Ordering::Greater
+        );
     }
 
     #[test]
     fn compare_for_fitness_two_infeasible_lower_violation_wins() {
         let low = fc_cv(0.0, 0.3);
         let high = fc_cv(0.0, 0.9);
-        assert_eq!(compare_for_fitness(&low, &high, Direction::Minimize), std::cmp::Ordering::Less);
+        assert_eq!(
+            compare_for_fitness(&low, &high, Direction::Minimize),
+            std::cmp::Ordering::Less
+        );
     }
 
     /// `survival_selection` carries `elitism` parents and `n - elitism`
diff --git a/src/algorithms/grea.rs b/src/algorithms/grea.rs
index 1f70883..b497f94 100644
--- a/src/algorithms/grea.rs
+++ b/src/algorithms/grea.rs
@@ -415,7 +415,12 @@ mod tests {
                 mutation: PolynomialMutation::new(bounds, 20.0, 1.0),
             };
             let mut opt = Grea::new(
-                GreaConfig { population_size: pop, generations: 5, grid_divisions: 8, seed: 3 },
+                GreaConfig {
+                    population_size: pop,
+                    generations: 5,
+                    grid_divisions: 8,
+                    seed: 3,
+                },
                 initializer,
                 variation,
             );
diff --git a/src/algorithms/hill_climber.rs b/src/algorithms/hill_climber.rs
index 8973aa2..edfca49 100644
--- a/src/algorithms/hill_climber.rs
+++ b/src/algorithms/hill_climber.rs
@@ -290,7 +290,10 @@ mod tests {
     #[test]
     fn hill_climber_never_worsens_objective() {
         let mut opt = HillClimber::new(
-            HillClimberConfig { iterations: 200, seed: 5 },
+            HillClimberConfig {
+                iterations: 200,
+                seed: 5,
+            },
             RealBounds::new(vec![(-3.0, 3.0); 2]),
             GaussianMutation { sigma: 0.3 },
         );
@@ -306,7 +309,10 @@ mod tests {
     #[test]
     fn hill_climber_decreases_sphere() {
         let mut opt = HillClimber::new(
-            HillClimberConfig { iterations: 500, seed: 11 },
+            HillClimberConfig {
+                iterations: 500,
+                seed: 11,
+            },
             RealBounds::new(vec![(-3.0, 3.0)]),
             GaussianMutation { sigma: 0.2 },
         );
diff --git a/src/algorithms/hype.rs b/src/algorithms/hype.rs
index 66dfa8f..77b4a94 100644
--- a/src/algorithms/hype.rs
+++ b/src/algorithms/hype.rs
@@ -595,6 +595,9 @@ mod tests {
                 wins0 += 1;
             }
         }
-        assert!(wins0 > 130, "index 0 won only {wins0}/200 — comparison likely flipped");
+        assert!(
+            wins0 > 130,
+            "index 0 won only {wins0}/200 — comparison likely flipped"
+        );
     }
 }
diff --git a/src/algorithms/hyperband.rs b/src/algorithms/hyperband.rs
index b300039..f12c0ea 100644
--- a/src/algorithms/hyperband.rs
+++ b/src/algorithms/hyperband.rs
@@ -451,16 +451,31 @@ mod tests {
     fn compare_feasibility_first_and_direction() {
         let feasible = Evaluation::new(vec![10.0]);
         let infeasible = Evaluation::constrained(vec![0.0], 1.0);
-        assert_eq!(compare(&feasible, &infeasible, Direction::Minimize), std::cmp::Ordering::Less);
-        assert_eq!(compare(&infeasible, &feasible, Direction::Minimize), std::cmp::Ordering::Greater);
+        assert_eq!(
+            compare(&feasible, &infeasible, Direction::Minimize),
+            std::cmp::Ordering::Less
+        );
+        assert_eq!(
+            compare(&infeasible, &feasible, Direction::Minimize),
+            std::cmp::Ordering::Greater
+        );
         let lo = Evaluation::new(vec![1.0]);
         let hi = Evaluation::new(vec![2.0]);
-        assert_eq!(compare(&lo, &hi, Direction::Minimize), std::cmp::Ordering::Less);
-        assert_eq!(compare(&lo, &hi, Direction::Maximize), std::cmp::Ordering::Greater);
+        assert_eq!(
+            compare(&lo, &hi, Direction::Minimize),
+            std::cmp::Ordering::Less
+        );
+        assert_eq!(
+            compare(&lo, &hi, Direction::Maximize),
+            std::cmp::Ordering::Greater
+        );
         // two infeasible: smaller violation is "Less" (better).
         let v_lo = Evaluation::constrained(vec![0.0], 0.2);
         let v_hi = Evaluation::constrained(vec![0.0], 0.8);
-        assert_eq!(compare(&v_lo, &v_hi, Direction::Minimize), std::cmp::Ordering::Less);
+        assert_eq!(
+            compare(&v_lo, &v_hi, Direction::Minimize),
+            std::cmp::Ordering::Less
+        );
     }
 
     #[test]
diff --git a/src/algorithms/ibea.rs b/src/algorithms/ibea.rs
index 9c3de2f..d414d71 100644
--- a/src/algorithms/ibea.rs
+++ b/src/algorithms/ibea.rs
@@ -501,7 +501,10 @@ mod tests {
         let pool = vec![ibea_cand(vec![1.0, 1.0]), ibea_cand(vec![2.0, 2.0])];
         let fit = compute_fitness(&pool, &ibea_space(), 0.05);
         assert_eq!(fit.len(), 2);
-        assert!(fit[0] > fit[1], "dominating point should score higher: {fit:?}");
+        assert!(
+            fit[0] > fit[1],
+            "dominating point should score higher: {fit:?}"
+        );
     }
 
     #[test]
diff --git a/src/algorithms/mopso.rs b/src/algorithms/mopso.rs
index 202489a..ce5852e 100644
--- a/src/algorithms/mopso.rs
+++ b/src/algorithms/mopso.rs
@@ -408,8 +408,16 @@ mod tests {
         // Determinism cross-check.
         let mut opt2 = make_optimizer(7);
         let r2 = opt2.run(&SchafferN1);
-        let f1: Vec<Vec<f64>> = r.pareto_front.iter().map(|c| c.evaluation.objectives.clone()).collect();
-        let f2: Vec<Vec<f64>> = r2.pareto_front.iter().map(|c| c.evaluation.objectives.clone()).collect();
+        let f1: Vec<Vec<f64>> = r
+            .pareto_front
+            .iter()
+            .map(|c| c.evaluation.objectives.clone())
+            .collect();
+        let f2: Vec<Vec<f64>> = r2
+            .pareto_front
+            .iter()
+            .map(|c| c.evaluation.objectives.clone())
+            .collect();
         assert_eq!(f1, f2);
     }
 }
diff --git a/src/algorithms/nelder_mead.rs b/src/algorithms/nelder_mead.rs
index 7760a12..178d37f 100644
--- a/src/algorithms/nelder_mead.rs
+++ b/src/algorithms/nelder_mead.rs
@@ -560,14 +560,26 @@ mod tests {
     fn compare_feasibility_first_and_direction() {
         let feasible = Evaluation::new(vec![10.0]);
         let infeasible = Evaluation::constrained(vec![0.0], 1.0);
-        assert_eq!(compare(&feasible, &infeasible, Direction::Minimize), std::cmp::Ordering::Less);
+        assert_eq!(
+            compare(&feasible, &infeasible, Direction::Minimize),
+            std::cmp::Ordering::Less
+        );
         let lo = Evaluation::new(vec![1.0]);
         let hi = Evaluation::new(vec![2.0]);
-        assert_eq!(compare(&lo, &hi, Direction::Minimize), std::cmp::Ordering::Less);
-        assert_eq!(compare(&lo, &hi, Direction::Maximize), std::cmp::Ordering::Greater);
+        assert_eq!(
+            compare(&lo, &hi, Direction::Minimize),
+            std::cmp::Ordering::Less
+        );
+        assert_eq!(
+            compare(&lo, &hi, Direction::Maximize),
+            std::cmp::Ordering::Greater
+        );
         let v_lo = Evaluation::constrained(vec![0.0], 0.2);
         let v_hi = Evaluation::constrained(vec![0.0], 0.8);
-        assert_eq!(compare(&v_lo, &v_hi, Direction::Minimize), std::cmp::Ordering::Less);
+        assert_eq!(
+            compare(&v_lo, &v_hi, Direction::Minimize),
+            std::cmp::Ordering::Less
+        );
     }
 
     #[test]
diff --git a/src/algorithms/paes.rs b/src/algorithms/paes.rs
index 39551a7..12491c0 100644
--- a/src/algorithms/paes.rs
+++ b/src/algorithms/paes.rs
@@ -313,7 +313,11 @@ mod tests {
     fn produces_deterministic_nonempty_front() {
         let make = || {
             Paes::new(
-                PaesConfig { iterations: 40, archive_size: 10, seed: 5 },
+                PaesConfig {
+                    iterations: 40,
+                    archive_size: 10,
+                    seed: 5,
+                },
                 RealBounds::new(vec![(-5.0, 5.0)]),
                 GaussianMutation { sigma: 0.3 },
             )
@@ -321,8 +325,16 @@ mod tests {
         let r1 = make().run(&SchafferN1);
         let r2 = make().run(&SchafferN1);
         assert!(!r1.pareto_front.is_empty());
-        let f1: Vec<Vec<f64>> = r1.pareto_front.iter().map(|c| c.evaluation.objectives.clone()).collect();
-        let f2: Vec<Vec<f64>> = r2.pareto_front.iter().map(|c| c.evaluation.objectives.clone()).collect();
+        let f1: Vec<Vec<f64>> = r1
+            .pareto_front
+            .iter()
+            .map(|c| c.evaluation.objectives.clone())
+            .collect();
+        let f2: Vec<Vec<f64>> = r2
+            .pareto_front
+            .iter()
+            .map(|c| c.evaluation.objectives.clone())
+            .collect();
         assert_eq!(f1, f2);
         // Archive never exceeds its configured cap.
         assert!(r1.pareto_front.len() <= 10);
diff --git a/src/algorithms/pesa2.rs b/src/algorithms/pesa2.rs
index 94110ba..84e8f2f 100644
--- a/src/algorithms/pesa2.rs
+++ b/src/algorithms/pesa2.rs
@@ -560,6 +560,9 @@ mod tests {
         }
         // Index 2 wins whenever it's drawn against 0 or 1, plus half its
         // self-draws — clear majority.
-        assert!(picked_uncrowded > 150, "uncrowded picked {picked_uncrowded}/300");
+        assert!(
+            picked_uncrowded > 150,
+            "uncrowded picked {picked_uncrowded}/300"
+        );
     }
 }
diff --git a/src/algorithms/random_search.rs b/src/algorithms/random_search.rs
index 4b0d2fc..474ee7f 100644
--- a/src/algorithms/random_search.rs
+++ b/src/algorithms/random_search.rs
@@ -224,7 +224,11 @@ mod tests {
     #[test]
     fn best_is_no_worse_than_any_sample() {
         let mut opt = RandomSearch::new(
-            RandomSearchConfig { iterations: 50, batch_size: 2, seed: 9 },
+            RandomSearchConfig {
+                iterations: 50,
+                batch_size: 2,
+                seed: 9,
+            },
             RealBounds::new(vec![(-3.0, 3.0)]),
         );
         let r = opt.run(&Sphere1D);
diff --git a/src/algorithms/rvea.rs b/src/algorithms/rvea.rs
index 87806d1..f17d5cb 100644
--- a/src/algorithms/rvea.rs
+++ b/src/algorithms/rvea.rs
@@ -591,6 +591,9 @@ mod tests {
     fn smallest_neighbor_angle_of_orthogonal_refs_is_pi_over_2() {
         let refs = vec![vec![1.0, 0.0], vec![0.0, 1.0]];
         let a = smallest_neighbor_angle(&refs);
-        assert!((a - std::f64::consts::FRAC_PI_2).abs() < 1e-9, "angle = {a}");
+        assert!(
+            (a - std::f64::consts::FRAC_PI_2).abs() < 1e-9,
+            "angle = {a}"
+        );
     }
 }
diff --git a/src/algorithms/snes.rs b/src/algorithms/snes.rs
index 7182673..4c9fb91 100644
--- a/src/algorithms/snes.rs
+++ b/src/algorithms/snes.rs
@@ -483,11 +483,20 @@ mod tests {
     fn compare_feasibility_first_and_direction() {
         let feasible = Evaluation::new(vec![100.0]);
         let infeasible = Evaluation::constrained(vec![0.0], 1.0);
-        assert_eq!(compare(&feasible, &infeasible, Direction::Minimize), std::cmp::Ordering::Less);
+        assert_eq!(
+            compare(&feasible, &infeasible, Direction::Minimize),
+            std::cmp::Ordering::Less
+        );
         let lo = Evaluation::new(vec![1.0]);
         let hi = Evaluation::new(vec![2.0]);
-        assert_eq!(compare(&lo, &hi, Direction::Minimize), std::cmp::Ordering::Less);
-        assert_eq!(compare(&lo, &hi, Direction::Maximize), std::cmp::Ordering::Greater);
+        assert_eq!(
+            compare(&lo, &hi, Direction::Minimize),
+            std::cmp::Ordering::Less
+        );
+        assert_eq!(
+            compare(&lo, &hi, Direction::Maximize),
+            std::cmp::Ordering::Greater
+        );
     }
 
     #[test]
diff --git a/src/algorithms/umda.rs b/src/algorithms/umda.rs
index 520da3e..b88a519 100644
--- a/src/algorithms/umda.rs
+++ b/src/algorithms/umda.rs
@@ -456,14 +456,26 @@ mod tests {
     fn compare_so_feasibility_first_and_direction() {
         let feasible = Evaluation::new(vec![100.0]);
         let infeasible = Evaluation::constrained(vec![0.0], 1.0);
-        assert_eq!(compare_so(&feasible, &infeasible, Direction::Minimize), std::cmp::Ordering::Less);
+        assert_eq!(
+            compare_so(&feasible, &infeasible, Direction::Minimize),
+            std::cmp::Ordering::Less
+        );
         let lo = Evaluation::new(vec![1.0]);
         let hi = Evaluation::new(vec![2.0]);
-        assert_eq!(compare_so(&lo, &hi, Direction::Minimize), std::cmp::Ordering::Less);
-        assert_eq!(compare_so(&lo, &hi, Direction::Maximize), std::cmp::Ordering::Greater);
+        assert_eq!(
+            compare_so(&lo, &hi, Direction::Minimize),
+            std::cmp::Ordering::Less
+        );
+        assert_eq!(
+            compare_so(&lo, &hi, Direction::Maximize),
+            std::cmp::Ordering::Greater
+        );
         let v_lo = Evaluation::constrained(vec![0.0], 0.2);
         let v_hi = Evaluation::constrained(vec![0.0], 0.8);
-        assert_eq!(compare_so(&v_lo, &v_hi, Direction::Minimize), std::cmp::Ordering::Less);
+        assert_eq!(
+            compare_so(&v_lo, &v_hi, Direction::Minimize),
+            std::cmp::Ordering::Less
+        );
     }
 
     #[test]
diff --git a/src/explorer/mod.rs b/src/explorer/mod.rs
index 0a9f64f..0a308c7 100644
--- a/src/explorer/mod.rs
+++ b/src/explorer/mod.rs
@@ -598,9 +598,18 @@ mod tests {
         let v: Vec<i64> = vec![-3, 0, 7];
         let got = v.to_decision_values();
         assert_eq!(got.len(), 3);
-        assert_eq!(got[0], serde_json::Value::Number(serde_json::Number::from(-3i64)));
-        assert_eq!(got[1], serde_json::Value::Number(serde_json::Number::from(0i64)));
-        assert_eq!(got[2], serde_json::Value::Number(serde_json::Number::from(7i64)));
+        assert_eq!(
+            got[0],
+            serde_json::Value::Number(serde_json::Number::from(-3i64))
+        );
+        assert_eq!(
+            got[1],
+            serde_json::Value::Number(serde_json::Number::from(0i64))
+        );
+        assert_eq!(
+            got[2],
+            serde_json::Value::Number(serde_json::Number::from(7i64))
+        );
     }
 
     /// Pins the *exact* booleans, not just the count.
@@ -642,8 +651,7 @@ mod tests {
     fn from_result_propagates_evaluation_and_generation_counts() {
         let problem = SingleObjMin;
         let cands = vec![Candidate::new(vec![1.0], Evaluation::new(vec![1.0]))];
-        let result =
-            OptimizationResult::new(Population::new(cands.clone()), cands, None, 137, 9);
+        let result = OptimizationResult::new(Population::new(cands.clone()), cands, None, 137, 9);
         let export = ExplorerExport::from_result(&problem, &result);
         assert_eq!(export.run.evaluations, 137);
         assert_eq!(export.run.generations, 9);
@@ -654,8 +662,8 @@ mod tests {
     fn with_problem_name_sets_field_and_preserves_other_state() {
         let problem = SingleObjMin;
         let result = make_result(vec![vec![1.0]], |d| vec![d[0]]);
-        let export = ExplorerExport::from_result(&problem, &result)
-            .with_problem_name("Toy Problem");
+        let export =
+            ExplorerExport::from_result(&problem, &result).with_problem_name("Toy Problem");
         assert_eq!(export.run.problem_name.as_deref(), Some("Toy Problem"));
         // The candidates and objectives should still be intact, proving the
         // chained builder isn't replacing the whole struct.
@@ -678,9 +686,12 @@ mod tests {
     fn with_timestamp_sets_field_and_preserves_other_state() {
         let problem = SingleObjMin;
         let result = make_result(vec![vec![1.0]], |d| vec![d[0]]);
-        let export = ExplorerExport::from_result(&problem, &result)
-            .with_timestamp("2025-01-01T00:00:00Z");
-        assert_eq!(export.run.timestamp.as_deref(), Some("2025-01-01T00:00:00Z"));
+        let export =
+            ExplorerExport::from_result(&problem, &result).with_timestamp("2025-01-01T00:00:00Z");
+        assert_eq!(
+            export.run.timestamp.as_deref(),
+            Some("2025-01-01T00:00:00Z")
+        );
         assert_eq!(export.candidates.len(), 1);
     }
 
@@ -708,8 +719,7 @@ mod tests {
     fn to_writer_emits_full_export() {
         let problem = SingleObjMin;
         let result = make_result(vec![vec![1.0]], |d| vec![d[0]]);
-        let export = ExplorerExport::from_result(&problem, &result)
-            .with_problem_name("MyProblem");
+        let export = ExplorerExport::from_result(&problem, &result).with_problem_name("MyProblem");
         let mut buf: Vec<u8> = Vec::new();
         export.to_writer(&mut buf).unwrap();
         assert!(!buf.is_empty());
@@ -725,16 +735,15 @@ mod tests {
         use std::io::Read;
         let problem = SingleObjMin;
         let result = make_result(vec![vec![1.0]], |d| vec![d[0]]);
-        let export = ExplorerExport::from_result(&problem, &result)
-            .with_problem_name("OnDisk");
+        let export = ExplorerExport::from_result(&problem, &result).with_problem_name("OnDisk");
         let dir = std::env::temp_dir();
-        let path = dir.join(format!(
-            "heuropt-explorer-test-{}.json",
-            std::process::id()
-        ));
+        let path = dir.join(format!("heuropt-explorer-test-{}.json", std::process::id()));
         export.to_file(&path).unwrap();
         let mut s = String::new();
-        std::fs::File::open(&path).unwrap().read_to_string(&mut s).unwrap();
+        std::fs::File::open(&path)
+            .unwrap()
+            .read_to_string(&mut s)
+            .unwrap();
         let _ = std::fs::remove_file(&path);
         let back: ExplorerExport = serde_json::from_str(&s).unwrap();
         assert_eq!(back.run.problem_name.as_deref(), Some("OnDisk"));
@@ -777,7 +786,10 @@ mod tests {
         ));
         super::to_file(&path, &problem, &DummyAlgo, &result).unwrap();
         let mut s = String::new();
-        std::fs::File::open(&path).unwrap().read_to_string(&mut s).unwrap();
+        std::fs::File::open(&path)
+            .unwrap()
+            .read_to_string(&mut s)
+            .unwrap();
         let _ = std::fs::remove_file(&path);
         let back: ExplorerExport = serde_json::from_str(&s).unwrap();
         assert_eq!(back.run.algorithm.as_deref(), Some("DummyAlgo"));
@@ -877,8 +889,7 @@ mod tests {
     /// the pad (too few objectives) and truncate (too many) cases.
     #[test]
     fn candidate_to_export_pads_short_objectives_with_nan() {
-        let c: Candidate<Vec<f64>> =
-            Candidate::new(vec![1.0], Evaluation::new(vec![1.0]));
+        let c: Candidate<Vec<f64>> = Candidate::new(vec![1.0], Evaluation::new(vec![1.0]));
         let exported = candidate_to_export(&c, 0, 3);
         assert_eq!(exported.objectives.len(), 3);
         assert_eq!(exported.objectives[0], 1.0);
diff --git a/src/metrics/hypervolume.rs b/src/metrics/hypervolume.rs
index 008eafa..d09071f 100644
--- a/src/metrics/hypervolume.rs
+++ b/src/metrics/hypervolume.rs
@@ -560,12 +560,12 @@ mod nd_tests {
     /// positive value for a dominating point.
     #[test]
     fn hypervolume_nd_from_evaluations_empty_and_nonempty() {
-        let s = ObjectiveSpace::new(vec![
-            Objective::minimize("f1"),
-            Objective::minimize("f2"),
-        ]);
+        let s = ObjectiveSpace::new(vec![Objective::minimize("f1"), Objective::minimize("f2")]);
         let empty: Vec<&Evaluation> = Vec::new();
-        assert_eq!(hypervolume_nd_from_evaluations(&empty, &s, &[2.0, 2.0]), 0.0);
+        assert_eq!(
+            hypervolume_nd_from_evaluations(&empty, &s, &[2.0, 2.0]),
+            0.0
+        );
 
         let e = Evaluation::new(vec![1.0, 1.0]);
         let evals = vec![&e];
@@ -577,13 +577,13 @@ mod nd_tests {
     /// A point that does not strictly dominate the reference contributes 0.
     #[test]
     fn hypervolume_nd_from_evaluations_skips_non_dominating() {
-        let s = ObjectiveSpace::new(vec![
-            Objective::minimize("f1"),
-            Objective::minimize("f2"),
-        ]);
+        let s = ObjectiveSpace::new(vec![Objective::minimize("f1"), Objective::minimize("f2")]);
         // (2, 1): axis 0 equals the reference → not strictly dominating.
         let e = Evaluation::new(vec![2.0, 1.0]);
         let evals = vec![&e];
-        assert_eq!(hypervolume_nd_from_evaluations(&evals, &s, &[2.0, 2.0]), 0.0);
+        assert_eq!(
+            hypervolume_nd_from_evaluations(&evals, &s, &[2.0, 2.0]),
+            0.0
+        );
     }
 }
diff --git a/src/metrics/spacing.rs b/src/metrics/spacing.rs
index 9b5862a..538086b 100644
--- a/src/metrics/spacing.rs
+++ b/src/metrics/spacing.rs
@@ -135,7 +135,10 @@ mod tests {
         ];
         let got = spacing(&front, &s);
         let expected = (1536.0_f64 / 27.0).sqrt();
-        assert!((got - expected).abs() < 1e-9, "got {got}, expected {expected}");
+        assert!(
+            (got - expected).abs() < 1e-9,
+            "got {got}, expected {expected}"
+        );
     }
 
     /// A perfectly even front has zero spacing — the variance term is 0.
diff --git a/src/operators/permutation.rs b/src/operators/permutation.rs
index 97fb9b9..1353197 100644
--- a/src/operators/permutation.rs
+++ b/src/operators/permutation.rs
@@ -994,7 +994,10 @@ mod tests {
             let c = m.vary(std::slice::from_ref(&parent), &mut rng);
             c[0] != parent
         });
-        assert!(any_changed, "InversionMutation never modified an 8-element parent across 30 seeds");
+        assert!(
+            any_changed,
+            "InversionMutation never modified an 8-element parent across 30 seeds"
+        );
     }
 
     /// `InsertionMutation` shifts an element across many seeds; at least one
@@ -1195,6 +1198,9 @@ mod tests {
             let kids = erx.vary(&[p1.clone(), p2.clone()], &mut rng);
             kids[0] != kids[1]
         });
-        assert!(any_distinct, "ERX never produced distinct children across 30 seeds");
+        assert!(
+            any_distinct,
+            "ERX never produced distinct children across 30 seeds"
+        );
     }
 }
diff --git a/src/operators/real.rs b/src/operators/real.rs
index 62fac68..f070d9c 100644
--- a/src/operators/real.rs
+++ b/src/operators/real.rs
@@ -733,7 +733,11 @@ mod tests {
     // snapshot, by design.
 
     fn assert_close_slice(got: &[f64], want: &[f64], tol: f64) {
-        assert_eq!(got.len(), want.len(), "length mismatch: got {got:?} want {want:?}");
+        assert_eq!(
+            got.len(),
+            want.len(),
+            "length mismatch: got {got:?} want {want:?}"
+        );
         for (g, w) in got.iter().zip(want.iter()) {
             assert!((g - w).abs() < tol, "got {g}, want {w}; full got = {got:?}");
         }
@@ -747,7 +751,11 @@ mod tests {
         let children = m.vary(std::slice::from_ref(&parent), &mut rng);
         assert_close_slice(
             &children[0],
-            &[1.034_713_959_180_981_7, 2.066_469_060_997_062_6, 3.131_288_178_686_977],
+            &[
+                1.034_713_959_180_981_7,
+                2.066_469_060_997_062_6,
+                3.131_288_178_686_977,
+            ],
             1e-12,
         );
     }
@@ -854,7 +862,10 @@ mod tests {
         // Same seed → same δ; the only difference is the (hi-lo) factor.
         // Ratio must be ≈ 10.
         let ratio = wide / narrow;
-        assert!((ratio - 10.0).abs() < 1e-12, "ratio = {ratio}, narrow={narrow}, wide={wide}");
+        assert!(
+            (ratio - 10.0).abs() < 1e-12,
+            "ratio = {ratio}, narrow={narrow}, wide={wide}"
+        );
     }
 
     #[test]
@@ -890,10 +901,7 @@ mod tests {
     fn mantegna_sigma_u_alpha_1_0_pinned() {
         // alpha = 1.0: sin(π/2) = 1, gamma(2) = 1, gamma(1) = 1 → σᵤ ≈ 1.
         let got = mantegna_sigma_u(1.0);
-        assert!(
-            (got - 1.0).abs() < 1e-12,
-            "mantegna_sigma_u(1.0) = {got}",
-        );
+        assert!((got - 1.0).abs() < 1e-12, "mantegna_sigma_u(1.0) = {got}",);
     }
 
     #[test]
diff --git a/src/pareto/archive.rs b/src/pareto/archive.rs
index c8c6fc6..2ccb6da 100644
--- a/src/pareto/archive.rs
+++ b/src/pareto/archive.rs
@@ -317,9 +317,15 @@ mod tests {
     #[test]
     fn infeasible_candidate_with_smaller_violation_evicts_larger() {
         let mut a = ParetoArchive::<u32>::new(space_min2());
-        a.insert(Candidate::new(1u32, Evaluation::constrained(vec![0.0, 0.0], 1.0)));
+        a.insert(Candidate::new(
+            1u32,
+            Evaluation::constrained(vec![0.0, 0.0], 1.0),
+        ));
         // Smaller violation → dominates the existing infeasible member.
-        a.insert(Candidate::new(2u32, Evaluation::constrained(vec![9.0, 9.0], 0.5)));
+        a.insert(Candidate::new(
+            2u32,
+            Evaluation::constrained(vec![9.0, 9.0], 0.5),
+        ));
         assert_eq!(a.members().len(), 1);
         assert_eq!(a.members()[0].decision, 2);
     }
diff --git a/src/pareto/crowding.rs b/src/pareto/crowding.rs
index aa06bce..aee2e07 100644
--- a/src/pareto/crowding.rs
+++ b/src/pareto/crowding.rs
@@ -169,7 +169,11 @@ mod tests {
     fn interior_point_distance_is_pinned() {
         let s = space_min2();
         // Front along the line f1 + f2 = 4: (0,4), (2,2), (4,0).
-        let pop = [cand(vec![0.0, 4.0]), cand(vec![2.0, 2.0]), cand(vec![4.0, 0.0])];
+        let pop = [
+            cand(vec![0.0, 4.0]),
+            cand(vec![2.0, 2.0]),
+            cand(vec![4.0, 0.0]),
+        ];
         let d = crowding_distance(&pop, &[0, 1, 2], &s);
         // Boundary points are infinite; the middle point gets
         // (4-0)/4 + (4-0)/4 = 2.0 (objective 0 span 4, objective 1 span 4).
@@ -184,7 +188,11 @@ mod tests {
     fn asymmetric_interior_distance_is_pinned() {
         let s = space_min2();
         // (0,10), (1,2), (10,0): objective-0 span = 10, objective-1 span = 10.
-        let pop = [cand(vec![0.0, 10.0]), cand(vec![1.0, 2.0]), cand(vec![10.0, 0.0])];
+        let pop = [
+            cand(vec![0.0, 10.0]),
+            cand(vec![1.0, 2.0]),
+            cand(vec![10.0, 0.0]),
+        ];
         let d = crowding_distance(&pop, &[0, 1, 2], &s);
         // middle point: obj0 (10-0)/10 = 1.0; obj1 (10-0)/10 = 1.0 → 2.0.
         assert!((d[1] - 2.0).abs() < 1e-12, "got {}", d[1]);
diff --git a/src/selection/tournament.rs b/src/selection/tournament.rs
index ab9ef9c..764ec39 100644
--- a/src/selection/tournament.rs
+++ b/src/selection/tournament.rs
@@ -282,15 +282,27 @@ mod tests {
         let feasible = cand_min(1, 100.0);
         let infeasible = constrained(2, 0.0, 1.0);
         assert!(challenger_wins(&feasible, &infeasible, Direction::Minimize));
-        assert!(!challenger_wins(&infeasible, &feasible, Direction::Minimize));
+        assert!(!challenger_wins(
+            &infeasible,
+            &feasible,
+            Direction::Minimize
+        ));
     }
 
     #[test]
     fn challenger_wins_two_infeasible_compares_violation() {
         let less_violating = constrained(1, 0.0, 0.5);
         let more_violating = constrained(2, 0.0, 1.0);
-        assert!(challenger_wins(&less_violating, &more_violating, Direction::Minimize));
-        assert!(!challenger_wins(&more_violating, &less_violating, Direction::Minimize));
+        assert!(challenger_wins(
+            &less_violating,
+            &more_violating,
+            Direction::Minimize
+        ));
+        assert!(!challenger_wins(
+            &more_violating,
+            &less_violating,
+            Direction::Minimize
+        ));
     }
 
     #[test]
@@ -330,17 +342,37 @@ mod tests {
         let feasible_a = Evaluation::new(vec![10.0]);
         let infeasible_b = Evaluation::constrained(vec![0.0], 1.0);
         // feasible vs infeasible
-        assert!(better_by_feasibility(&feasible_a, &infeasible_b, Direction::Minimize));
-        assert!(!better_by_feasibility(&infeasible_b, &feasible_a, Direction::Minimize));
+        assert!(better_by_feasibility(
+            &feasible_a,
+            &infeasible_b,
+            Direction::Minimize
+        ));
+        assert!(!better_by_feasibility(
+            &infeasible_b,
+            &feasible_a,
+            Direction::Minimize
+        ));
         // two infeasible: smaller violation wins
         let low_cv = Evaluation::constrained(vec![0.0], 0.3);
         let high_cv = Evaluation::constrained(vec![0.0], 0.9);
-        assert!(better_by_feasibility(&low_cv, &high_cv, Direction::Minimize));
-        assert!(!better_by_feasibility(&high_cv, &low_cv, Direction::Minimize));
+        assert!(better_by_feasibility(
+            &low_cv,
+            &high_cv,
+            Direction::Minimize
+        ));
+        assert!(!better_by_feasibility(
+            &high_cv,
+            &low_cv,
+            Direction::Minimize
+        ));
         // two feasible: delegates to better_by_objective
         let feasible_lower = Evaluation::new(vec![1.0]);
         let feasible_higher = Evaluation::new(vec![2.0]);
-        assert!(better_by_feasibility(&feasible_lower, &feasible_higher, Direction::Minimize));
+        assert!(better_by_feasibility(
+            &feasible_lower,
+            &feasible_higher,
+            Direction::Minimize
+        ));
     }
 
     #[test]
@@ -349,8 +381,8 @@ mod tests {
         // must rank first regardless of objective value.
         let s = ObjectiveSpace::new(vec![Objective::minimize("f")]);
         let pop = [
-            constrained(1, 0.0, 2.0),  // infeasible, great objective
-            cand_min(2, 100.0),         // feasible, terrible objective
+            constrained(1, 0.0, 2.0), // infeasible, great objective
+            cand_min(2, 100.0),       // feasible, terrible objective
         ];
         let mut rng = rng_from_seed(7);
         let picks = stochastic_ranking_select(&pop, &s, 0.0, 1, &mut rng);