(commons-rng) branch master updated: Avoid rejection bound that invalidates the test in ArraySamplerTest

[ah...@apache.org]

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aherbert pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/commons-rng.git


The following commit(s) were added to refs/heads/master by this push:
     new 8253623d Avoid rejection bound that invalidates the test in ArraySamplerTest
8253623d is described below

commit 8253623d49466db0d219cadd3e887d315d6d2631
Author: Alex Herbert <ah...@apache.org>
AuthorDate: Tue Feb 17 08:35:57 2026 +0000

    Avoid rejection bound that invalidates the test in ArraySamplerTest
---
 .../commons/rng/sampling/ArraySamplerTest.java     | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/commons-rng-sampling/src/test/java/org/apache/commons/rng/sampling/ArraySamplerTest.java b/commons-rng-sampling/src/test/java/org/apache/commons/rng/sampling/ArraySamplerTest.java
index 26c607c4..ea469bc2 100644
--- a/commons-rng-sampling/src/test/java/org/apache/commons/rng/sampling/ArraySamplerTest.java
+++ b/commons-rng-sampling/src/test/java/org/apache/commons/rng/sampling/ArraySamplerTest.java
@@ -577,14 +577,24 @@ class ArraySamplerTest {
         };
 
         for (int i = 0; i < 100; i++) {
-            // Avoid an index bound of 0 or 1 by adding 2
-            final int n = 2 + rng.nextInt(ABOVE_BATCH_LIMIT);
-            final int[] bound1 = {n * (n - 1)};
+            // Create the bound.
+            // The random output of zero will only be rejected if
+            // unused bits < (2^32 % bound).
+            // Ensure this threshold is above zero
+            int n = 0;
+            int bound = 1;
+            while ((1L << 32) % bound == 0) {
+                // Avoid an index bound of 0 or 1
+                n = rng.nextInt(2, ABOVE_BATCH_LIMIT);
+                bound = n * (n - 1);
+            }
+            final int[] bound1 = {bound};
             final int[] i1 = ArraySampler.randomBounded2(n, n - 1, bound1, rng1);
-            final int[] bound2 = {n * (n - 1)};
+            final int[] bound2 = {bound};
             final int[] i2 = ArraySampler.randomBounded2(n, n - 1, bound2, rng2);
-            Assertions.assertArrayEquals(i1, i2, "indices");
-            Assertions.assertArrayEquals(bound1, bound2, "bounds");
+            final int nn = n;
+            Assertions.assertArrayEquals(i1, i2, () -> "indices: n=" + nn);
+            Assertions.assertArrayEquals(bound1, bound2, () -> "bounds: n=" + nn);
         }
     }