commit 01ba89bf26da87e998cbc68262afc637ea4dd615
author rednikeeg <maks.schoolforvv@gmail.com> Fri Aug 19 21:27:11 2022 +0300
committer Gilles Sadowski <gilleseran@gmail.com> Sat Aug 20 02:34:44 2022 +0200
tree c79cdcdc32357d81e9e2329be37451b651b1cc0e
parent 3c1c92d3eb6c13db92ea6123f8ad0d2383117f66

MATH-1647: Enforce precondition (index must be larger than 0).

commons-math-legacy/src/main/java/org/apache/commons/math4/legacy/random/HaltonSequenceGenerator.java

diff --git a/commons-math-legacy/src/main/java/org/apache/commons/math4/legacy/random/HaltonSequenceGenerator.java b/commons-math-legacy/src/main/java/org/apache/commons/math4/legacy/random/HaltonSequenceGenerator.java
index 8a17561..3805be4 100644
--- a/commons-math-legacy/src/main/java/org/apache/commons/math4/legacy/random/HaltonSequenceGenerator.java
+++ b/commons-math-legacy/src/main/java/org/apache/commons/math4/legacy/random/HaltonSequenceGenerator.java
@@ -19,6 +19,7 @@
 import java.util.function.Supplier;
 
 import org.apache.commons.math4.legacy.exception.DimensionMismatchException;
+import org.apache.commons.math4.legacy.exception.NotPositiveException;
 import org.apache.commons.math4.legacy.exception.NullArgumentException;
 import org.apache.commons.math4.legacy.exception.OutOfRangeException;
 
@@ -165,6 +166,10 @@
      * @throws org.apache.commons.math4.legacy.exception.NotPositiveException NotPositiveException if index < 0
      */
     public double[] skipTo(final int index) {
+        if (index < 0) {
+            throw new NotPositiveException(index);
+        }
+
         count = index;
         return get();
     }

commons-math-legacy/src/test/java/org/apache/commons/math4/legacy/random/HaltonSequenceGeneratorTest.java

diff --git a/commons-math-legacy/src/test/java/org/apache/commons/math4/legacy/random/HaltonSequenceGeneratorTest.java b/commons-math-legacy/src/test/java/org/apache/commons/math4/legacy/random/HaltonSequenceGeneratorTest.java
index 4dd800b..c1931f5 100644
--- a/commons-math-legacy/src/test/java/org/apache/commons/math4/legacy/random/HaltonSequenceGeneratorTest.java
+++ b/commons-math-legacy/src/test/java/org/apache/commons/math4/legacy/random/HaltonSequenceGeneratorTest.java
@@ -18,6 +18,7 @@
 
 import org.junit.Assert;
 import org.apache.commons.math4.legacy.exception.DimensionMismatchException;
+import org.apache.commons.math4.legacy.exception.NotPositiveException;
 import org.apache.commons.math4.legacy.exception.NullArgumentException;
 import org.apache.commons.math4.legacy.exception.OutOfRangeException;
 import org.junit.Before;
@@ -131,4 +132,13 @@
         }
     }
 
+    @Test
+    public void testSkipToNegative() {
+        try {
+            generator.skipTo(-4584);
+            Assert.fail("an exception should have been thrown");
+        } catch (NotPositiveException e) {
+            // expected
+        }
+    }
 }