[lucenenet] 08/27: Lucene.Net.TestFramework:RandomExtensions: Added missing overload of NextInt64(long) to choose only max upper bound

[ni...@apache.org]

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nightowl888 pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/lucenenet.git

commit b66279b4112377bc83352e4e883c53e8617d9749
Author: Shad Storhaug <sh...@shadstorhaug.com>
AuthorDate: Sun Jun 28 17:47:52 2020 +0700

    Lucene.Net.TestFramework:RandomExtensions: Added missing overload of NextInt64(long) to choose only max upper bound
---
 .../Support/RandomExtensions.cs                    | 31 ++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/src/Lucene.Net.TestFramework/Support/RandomExtensions.cs b/src/Lucene.Net.TestFramework/Support/RandomExtensions.cs
index 2de8fa8..9fdc366 100644
--- a/src/Lucene.Net.TestFramework/Support/RandomExtensions.cs
+++ b/src/Lucene.Net.TestFramework/Support/RandomExtensions.cs
@@ -4,6 +4,7 @@ using Lucene.Net.Util;
 using System;
 using System.Collections.Generic;
 using System.Text.RegularExpressions;
+using J2N.Numerics;
 
 namespace Lucene.Net
 {
@@ -71,6 +72,36 @@ namespace Lucene.Net
         }
 
         /// <summary>
+        /// Generates a random <see cref="long"/> between <c>0</c> (inclusive)
+        /// and <paramref name="n"/> (exclusive).
+        /// </summary>
+        /// <param name="random">This <see cref="Random"/>.</param>
+        /// <param name="n">The bound on the random number to be returned. Must be positive.</param>
+        /// <returns>A random <see cref="long"/> between 0 and <paramref name="n"/>-1.</returns>
+        public static long NextInt64(this Random random, long n)
+        {
+            if (n <= 0)
+            {
+                throw new ArgumentOutOfRangeException(nameof(n), $"{n} <= 0: " + n);
+            }
+
+            long value = NextInt64(random);
+            long range = n - 1;
+            if ((n & range) == 0L)
+            {
+                value &= range;
+            }
+            else
+            {
+                for (long u = value.TripleShift(1); u + range - (value = u % n) < 0L;)
+                {
+                    u = NextInt64(random).TripleShift(1);
+                }
+            }
+            return value;
+        }
+
+        /// <summary>
         /// Generates a random <see cref="float"/>.
         /// </summary>
         /// <param name="random">This <see cref="Random"/>.</param>