fix: always throw DivideByZeroException when BloomFilter is empty (

#3502)

* fix: always throw divided by zero when BloomFilter is empty

* fix: always throw divided by zero when BloomFilter is empty

src/Neo/Cryptography/BloomFilter.cs

@@ -41,12 +41,13 @@ public class BloomFilter
         /// <summary>
         /// Initializes a new instance of the <see cref="BloomFilter"/> class.
         /// </summary>
-        /// <param name="m">The size of the bit array used by the bloom filter.</param>
-        /// <param name="k">The number of hash functions used by the bloom filter.</param>
+        /// <param name="m">The size of the bit array used by the bloom filter, and must be greater than 0.</param>
+        /// <param name="k">The number of hash functions used by the bloom filter, and must be greater than 0.</param>
         /// <param name="nTweak">Used to generate the seeds of the murmur hash functions.</param>
+        /// <exception cref="ArgumentOutOfRangeException">Thrown when <paramref name="k"/> or <paramref name="m"/> is less than or equal to 0.</exception>
         public BloomFilter(int m, int k, uint nTweak)
         {
-            if (k < 0 || m < 0) throw new ArgumentOutOfRangeException();
+            if (k <= 0 || m <= 0) throw new ArgumentOutOfRangeException();
             seeds = Enumerable.Range(0, k).Select(p => (uint)p * 0xFBA4C795 + nTweak).ToArray();
             bits = new BitArray(m)
             {
@@ -58,13 +59,14 @@ public BloomFilter(int m, int k, uint nTweak)
         /// <summary>
         /// Initializes a new instance of the <see cref="BloomFilter"/> class.
         /// </summary>
-        /// <param name="m">The size of the bit array used by the bloom filter.</param>
-        /// <param name="k">The number of hash functions used by the bloom filter.</param>
+        /// <param name="m">The size of the bit array used by the bloom filter, and must be greater than 0.</param>
+        /// <param name="k">The number of hash functions used by the bloom filter, and must be greater than 0.</param>
         /// <param name="nTweak">Used to generate the seeds of the murmur hash functions.</param>
         /// <param name="elements">The initial elements contained in this <see cref="BloomFilter"/> object.</param>
+        /// <exception cref="ArgumentOutOfRangeException">Thrown when <paramref name="k"/> or <paramref name="m"/> is less than or equal to 0.</exception>
         public BloomFilter(int m, int k, uint nTweak, ReadOnlyMemory<byte> elements)
         {
-            if (k < 0 || m < 0) throw new ArgumentOutOfRangeException();
+            if (k <= 0 || m <= 0) throw new ArgumentOutOfRangeException();
             seeds = Enumerable.Range(0, k).Select(p => (uint)p * 0xFBA4C795 + nTweak).ToArray();
             bits = new BitArray(elements.ToArray())
             {

tests/Neo.UnitTests/Cryptography/UT_BloomFilter.cs

@@ -78,5 +78,16 @@ public void TestGetBits()
             foreach (byte value in result)
                 value.Should().Be(0);
         }
+
+        [TestMethod]
+        public void TestInvalidArguments()
+        {
+            uint nTweak = 123456;
+            Action action = () => new BloomFilter(0, 3, nTweak);
+            action.Should().Throw<ArgumentOutOfRangeException>();
+
+            action = () => new BloomFilter(3, 0, nTweak);
+            action.Should().Throw<ArgumentOutOfRangeException>();
+        }
     }
 }