Support for BF.CARD

src/NRedisStack/Bloom/BloomCommandBuilder.cs

@@ -11,6 +11,11 @@ public static SerializedCommand Add(RedisKey key, RedisValue item)
             return new SerializedCommand(BF.ADD, key, item);
         }
 
+        public static SerializedCommand Card(RedisKey key)
+        {
+            return new SerializedCommand(BF.CARD, key);
+        }
+
         public static SerializedCommand Exists(RedisKey key, RedisValue item)
         {
             return new SerializedCommand(BF.EXISTS, key, item);

src/NRedisStack/Bloom/BloomCommands.cs

@@ -23,6 +23,18 @@ public async Task<bool> AddAsync(RedisKey key, RedisValue item)
             return (await _db.ExecuteAsync(BloomCommandBuilder.Add(key, item))).ToString() == "1";
         }
 
+        /// <inheritdoc/>
+        public long Card(RedisKey key)
+        {
+            return _db.Execute(BloomCommandBuilder.Card(key)).ToLong();
+        }
+
+        /// <inheritdoc/>
+        public async Task<long> CardAsync(RedisKey key)
+        {
+            return (await _db.ExecuteAsync(BloomCommandBuilder.Card(key))).ToLong();
+        }
+
         /// <inheritdoc/>
         public bool Exists(RedisKey key, RedisValue item)
         {

src/NRedisStack/Bloom/IBloomCommands.cs

@@ -23,6 +23,22 @@ public interface IBloomCommands
         /// <remarks><seealso href="https://redis.io/commands/bf.add"/></remarks>
         Task<bool> AddAsync(RedisKey key, RedisValue item);
 
+        /// <summary>
+        /// Returns the cardinality of a Bloom filter.
+        /// </summary>
+        /// <param name="key">The name of the filter.</param>
+        /// <returns>number of items that were added to a Bloom filter and detected as unique.</returns>
+        /// <remarks><seealso href="https://redis.io/commands/bf.card"/></remarks>
+        long Card(RedisKey key);
+
+        /// <summary>
+        /// Returns the cardinality of a Bloom filter.
+        /// </summary>
+        /// <param name="key">The name of the filter.</param>
+        /// <returns>number of items that were added to a Bloom filter and detected as unique.</returns>
+        /// <remarks><seealso href="https://redis.io/commands/bf.card"/></remarks>
+        Task<long> CardAsync(RedisKey key);
+
         /// <summary>
         /// Checks whether an item exist in the Bloom Filter or not.
         /// </summary>

src/NRedisStack/Bloom/Literals/Commands.cs

@@ -3,6 +3,7 @@
     internal class BF
     {
         public const string ADD = "BF.ADD";
+        public const string CARD = "BF.CARD";
         public const string EXISTS = "BF.EXISTS";
         public const string INFO = "BF.INFO";
         public const string INSERT = "BF.INSERT";

tests/NRedisStack.Tests/Bloom/BloomTests.cs

@@ -331,6 +331,44 @@ public void TestModulePrefixs()
         Assert.NotEqual(bf1.GetHashCode(), bf2.GetHashCode());
     }
 
+    [Fact]
+    public void TestCard()
+    {
+        IDatabase db = redisFixture.Redis.GetDatabase();
+        db.Execute("FLUSHALL");
+        var bf = db.BF();
+
+        // return 0 if the key does not exist:
+        Assert.Equal(0, bf.Card("notExist"));
+
+        // Store a filter:
+        Assert.True(bf.Add("bf1", "item_foo"));
+        Assert.Equal(1, bf.Card("bf1"));
+
+        // Error when key is of a type other than Bloom filter:
+        db.StringSet("setKey", "value");
+        Assert.Throws<RedisServerException>(() => bf.Card("setKey"));
+    }
+
+    [Fact]
+    public async Task TestCardAsync()
+    {
+        IDatabase db = redisFixture.Redis.GetDatabase();
+        db.Execute("FLUSHALL");
+        var bf = db.BF();
+
+        // return 0 if the key does not exist:
+        Assert.Equal(0, await bf.CardAsync("notExist"));
+
+        // Store a filter:
+        Assert.True(await bf.AddAsync("bf1", "item_foo"));
+        Assert.Equal(1, await bf.CardAsync("bf1"));
+
+        // Error when key is of a type other than Bloom filter:
+        db.StringSet("setKey", "value");
+        await Assert.ThrowsAsync<RedisServerException>(() => bf.CardAsync("setKey"));
+    }
+
     [Fact]
     public void TestModulePrefixs1()
     {