Add HSTRLEN command implementation and testing

src/StackExchange.Redis/Enums/RedisCommand.cs

@@ -65,6 +65,7 @@ internal enum RedisCommand
         HSCAN,
         HSET,
         HSETNX,
+        HSTRLEN,
         HVALS,
 
         INCR,

src/StackExchange.Redis/Interfaces/IDatabase.cs

@@ -358,6 +358,16 @@ public interface IDatabase : IRedis, IDatabaseAsync
         /// <remarks>https://redis.io/commands/hsetnx</remarks>
         bool HashSet(RedisKey key, RedisValue hashField, RedisValue value, When when = When.Always, CommandFlags flags = CommandFlags.None);
 
+        /// <summary>
+        /// Returns the string length of the value associated with field in the hash stored at key.
+        /// </summary>
+        /// <param name="key">The key of the hash.</param>
+        /// <param name="hashField">The field containing the string</param>
+        /// <param name="flags">The flags to use for this operation.</param>
+        /// <returns>the length of the string at field, or 0 when key does not exist.</returns>
+        /// <remarks>https://redis.io/commands/hstrlen</remarks>
+        long HashStringLength(RedisKey key, RedisValue hashField, CommandFlags flags = CommandFlags.None);
+
         /// <summary>
         /// Returns all values in the hash stored at key.
         /// </summary>

src/StackExchange.Redis/Interfaces/IDatabaseAsync.cs

@@ -322,6 +322,16 @@ public interface IDatabaseAsync : IRedisAsync
         /// <remarks>https://redis.io/commands/hsetnx</remarks>
         Task<bool> HashSetAsync(RedisKey key, RedisValue hashField, RedisValue value, When when = When.Always, CommandFlags flags = CommandFlags.None);
 
+        /// <summary>
+        /// Returns the string length of the value associated with field in the hash stored at key.
+        /// </summary>
+        /// <param name="key">The key of the hash.</param>
+        /// <param name="hashField">The field containing the string</param>
+        /// <param name="flags">The flags to use for this operation.</param>
+        /// <returns>the length of the string at field, or 0 when key does not exist.</returns>
+        /// <remarks>https://redis.io/commands/hstrlen</remarks>
+        Task<long> HashStringLengthAsync(RedisKey key, RedisValue hashField, CommandFlags flags = CommandFlags.None);
+
         /// <summary>
         /// Returns all values in the hash stored at key.
         /// </summary>

src/StackExchange.Redis/KeyspaceIsolation/DatabaseWrapper.cs

@@ -152,6 +152,11 @@ public bool HashSet(RedisKey key, RedisValue hashField, RedisValue value, When w
             return Inner.HashSet(ToInner(key), hashField, value, when, flags);
         }
 
+        public long HashStringLength(RedisKey key, RedisValue hashField, CommandFlags flags = CommandFlags.None)
+        {
+            return Inner.HashStringLength(ToInner(key), hashField, flags);
+        }
+
         public void HashSet(RedisKey key, HashEntry[] hashFields, CommandFlags flags = CommandFlags.None)
         {
             Inner.HashSet(ToInner(key), hashFields, flags);

src/StackExchange.Redis/KeyspaceIsolation/WrapperBase.cs

@@ -128,6 +128,11 @@ public Task<bool> HashSetAsync(RedisKey key, RedisValue hashField, RedisValue va
             return Inner.HashSetAsync(ToInner(key), hashField, value, when, flags);
         }
 
+        public Task<long> HashStringLengthAsync(RedisKey key, RedisValue hashField, CommandFlags flags = CommandFlags.None)
+        {
+            return Inner.HashStringLengthAsync(ToInner(key), hashField, flags);
+        }
+
         public Task HashSetAsync(RedisKey key, HashEntry[] hashFields, CommandFlags flags = CommandFlags.None)
         {
             return Inner.HashSetAsync(ToInner(key), hashFields, flags);

src/StackExchange.Redis/RedisDatabase.cs

@@ -438,6 +438,13 @@ public void HashSet(RedisKey key, HashEntry[] hashFields, CommandFlags flags = C
             ExecuteSync(msg, ResultProcessor.DemandOK);
         }
 
+        public long HashStringLength(RedisKey key, RedisValue hashField, CommandFlags flags = CommandFlags.None)
+        {
+            var msg = Message.Create(Database, flags, RedisCommand.HSTRLEN, key, hashField);
+            return ExecuteSync(msg, ResultProcessor.Int64);
+        }
+
+
         public Task<bool> HashSetAsync(RedisKey key, RedisValue hashField, RedisValue value, When when = When.Always, CommandFlags flags = CommandFlags.None)
         {
             WhenAlwaysOrNotExists(when);
@@ -447,6 +454,12 @@ public Task<bool> HashSetAsync(RedisKey key, RedisValue hashField, RedisValue va
             return ExecuteAsync(msg, ResultProcessor.Boolean);
         }
 
+        public Task<long> HashStringLengthAsync(RedisKey key, RedisValue hashField, CommandFlags flags = CommandFlags.None)
+        {
+            var msg = Message.Create(Database, flags, RedisCommand.HSTRLEN, key, hashField);
+            return ExecuteAsync(msg, ResultProcessor.Int64);
+        }
+
         public Task HashSetAsync(RedisKey key, HashEntry[] hashFields, CommandFlags flags = CommandFlags.None)
         {
             var msg = GetHashSetMessage(key, hashFields, flags);

src/StackExchange.Redis/RedisFeatures.cs

@@ -65,6 +65,11 @@ public RedisFeatures(Version version)
         /// </summary>
         public bool ExpireOverwrite => Version >= v2_1_3;
 
+        /// <summary>
+        /// Is HSTRLEN available?
+        /// </summary>
+        public bool HashStringLength => Version >= v3_2_0;
+
         /// <summary>
         /// Does HDEL support varadic usage?
         /// </summary>

tests/StackExchange.Redis.Tests/DatabaseWrapperTests.cs

@@ -166,6 +166,13 @@ public void HashSet_2()
             mock.Verify(_ => _.HashSet("prefix:key", "hashField", "value", When.Exists, CommandFlags.None));
         }
 
+        [Fact]
+        public void HashStringLength()
+        {
+            wrapper.HashStringLength("key","field", CommandFlags.None);
+            mock.Verify(_ => _.HashStringLength("prefix:key", "field", CommandFlags.None));
+        }
+
         [Fact]
         public void HashValues()
         {

tests/StackExchange.Redis.Tests/Strings.cs

@@ -304,6 +304,22 @@ public async Task RangeString()
             }
         }
 
+        [Fact]
+        public void HashStringLength()
+        {
+            using (var conn = Create())
+            {
+                Skip.IfMissingFeature(conn, nameof(RedisFeatures.HashStringLength), r => r.HashStringLength);
+                var database = conn.GetDatabase();
+                var key = Me();
+                var value = "hello world";
+                database.HashSet(key, "field", value);
+
+                Assert.Equal(value.Length, database.HashStringLength(key, "field"));
+                Assert.Equal(0, database.HashStringLength(key, "non-existing-field"));
+            }
+        }
+
         private static byte[] Encode(string value) => Encoding.UTF8.GetBytes(value);
         private static string Decode(byte[] value) => Encoding.UTF8.GetString(value);
     }

tests/StackExchange.Redis.Tests/WrapperBaseTests.cs

@@ -130,7 +130,14 @@ public void HashSetAsync_2()
             wrapper.HashSetAsync("key", "hashField", "value", When.Exists, CommandFlags.None);
             mock.Verify(_ => _.HashSetAsync("prefix:key", "hashField", "value", When.Exists, CommandFlags.None));
         }
-
+
+        [Fact]
+        public void HashStringLengthAsync()
+        {
+            wrapper.HashStringLengthAsync("key","field", CommandFlags.None);
+            mock.Verify(_ => _.HashStringLengthAsync("prefix:key", "field", CommandFlags.None));
+        }
+
         [Fact]
         public void HashValuesAsync()
         {