[Redis 6.2] Add ZRANDMEMBER command

lib/redis.rb

@@ -1897,6 +1897,46 @@ def zmscore(key, *members)
     end
   end
 
+  # Get one or more random members from a sorted set.
+  #
+  # @example Get one random member
+  #   redis.zrandmember("zset")
+  #     # => "a"
+  # @example Get multiple random members
+  #   redis.zrandmember("zset", 2)
+  #     # => ["a", "b"]
+  # @example Gem multiple random members with scores
+  #   redis.zrandmember("zset", 2, with_scores: true)
+  #     # => [["a", 2.0], ["b", 3.0]]
+  #
+  # @param [String] key
+  # @param [Integer] count
+  # @param [Hash] options
+  #   - `:with_scores => true`: include scores in output
+  #
+  # @return [nil, String, Array<String>, Array<[String, Float]>]
+  #   - when `key` does not exist or set is empty, `nil`
+  #   - when `count` is not specified, a member
+  #   - when `count` is specified and `:with_scores` is not specified, an array of members
+  #   - when `:with_scores` is specified, an array with `[member, score]` pairs
+  def zrandmember(key, count = nil, withscores: false, with_scores: withscores)
+    if with_scores && count.nil?
+      raise ArgumentError, "count argument must be specified"
+    end
+
+    args = [:zrandmember, key]
+    args << count if count
+
+    if with_scores
+      args << "WITHSCORES"
+      block = FloatifyPairs
+    end
+
+    synchronize do |client|
+      client.call(args, &block)
+    end
+  end
+
   # Return a range of members in a sorted set, by index.
   #
   # @example Retrieve all members from a sorted set

lib/redis/distributed.rb

@@ -656,6 +656,11 @@ def zscore(key, member)
       node_for(key).zscore(key, member)
     end
 
+    # Get one or more random members from a sorted set.
+    def zrandmember(key, count = nil, **options)
+      node_for(key).zrandmember(key, count, **options)
+    end
+
     # Get the scores associated with the given members in a sorted set.
     def zmscore(key, *members)
       node_for(key).zmscore(key, *members)

test/lint/sorted_sets.rb

@@ -358,6 +358,34 @@ def test_zmscore
       end
     end
 
+    def test_zrandmember
+      target_version("6.2") do
+        assert_nil r.zrandmember("foo")
+
+        r.zadd "foo", 1.0, "s1"
+        r.zrem "foo", "s1"
+        assert_nil r.zrandmember("foo")
+        assert_equal [], r.zrandmember("foo", 1)
+
+        r.zadd "foo", 1.0, "s1"
+        r.zadd "foo", 2.0, "s2"
+        r.zadd "foo", 3.0, "s3"
+
+        3.times do
+          assert ["s1", "s2", "s3"].include?(r.zrandmember("foo"))
+        end
+
+        assert_equal 2, r.zrandmember("foo", 2).size
+        assert_equal 3, r.zrandmember("foo", 4).size
+        assert_equal 5, r.zrandmember("foo", -5).size
+
+        r.zrandmember("foo", 2, with_scores: true).each do |(member, score)|
+          assert ["s1", "s2", "s3"].include?(member)
+          assert_instance_of Float, score
+        end
+      end
+    end
+
     def test_zremrangebyrank
       r.zadd "foo", 10, "s1"
       r.zadd "foo", 20, "s2"