[GitHub] [geode] DonalEvans commented on a change in pull request #7228: feature/GEODE-9834: SRANDMEMBER Command Support

[GitBox <gi...@apache.org>]

DonalEvans commented on a change in pull request #7228:
URL: https://github.com/apache/geode/pull/7228#discussion_r777743456



##########
File path: geode-for-redis/src/main/java/org/apache/geode/redis/internal/data/collections/SizeableObjectOpenCustomHashSet.java
##########
@@ -62,6 +62,15 @@ public boolean remove(Object k) {
     return removed;
   }
 
+  public K getKey(final int pos) {
+    K member = key[pos];
+    return member;

Review comment:
       This can be simplified to just `return key[pos];`

##########
File path: geode-for-redis/src/integrationTest/java/org/apache/geode/redis/internal/commands/executor/set/AbstractSRandMemberIntegrationTest.java
##########
@@ -0,0 +1,139 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more contributor license
+ * agreements. See the NOTICE file distributed with this work for additional information regarding
+ * copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the License. You may obtain a
+ * copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License
+ * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ * or implied. See the License for the specific language governing permissions and limitations under
+ * the License.
+ */
+package org.apache.geode.redis.internal.commands.executor.set;
+
+import static org.apache.geode.redis.RedisCommandArgumentsTestHelper.assertAtLeastNArgs;
+import static org.apache.geode.redis.internal.RedisConstants.ERROR_NOT_INTEGER;
+import static org.apache.geode.redis.internal.RedisConstants.ERROR_SYNTAX;
+import static org.apache.geode.redis.internal.RedisConstants.ERROR_WRONG_TYPE;
+import static org.apache.geode.test.dunit.rules.RedisClusterStartupRule.BIND_ADDRESS;
+import static org.apache.geode.test.dunit.rules.RedisClusterStartupRule.REDIS_CLIENT_TIMEOUT;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+import java.util.Arrays;
+import java.util.List;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import redis.clients.jedis.HostAndPort;
+import redis.clients.jedis.JedisCluster;
+import redis.clients.jedis.Protocol;
+
+import org.apache.geode.redis.RedisIntegrationTest;
+
+public abstract class AbstractSRandMemberIntegrationTest implements RedisIntegrationTest {
+  private JedisCluster jedis;
+  private static final String nonExistentSetKey = "{user1}nonExistentSet";
+  private static final String setKey = "{user1}setKey";
+  private static final String[] setMembers = {"one", "two", "three", "four", "five"};
+
+  @Before
+  public void setUp() {
+    jedis = new JedisCluster(new HostAndPort(BIND_ADDRESS, getPort()), REDIS_CLIENT_TIMEOUT);
+  }
+
+  @After
+  public void tearDown() {
+    flushAll();
+    jedis.close();
+  }
+
+  @Test
+  public void srandmemberTooFewArgs_returnsError() {
+    assertAtLeastNArgs(jedis, Protocol.Command.SRANDMEMBER, 1);
+  }
+
+  @Test
+  public void srandmemberTooManyArgs_returnsError() {
+    assertThatThrownBy(
+        () -> jedis.sendCommand(setKey, Protocol.Command.SRANDMEMBER, setKey, "5", "5"))
+            .hasMessageContaining(ERROR_SYNTAX);
+  }
+
+  @Test
+  public void srandmemberWithInvalidCount_returnsError() {
+    assertThatThrownBy(() -> jedis.sendCommand(setKey, Protocol.Command.SRANDMEMBER, setKey, "b"))
+        .hasMessageContaining(ERROR_NOT_INTEGER);
+  }
+
+  @Test
+  public void srandmemberWithoutCount_withNonExistentSet_returnsNull() {
+    assertThat(jedis.srandmember(nonExistentSetKey)).isNull();
+    assertThat(jedis.exists(nonExistentSetKey)).isFalse();
+  }
+
+  @Test
+  public void srandmemberWithCount_withNonExistentSet_returnsEmptySet() {
+    assertThat(jedis.srandmember(nonExistentSetKey, 1)).isEmpty();
+    assertThat(jedis.exists(nonExistentSetKey)).isFalse();
+  }
+
+  @Test
+  public void srandmemberWithoutCount_withExistentSet_returnsOneMember() {
+    jedis.sadd(setKey, setMembers);
+
+    String result = jedis.srandmember(setKey);
+    assertThat(setMembers).contains(result);
+  }
+
+  @Test
+  public void srandmemberWithCount_withExistentSet_returnsEmptySet() {

Review comment:
       This test name is incorrect. It should probably be "srandmemberWithCount_withExistentSet_returnsCorrectNumberOfMembers".
   
   It would also be good to have a test showing that when count is positive and larger than the size of the set, no duplicate entries are returned.

##########
File path: geode-for-redis/src/main/java/org/apache/geode/redis/internal/data/RedisSet.java
##########
@@ -161,49 +162,38 @@ public RedisSet() {}
     return popped;
   }
 
-  public Collection<byte[]> srandmember(int count) {
-    int membersSize = members.size();
+  public List<byte[]> srandmember(int count) {
     boolean duplicatesAllowed = count < 0;
-    if (duplicatesAllowed) {
-      count = -count;
-    }
-
-    if (!duplicatesAllowed && membersSize <= count && count != 1) {
-      return new ArrayList<>(members);
-    }
+    count = duplicatesAllowed ? -count : count;
+    int membersSize = members.size();
+    int memberMapSize = members.getMemberMapSize();
 
     Random rand = new Random();
-
-    // TODO: this could be optimized to take advantage of MemberSet
-    // storing its data in an array. We probably don't need to copy it
-    // into another array here.
-    byte[][] entries = members.toArray(new byte[membersSize][]);
-
-    if (count == 1) {
-      byte[] randEntry = entries[rand.nextInt(entries.length)];
-      // TODO: Now that the result is no longer serialized this could use singleton.
-      // Note using ArrayList because Collections.singleton has serialization issues.
-      List<byte[]> result = new ArrayList<>(1);
-      result.add(randEntry);
-      return result;
-    }
-    if (duplicatesAllowed) {
-      List<byte[]> result = new ArrayList<>(count);
-      while (count > 0) {
-        result.add(entries[rand.nextInt(entries.length)]);
-        count--;
-      }
-      return result;
+    List<byte[]> result = new ArrayList<>(count);
+    if (!duplicatesAllowed && membersSize <= count) {
+      result.addAll(members);
     } else {
-      Set<byte[]> result = new MemberSet(count);
-      // Note that rand.nextInt can return duplicates when "count" is high
-      // so we need to use a Set to collect the results.
-      while (result.size() < count) {
-        byte[] s = entries[rand.nextInt(entries.length)];
-        result.add(s);
+      Set<Integer> usedIndexes = null;
+      if (!duplicatesAllowed) {
+        usedIndexes = new HashSet<>(count);
+      }
+
+      for (int i = 0; i < count; i++) {
+        int randIndex = rand.nextInt(memberMapSize);
+        byte[] member = members.getKeyAtIndex(randIndex);
+
+        while (member == null || (!duplicatesAllowed && usedIndexes.contains(randIndex))) {

Review comment:
       This loop could end up taking a long time to execute if `members` is large, duplicates are not allowed and `count` is close to `members.size()`, as it requires generating a random number that isn't the same as any of the previously generated numbers. Including the outer for loop, this ends up making the srandmember command execute in O(N^2) (or thereabouts) which is not in line with native Redis' quoted complexity of O(N).
   
   For the no duplicates case, native Redis uses a different implementation where, if count is greater than 1/3 of the size of the member set, they instead create a duplicate of the entire set and then remove members from it at random until it has the correct size.  From t_set.c (SRANDMEMBER_SUB_STRATEGY_MUL is defined as 3):
   >    /* CASE 3:
        * The number of elements inside the set is not greater than
        * SRANDMEMBER_SUB_STRATEGY_MUL times the number of requested elements.
        * In this case we create a set from scratch with all the elements, and
        * subtract random elements to reach the requested number of elements.
        *
        * This is done because if the number of requested elements is just
        * a bit less than the number of elements in the set, the natural approach
        * used into CASE 4 is highly inefficient. */
   
   It's possible that there's a better approach than this, but it's an improvement over the current one, at least.

##########
File path: geode-for-redis/src/integrationTest/java/org/apache/geode/redis/internal/commands/executor/set/AbstractSRandMemberIntegrationTest.java
##########
@@ -0,0 +1,139 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more contributor license
+ * agreements. See the NOTICE file distributed with this work for additional information regarding
+ * copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the License. You may obtain a
+ * copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License
+ * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ * or implied. See the License for the specific language governing permissions and limitations under
+ * the License.
+ */
+package org.apache.geode.redis.internal.commands.executor.set;
+
+import static org.apache.geode.redis.RedisCommandArgumentsTestHelper.assertAtLeastNArgs;
+import static org.apache.geode.redis.internal.RedisConstants.ERROR_NOT_INTEGER;
+import static org.apache.geode.redis.internal.RedisConstants.ERROR_SYNTAX;
+import static org.apache.geode.redis.internal.RedisConstants.ERROR_WRONG_TYPE;
+import static org.apache.geode.test.dunit.rules.RedisClusterStartupRule.BIND_ADDRESS;
+import static org.apache.geode.test.dunit.rules.RedisClusterStartupRule.REDIS_CLIENT_TIMEOUT;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+import java.util.Arrays;
+import java.util.List;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import redis.clients.jedis.HostAndPort;
+import redis.clients.jedis.JedisCluster;
+import redis.clients.jedis.Protocol;
+
+import org.apache.geode.redis.RedisIntegrationTest;
+
+public abstract class AbstractSRandMemberIntegrationTest implements RedisIntegrationTest {
+  private JedisCluster jedis;
+  private static final String nonExistentSetKey = "{user1}nonExistentSet";
+  private static final String setKey = "{user1}setKey";
+  private static final String[] setMembers = {"one", "two", "three", "four", "five"};
+
+  @Before
+  public void setUp() {
+    jedis = new JedisCluster(new HostAndPort(BIND_ADDRESS, getPort()), REDIS_CLIENT_TIMEOUT);
+  }
+
+  @After
+  public void tearDown() {
+    flushAll();
+    jedis.close();
+  }
+
+  @Test
+  public void srandmemberTooFewArgs_returnsError() {
+    assertAtLeastNArgs(jedis, Protocol.Command.SRANDMEMBER, 1);
+  }
+
+  @Test
+  public void srandmemberTooManyArgs_returnsError() {
+    assertThatThrownBy(
+        () -> jedis.sendCommand(setKey, Protocol.Command.SRANDMEMBER, setKey, "5", "5"))
+            .hasMessageContaining(ERROR_SYNTAX);
+  }
+
+  @Test
+  public void srandmemberWithInvalidCount_returnsError() {
+    assertThatThrownBy(() -> jedis.sendCommand(setKey, Protocol.Command.SRANDMEMBER, setKey, "b"))
+        .hasMessageContaining(ERROR_NOT_INTEGER);
+  }
+
+  @Test
+  public void srandmemberWithoutCount_withNonExistentSet_returnsNull() {
+    assertThat(jedis.srandmember(nonExistentSetKey)).isNull();
+    assertThat(jedis.exists(nonExistentSetKey)).isFalse();
+  }
+
+  @Test
+  public void srandmemberWithCount_withNonExistentSet_returnsEmptySet() {
+    assertThat(jedis.srandmember(nonExistentSetKey, 1)).isEmpty();
+    assertThat(jedis.exists(nonExistentSetKey)).isFalse();
+  }
+
+  @Test
+  public void srandmemberWithoutCount_withExistentSet_returnsOneMember() {
+    jedis.sadd(setKey, setMembers);
+
+    String result = jedis.srandmember(setKey);
+    assertThat(setMembers).contains(result);
+  }
+
+  @Test
+  public void srandmemberWithCount_withExistentSet_returnsEmptySet() {
+    jedis.sadd(setKey, setMembers);
+    int count = 2;
+
+    List<String> result = jedis.srandmember(setKey, count);
+    assertThat(result.size()).isEqualTo(2);
+    assertThat(result).containsAnyElementsOf(Arrays.asList(setMembers));

Review comment:
       This assertion is only testing that `result` contains at least one element found in `setMembers`. The correct assertion to use here would be `isSubsetOf(setMembers)`, along with `assertThat(result).doesNotHaveDuplicates()` to ensure that only unique members are returned.

##########
File path: geode-for-redis/src/main/java/org/apache/geode/redis/internal/commands/executor/set/SetRandomExecutor.java
##########
@@ -0,0 +1,74 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more contributor license
+ * agreements. See the NOTICE file distributed with this work for additional information regarding
+ * copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the License. You may obtain a
+ * copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License
+ * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ * or implied. See the License for the specific language governing permissions and limitations under
+ * the License.
+ */
+package org.apache.geode.redis.internal.commands.executor.set;
+
+import static org.apache.geode.redis.internal.RedisConstants.ERROR_NOT_INTEGER;
+import static org.apache.geode.redis.internal.data.RedisDataType.REDIS_SET;
+import static org.apache.geode.redis.internal.netty.Coder.bytesToLong;
+import static org.apache.geode.redis.internal.netty.Coder.narrowLongToInt;
+
+import java.util.Collections;
+import java.util.List;
+
+import org.apache.geode.redis.internal.commands.Command;
+import org.apache.geode.redis.internal.commands.executor.CommandExecutor;
+import org.apache.geode.redis.internal.commands.executor.RedisResponse;
+import org.apache.geode.redis.internal.data.RedisKey;
+import org.apache.geode.redis.internal.data.RedisSet;
+import org.apache.geode.redis.internal.netty.ExecutionHandlerContext;
+import org.apache.geode.redis.internal.services.RegionProvider;
+
+public abstract class SetRandomExecutor implements CommandExecutor {

Review comment:
       Does this class need to exist? It's only used by the `SRandMemberExecutor`, and as far as I can tell, there aren't any other currently unsupported Redis set commands that would also use this class but implement a different `performCommand()` method. Could these two classes just be combined into `SRandMemberExecutor`?

##########
File path: geode-for-redis/src/integrationTest/java/org/apache/geode/redis/internal/commands/executor/set/AbstractSRandMemberIntegrationTest.java
##########
@@ -0,0 +1,139 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more contributor license
+ * agreements. See the NOTICE file distributed with this work for additional information regarding
+ * copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the License. You may obtain a
+ * copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License
+ * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ * or implied. See the License for the specific language governing permissions and limitations under
+ * the License.
+ */
+package org.apache.geode.redis.internal.commands.executor.set;
+
+import static org.apache.geode.redis.RedisCommandArgumentsTestHelper.assertAtLeastNArgs;
+import static org.apache.geode.redis.internal.RedisConstants.ERROR_NOT_INTEGER;
+import static org.apache.geode.redis.internal.RedisConstants.ERROR_SYNTAX;
+import static org.apache.geode.redis.internal.RedisConstants.ERROR_WRONG_TYPE;
+import static org.apache.geode.test.dunit.rules.RedisClusterStartupRule.BIND_ADDRESS;
+import static org.apache.geode.test.dunit.rules.RedisClusterStartupRule.REDIS_CLIENT_TIMEOUT;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+import java.util.Arrays;
+import java.util.List;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import redis.clients.jedis.HostAndPort;
+import redis.clients.jedis.JedisCluster;
+import redis.clients.jedis.Protocol;
+
+import org.apache.geode.redis.RedisIntegrationTest;
+
+public abstract class AbstractSRandMemberIntegrationTest implements RedisIntegrationTest {
+  private JedisCluster jedis;
+  private static final String nonExistentSetKey = "{user1}nonExistentSet";
+  private static final String setKey = "{user1}setKey";
+  private static final String[] setMembers = {"one", "two", "three", "four", "five"};
+
+  @Before
+  public void setUp() {
+    jedis = new JedisCluster(new HostAndPort(BIND_ADDRESS, getPort()), REDIS_CLIENT_TIMEOUT);
+  }
+
+  @After
+  public void tearDown() {
+    flushAll();
+    jedis.close();
+  }
+
+  @Test
+  public void srandmemberTooFewArgs_returnsError() {
+    assertAtLeastNArgs(jedis, Protocol.Command.SRANDMEMBER, 1);
+  }
+
+  @Test
+  public void srandmemberTooManyArgs_returnsError() {
+    assertThatThrownBy(
+        () -> jedis.sendCommand(setKey, Protocol.Command.SRANDMEMBER, setKey, "5", "5"))
+            .hasMessageContaining(ERROR_SYNTAX);
+  }
+
+  @Test
+  public void srandmemberWithInvalidCount_returnsError() {
+    assertThatThrownBy(() -> jedis.sendCommand(setKey, Protocol.Command.SRANDMEMBER, setKey, "b"))
+        .hasMessageContaining(ERROR_NOT_INTEGER);
+  }
+
+  @Test
+  public void srandmemberWithoutCount_withNonExistentSet_returnsNull() {
+    assertThat(jedis.srandmember(nonExistentSetKey)).isNull();
+    assertThat(jedis.exists(nonExistentSetKey)).isFalse();
+  }
+
+  @Test
+  public void srandmemberWithCount_withNonExistentSet_returnsEmptySet() {
+    assertThat(jedis.srandmember(nonExistentSetKey, 1)).isEmpty();
+    assertThat(jedis.exists(nonExistentSetKey)).isFalse();
+  }
+
+  @Test
+  public void srandmemberWithoutCount_withExistentSet_returnsOneMember() {
+    jedis.sadd(setKey, setMembers);
+
+    String result = jedis.srandmember(setKey);
+    assertThat(setMembers).contains(result);
+  }
+
+  @Test
+  public void srandmemberWithCount_withExistentSet_returnsEmptySet() {
+    jedis.sadd(setKey, setMembers);
+    int count = 2;
+
+    List<String> result = jedis.srandmember(setKey, count);
+    assertThat(result.size()).isEqualTo(2);
+    assertThat(result).containsAnyElementsOf(Arrays.asList(setMembers));
+  }
+
+  @Test
+  public void srandmemberWithCountAsSetSize_withExistentSet_returnsAllMembers() {
+    jedis.sadd(setKey, setMembers);
+    int count = setMembers.length;
+
+    List<String> result = jedis.srandmember(setKey, count);
+    assertThat(result.size()).isEqualTo(count);
+    assertThat(result).containsExactlyInAnyOrder(setMembers);
+  }
+
+  @Test
+  public void srandmemberWithCountAsGreaterThanSetSize_withExistentSet_returnsAllMembersWithDuplicates() {
+    jedis.sadd(setKey, setMembers);
+    int count = -20;
+
+    List<String> result = jedis.srandmember(setKey, count);
+    assertThat(result.size()).isEqualTo(-count);
+    for (String s : result) {
+      assertThat(s).isNotNull();
+      assertThat(setMembers).contains(s);
+    }

Review comment:
       This can be simplified to:
   ```
   assertThat(result).isSubsetOf(setMembers);
   ```

##########
File path: geode-for-redis/src/main/java/org/apache/geode/redis/internal/data/RedisSet.java
##########
@@ -161,49 +162,38 @@ public RedisSet() {}
     return popped;
   }
 
-  public Collection<byte[]> srandmember(int count) {
-    int membersSize = members.size();
+  public List<byte[]> srandmember(int count) {
     boolean duplicatesAllowed = count < 0;
-    if (duplicatesAllowed) {
-      count = -count;
-    }
-
-    if (!duplicatesAllowed && membersSize <= count && count != 1) {
-      return new ArrayList<>(members);
-    }
+    count = duplicatesAllowed ? -count : count;
+    int membersSize = members.size();
+    int memberMapSize = members.getMemberMapSize();
 
     Random rand = new Random();

Review comment:
       Rather than creating a new `Random` instance each time this command is executed, it might be better to create a final field on the class so that it only needs to be instantiated once.

##########
File path: geode-for-redis/src/integrationTest/java/org/apache/geode/redis/internal/commands/executor/set/AbstractSRandMemberIntegrationTest.java
##########
@@ -0,0 +1,139 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more contributor license
+ * agreements. See the NOTICE file distributed with this work for additional information regarding
+ * copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the License. You may obtain a
+ * copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License
+ * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ * or implied. See the License for the specific language governing permissions and limitations under
+ * the License.
+ */
+package org.apache.geode.redis.internal.commands.executor.set;
+
+import static org.apache.geode.redis.RedisCommandArgumentsTestHelper.assertAtLeastNArgs;
+import static org.apache.geode.redis.internal.RedisConstants.ERROR_NOT_INTEGER;
+import static org.apache.geode.redis.internal.RedisConstants.ERROR_SYNTAX;
+import static org.apache.geode.redis.internal.RedisConstants.ERROR_WRONG_TYPE;
+import static org.apache.geode.test.dunit.rules.RedisClusterStartupRule.BIND_ADDRESS;
+import static org.apache.geode.test.dunit.rules.RedisClusterStartupRule.REDIS_CLIENT_TIMEOUT;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+import java.util.Arrays;
+import java.util.List;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import redis.clients.jedis.HostAndPort;
+import redis.clients.jedis.JedisCluster;
+import redis.clients.jedis.Protocol;
+
+import org.apache.geode.redis.RedisIntegrationTest;
+
+public abstract class AbstractSRandMemberIntegrationTest implements RedisIntegrationTest {
+  private JedisCluster jedis;
+  private static final String nonExistentSetKey = "{user1}nonExistentSet";
+  private static final String setKey = "{user1}setKey";
+  private static final String[] setMembers = {"one", "two", "three", "four", "five"};
+
+  @Before
+  public void setUp() {
+    jedis = new JedisCluster(new HostAndPort(BIND_ADDRESS, getPort()), REDIS_CLIENT_TIMEOUT);
+  }
+
+  @After
+  public void tearDown() {
+    flushAll();
+    jedis.close();
+  }
+
+  @Test
+  public void srandmemberTooFewArgs_returnsError() {
+    assertAtLeastNArgs(jedis, Protocol.Command.SRANDMEMBER, 1);
+  }
+
+  @Test
+  public void srandmemberTooManyArgs_returnsError() {
+    assertThatThrownBy(
+        () -> jedis.sendCommand(setKey, Protocol.Command.SRANDMEMBER, setKey, "5", "5"))
+            .hasMessageContaining(ERROR_SYNTAX);
+  }
+
+  @Test
+  public void srandmemberWithInvalidCount_returnsError() {
+    assertThatThrownBy(() -> jedis.sendCommand(setKey, Protocol.Command.SRANDMEMBER, setKey, "b"))
+        .hasMessageContaining(ERROR_NOT_INTEGER);
+  }
+
+  @Test
+  public void srandmemberWithoutCount_withNonExistentSet_returnsNull() {
+    assertThat(jedis.srandmember(nonExistentSetKey)).isNull();
+    assertThat(jedis.exists(nonExistentSetKey)).isFalse();
+  }
+
+  @Test
+  public void srandmemberWithCount_withNonExistentSet_returnsEmptySet() {
+    assertThat(jedis.srandmember(nonExistentSetKey, 1)).isEmpty();
+    assertThat(jedis.exists(nonExistentSetKey)).isFalse();
+  }
+
+  @Test
+  public void srandmemberWithoutCount_withExistentSet_returnsOneMember() {
+    jedis.sadd(setKey, setMembers);
+
+    String result = jedis.srandmember(setKey);
+    assertThat(setMembers).contains(result);
+  }
+
+  @Test
+  public void srandmemberWithCount_withExistentSet_returnsEmptySet() {
+    jedis.sadd(setKey, setMembers);
+    int count = 2;
+
+    List<String> result = jedis.srandmember(setKey, count);
+    assertThat(result.size()).isEqualTo(2);
+    assertThat(result).containsAnyElementsOf(Arrays.asList(setMembers));
+  }
+
+  @Test
+  public void srandmemberWithCountAsSetSize_withExistentSet_returnsAllMembers() {
+    jedis.sadd(setKey, setMembers);
+    int count = setMembers.length;
+
+    List<String> result = jedis.srandmember(setKey, count);
+    assertThat(result.size()).isEqualTo(count);
+    assertThat(result).containsExactlyInAnyOrder(setMembers);
+  }
+
+  @Test
+  public void srandmemberWithCountAsGreaterThanSetSize_withExistentSet_returnsAllMembersWithDuplicates() {

Review comment:
       This test name is a little misleading, as the test is actually testing a negative count value, not a count that is greater than the set size.




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