change more string commands to have CommandFunction support (#5184)

* CommandFunction now supports getrange, setrange, bitcount, bitop, bitpos, getbit, setbit, incrbyfloat, mget, and strlen.

Added integration test coverage for untested string commands.

geode-redis/src/integrationTest/java/org/apache/geode/redis/sets/SetsIntegrationTest.java

@@ -15,8 +15,10 @@
 package org.apache.geode.redis.sets;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
 
 import java.util.HashSet;
+import java.util.List;
 import java.util.Set;
 import java.util.concurrent.Callable;
 import java.util.concurrent.ExecutionException;
@@ -178,6 +180,47 @@ private int doABunchOfSAdds(String key, String[] strings,
     return successes;
   }
 
+  @Test
+  public void srandmember_withStringFails() {
+    jedis.set("string", "value");
+    assertThatThrownBy(() -> jedis.srandmember("string")).hasMessageContaining("WRONGTYPE");
+  }
+
+  @Test
+  public void srandmember_withNonExistentKeyReturnsNull() {
+    assertThat(jedis.srandmember("non existent")).isNull();
+  }
+
+  @Test
+  public void srandmemberCount_withNonExistentKeyReturnsEmptyArray() {
+    assertThat(jedis.srandmember("non existent", 3)).isEmpty();
+  }
+
+  @Test
+  public void srandmember_returnsOneMember() {
+    jedis.sadd("key", "m1", "m2");
+    String result = jedis.srandmember("key");
+    assertThat(result).isIn("m1", "m2");
+  }
+
+  @Test
+  public void srandmemberCount_returnsTwoUniqueMembers() {
+    jedis.sadd("key", "m1", "m2", "m3");
+    List<String> results = jedis.srandmember("key", 2);
+    assertThat(results).hasSize(2);
+    assertThat(results).containsAnyOf("m1", "m2", "m3");
+    assertThat(results.get(0)).isNotEqualTo(results.get(1));
+  }
+
+  @Test
+  public void srandmemberCount_returnsTwoMembers() {
+    jedis.sadd("key", "m1", "m2", "m3");
+    List<String> results = jedis.srandmember("key", -3);
+    assertThat(results).hasSize(3);
+    assertThat(results).containsAnyOf("m1", "m2", "m3");
+  }
+
+
   @Test
   public void testSMembersSIsMember() {
     int elements = 10;

geode-redis/src/main/java/org/apache/geode/redis/internal/data/RedisSet.java

@@ -122,6 +122,10 @@ Collection<ByteArrayWrapper> spop(
 
   Collection<ByteArrayWrapper> srandmember(int count) {
     int membersSize = members.size();
+    boolean duplicatesAllowed = count < 0;
+    if (duplicatesAllowed) {
+      count = -count;
+    }
 
     if (membersSize <= count && count != 1) {
       return new ArrayList<>(members);
@@ -138,14 +142,23 @@ Collection<ByteArrayWrapper> srandmember(int count) {
       result.add(randEntry);
       return result;
     }
-    Set<ByteArrayWrapper> result = new HashSet<>();
-    // 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) {
-      ByteArrayWrapper s = entries[rand.nextInt(entries.length)];
-      result.add(s);
+    if (duplicatesAllowed) {
+      ArrayList<ByteArrayWrapper> result = new ArrayList<>(count);
+      while (count > 0) {
+        result.add(entries[rand.nextInt(entries.length)]);
+        count--;
+      }
+      return result;
+    } else {
+      Set<ByteArrayWrapper> result = new HashSet<>();
+      // 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) {
+        ByteArrayWrapper s = entries[rand.nextInt(entries.length)];
+        result.add(s);
+      }
+      return result;
     }
-    return result;
   }
 
   public boolean sismember(ByteArrayWrapper member) {