Fix RedisCommand.requiresArguments for zero argument length.

Closes #2646
Original Pull Request: #2647

Author: jxblum

src/main/java/org/springframework/data/redis/core/RedisCommand.java

@@ -257,8 +257,8 @@ public static RedisCommand failsafeCommandLookup(String key) {
 	private final boolean read;
 	private final boolean write;
 
-	private final int minArgs;
-	private final int maxArgs;
+	final int minArgs;
+	final int maxArgs;
 
 	private final @Nullable String alias;
 
@@ -313,7 +313,7 @@ public static RedisCommand failsafeCommandLookup(String key) {
 	 * @return {@literal true} if the command requires arguments
 	 */
 	public boolean requiresArguments() {
-		return minArgs >= 0;
+		return minArgs > 0;
 	}
 
 	/**

src/test/java/org/springframework/data/redis/core/RedisCommandUnitTests.java

@@ -17,6 +17,8 @@
 
 import static org.assertj.core.api.Assertions.*;
 
+import java.util.Arrays;
+
 import org.junit.jupiter.api.Test;
 
 /**
@@ -117,4 +119,23 @@ void isRepresentedByIsCorrectForAllCommandsAndTheirAliases() {
 			}
 		}
 	}
+
+	@Test // GH-2646
+	void commandRequiresArgumentsIsCorrect() {
+
+		Arrays.stream(RedisCommand.values()).forEach(command ->
+				assertThat(command.requiresArguments())
+						.describedAs("Redis command [%s] failed required arguments check", command)
+						.isEqualTo(command.minArgs > 0));
+	}
+
+	@Test // GH-2646
+	void commandRequiresExactNumberOfArgumentsIsCorrect() {
+
+		Arrays.stream(RedisCommand.values()).forEach(command ->
+				assertThat(command.requiresExactNumberOfArguments())
+						.describedAs("Redis command [%s] failed requires exact arguments check")
+						.isEqualTo(command.minArgs == command.maxArgs));
+	}
+
 }