diff --git a/pom.xml b/pom.xml
index 9ebd1b5..3c3373a 100644
--- a/pom.xml
+++ b/pom.xml
@@ -38,8 +38,15 @@
             <groupId>org.projectlombok</groupId>
             <artifactId>lombok</artifactId>
             <version>${lombok.version}</version>
+            <scope>compile</scope>
             <optional>true</optional>
         </dependency>
+        <dependency>
+            <groupId>ch.qos.logback</groupId>
+            <artifactId>logback-classic</artifactId>
+            <version>1.2.11</version>
+            <scope>test</scope>
+        </dependency>
 
         <dependency>
             <groupId>org.junit.jupiter</groupId>
@@ -48,4 +55,4 @@
             <scope>test</scope>
         </dependency>
     </dependencies>
-</project>
\ No newline at end of file
+</project>
diff --git a/src/test/java/xyz/zhouxy/plusone/commons/EnumerationTests.java b/src/test/java/xyz/zhouxy/plusone/commons/EnumerationTests.java
index 6e950a7..6e6d552 100644
--- a/src/test/java/xyz/zhouxy/plusone/commons/EnumerationTests.java
+++ b/src/test/java/xyz/zhouxy/plusone/commons/EnumerationTests.java
@@ -2,21 +2,27 @@ package xyz.zhouxy.plusone.commons;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
+import lombok.extern.slf4j.Slf4j;
 import org.junit.jupiter.api.Test;
 
 import xyz.zhouxy.plusone.commons.util.Enumeration;
 
+import javax.annotation.Nonnull;
+import java.util.Collection;
+
+@Slf4j
 class EnumerationTests {
 
     @Test
     void testEnumeration() {
         assertEquals(EntityStatus.AVAILABLE, EntityStatus.of(0));
+        log.info(EntityStatus.constants().toString());
     }
 }
 
 final class EntityStatus extends Enumeration<EntityStatus> {
 
-    private EntityStatus(int value, String name) {
+    private EntityStatus(int value, @Nonnull String name) {
         super(value, name);
     }
 
@@ -24,16 +30,16 @@ final class EntityStatus extends Enumeration<EntityStatus> {
     public static final EntityStatus AVAILABLE = new EntityStatus(0, "正常");
     public static final EntityStatus DISABLED = new EntityStatus(1, "禁用");
 
-    private static final EnumerationValuesHolder<EntityStatus> ENUMERATION_VALUES = new EnumerationValuesHolder<>(
-            AVAILABLE,
-            DISABLED);
+    private static final ValueSet<EntityStatus> ENUMERATION_VALUES = new ValueSet<>(
+            AVAILABLE, DISABLED);
 
+    @Nonnull
     public static EntityStatus of(int value) {
         return ENUMERATION_VALUES.get(value);
     }
 
-    @Override
-    public String toString() {
-        return "EntityStatus" + super.toString();
+    @Nonnull
+    public static Collection<EntityStatus> constants() {
+        return ENUMERATION_VALUES.getValues();
     }
-}
\ No newline at end of file
+}
diff --git a/src/test/java/xyz/zhouxy/plusone/commons/util/NumberUtilTest.java b/src/test/java/xyz/zhouxy/plusone/commons/util/NumberUtilTest.java
index f330013..3c42b12 100644
--- a/src/test/java/xyz/zhouxy/plusone/commons/util/NumberUtilTest.java
+++ b/src/test/java/xyz/zhouxy/plusone/commons/util/NumberUtilTest.java
@@ -3,8 +3,10 @@ package xyz.zhouxy.plusone.commons.util;
 import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
+import lombok.extern.slf4j.Slf4j;
 import org.junit.jupiter.api.Test;
 
+@Slf4j
 class NumberUtilTest {
     @Test
     void testSum() {
@@ -12,24 +14,24 @@ class NumberUtilTest {
         for (int i = 0; i < Integer.MAX_VALUE; i++) {
             result += Short.MAX_VALUE;
         }
-        System.out.println("Integer.MAX_VALUE: " + Integer.MAX_VALUE);
-        System.out.println("result: " + result);
+        log.info("Integer.MAX_VALUE: {}", Integer.MAX_VALUE);
+        log.info("result: {}", result);
         assertFalse(Integer.MAX_VALUE > result);
 
         result = 0;
         for (int i = 0; i < Integer.MAX_VALUE; i++) {
             result += Short.MAX_VALUE;
         }
-        System.out.println("Long.MAX_VALUE: " + Long.MAX_VALUE);
-        System.out.println("result: " + result);
+        log.info("Long.MAX_VALUE: {}", Long.MAX_VALUE);
+        log.info("result: {}", result);
         assertTrue(Long.MAX_VALUE > result);
 
         result = 0;
         for (int i = 0; i < Integer.MAX_VALUE; i++) {
             result += Integer.MAX_VALUE;
         }
-        System.out.println("Long.MAX_VALUE: " + Long.MAX_VALUE);
-        System.out.println("result: " + result);
+        log.info("Long.MAX_VALUE: {}", Long.MAX_VALUE);
+        log.info("result: {}", result);
         assertTrue(Long.MAX_VALUE > result);
     }
 }
diff --git a/src/test/java/xyz/zhouxy/plusone/commons/util/RestfulResultTest.java b/src/test/java/xyz/zhouxy/plusone/commons/util/RestfulResultTest.java
index 177d05a..6255a67 100644
--- a/src/test/java/xyz/zhouxy/plusone/commons/util/RestfulResultTest.java
+++ b/src/test/java/xyz/zhouxy/plusone/commons/util/RestfulResultTest.java
@@ -2,8 +2,10 @@ package xyz.zhouxy.plusone.commons.util;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
+import lombok.extern.slf4j.Slf4j;
 import org.junit.jupiter.api.Test;
 
+@Slf4j
 class RestfulResultTest {
 
     @Test
@@ -11,24 +13,24 @@ class RestfulResultTest {
         String str = null;
         RestfulResult result = RestfulResult.successIf(str != null, "成功")
                 .orError();
-        System.out.println(result);
+        log.info(result.toString());
         assertEquals(RestfulResult.DEFAULT_ERROR_STATUS, result.getStatus());
 
         result = RestfulResult.successIf(str != null, "成功")
                 .orError(2333, "失败");
-        System.out.println(result);
+        log.info(result.toString());
         assertEquals(2333, result.getStatus());
         assertEquals("失败", result.getMessage());
 
         str = "";
         result = RestfulResult.successIf(str != null, "成功")
                 .orError();
-        System.out.println(result);
+        log.info(result.toString());
         assertEquals(RestfulResult.SUCCESS_STATUS, result.getStatus());
 
         result = RestfulResult.successIf(str != null, "成功", str)
                 .orError(2333, "失败");
-        System.out.println(result);
+        log.info(result.toString());
         assertEquals("成功", result.getMessage());
     }
 }