diff --git a/testable-agent/src/main/java/com/alibaba/testable/agent/transformer/TestableClassTransformer.java b/testable-agent/src/main/java/com/alibaba/testable/agent/transformer/TestableClassTransformer.java
index 0907142..9e076a1 100644
--- a/testable-agent/src/main/java/com/alibaba/testable/agent/transformer/TestableClassTransformer.java
+++ b/testable-agent/src/main/java/com/alibaba/testable/agent/transformer/TestableClassTransformer.java
@@ -16,17 +16,15 @@ import org.objectweb.asm.tree.ClassNode;
 import org.objectweb.asm.tree.InnerClassNode;
 
 import javax.lang.model.type.NullType;
-import java.io.FileOutputStream;
-import java.io.IOException;
 import java.lang.instrument.ClassFileTransformer;
 import java.security.ProtectionDomain;
 import java.util.List;
 
 import static com.alibaba.testable.agent.constant.ConstPool.KOTLIN_POSTFIX_COMPANION;
-import static com.alibaba.testable.core.constant.ConstPool.*;
 import static com.alibaba.testable.agent.util.ClassUtil.toJavaStyleClassName;
+import static com.alibaba.testable.core.constant.ConstPool.DOLLAR;
 import static com.alibaba.testable.core.constant.ConstPool.TEST_POSTFIX;
-import static org.objectweb.asm.Opcodes.*;
+import static org.objectweb.asm.Opcodes.ACC_STATIC;
 
 /**
  * @author flin
@@ -69,14 +67,14 @@ public class TestableClassTransformer implements ClassFileTransformer {
                 // it's a mock class
                 LogUtil.diagnose("Handling mock class %s", className);
                 bytes = new MockClassHandler(className).getBytes(bytes);
-                dumpByte(className, GlobalConfig.getDumpPath(), bytes);
+                BytecodeUtil.dumpByte(className, GlobalConfig.getDumpPath(), bytes);
             } else {
                 String mockClass = foundMockForTestClass(className);
                 if (mockClass != null) {
                     // it's a test class with testable enabled
                     LogUtil.diagnose("Handling test class %s", className);
                     bytes = new TestClassHandler().getBytes(bytes);
-                    dumpByte(className, GlobalConfig.getDumpPath(), bytes);
+                    BytecodeUtil.dumpByte(className, GlobalConfig.getDumpPath(), bytes);
                 } else {
                     mockClass = foundMockForSourceClass(className);
                     if (mockClass != null) {
@@ -84,7 +82,7 @@ public class TestableClassTransformer implements ClassFileTransformer {
                         List<MethodInfo> injectMethods = mockClassParser.getTestableMockMethods(mockClass);
                         LogUtil.diagnose("Handling source class %s", className);
                         bytes = new SourceClassHandler(injectMethods, mockClass).getBytes(bytes);
-                        dumpByte(className, GlobalConfig.getDumpPath(), bytes);
+                        BytecodeUtil.dumpByte(className, GlobalConfig.getDumpPath(), bytes);
                     }
                 }
             }
@@ -95,26 +93,10 @@ public class TestableClassTransformer implements ClassFileTransformer {
         } finally {
             LogUtil.resetLogLevel();
         }
-        dumpByte(className, getDumpPathByAnnotation(cn), bytes);
+        BytecodeUtil.dumpByte(className, getDumpPathByAnnotation(cn), bytes);
         return bytes;
     }
 
-    private void dumpByte(String className, String dumpPath, byte[] bytes) {
-        if (dumpPath == null) {
-            return;
-        }
-        try {
-            String dumpFile = StringUtil.joinPath(dumpPath,
-                className.replace(SLASH, DOT).replace(DOLLAR, UNDERLINE) + ".class");
-            LogUtil.verbose("Dump class: " + dumpFile);
-            FileOutputStream stream = new FileOutputStream(dumpFile);
-            stream.write(bytes);
-            stream.close();
-        } catch (IOException e) {
-            e.printStackTrace();
-        }
-    }
-
     private String foundMockForSourceClass(String className) {
         String mockClass = lookForMockWithAnnotationAsSourceClass(className);
         if (mockClass != null) {
diff --git a/testable-agent/src/main/java/com/alibaba/testable/agent/util/BytecodeUtil.java b/testable-agent/src/main/java/com/alibaba/testable/agent/util/BytecodeUtil.java
index ebe3896..5dbf1d2 100644
--- a/testable-agent/src/main/java/com/alibaba/testable/agent/util/BytecodeUtil.java
+++ b/testable-agent/src/main/java/com/alibaba/testable/agent/util/BytecodeUtil.java
@@ -1,8 +1,14 @@
 package com.alibaba.testable.agent.util;
 
+import com.alibaba.testable.core.util.LogUtil;
+
+import java.io.FileOutputStream;
+import java.io.IOException;
 import java.util.HashMap;
 import java.util.Map;
 
+import static com.alibaba.testable.core.constant.ConstPool.*;
+import static com.alibaba.testable.core.constant.ConstPool.UNDERLINE;
 import static org.objectweb.asm.Opcodes.*;
 
 /**
@@ -193,4 +199,26 @@ public class BytecodeUtil {
         access |= ACC_PUBLIC;
         return access;
     }
+
+    /**
+     * Dump byte code to specified class file
+     * @param className original class name
+     * @param dumpPath folder to store class file
+     * @param bytes original class bytes
+     */
+    public static void dumpByte(String className, String dumpPath, byte[] bytes) {
+        if (dumpPath == null) {
+            return;
+        }
+        try {
+            String dumpFile = StringUtil.joinPath(dumpPath,
+                className.replace(SLASH, DOT).replace(DOLLAR, UNDERLINE) + ".class");
+            LogUtil.verbose("Dump class: " + dumpFile);
+            FileOutputStream stream = new FileOutputStream(dumpFile);
+            stream.write(bytes);
+            stream.close();
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
 }