diff --git a/testable-agent/src/main/java/com/alibaba/testable/agent/handler/BaseClassHandler.java b/testable-agent/src/main/java/com/alibaba/testable/agent/handler/BaseClassHandler.java
index d64d811..e36a198 100644
--- a/testable-agent/src/main/java/com/alibaba/testable/agent/handler/BaseClassHandler.java
+++ b/testable-agent/src/main/java/com/alibaba/testable/agent/handler/BaseClassHandler.java
@@ -1,17 +1,35 @@
 package com.alibaba.testable.agent.handler;
 
+import com.alibaba.testable.core.util.LogUtil;
 import org.objectweb.asm.ClassReader;
 import org.objectweb.asm.ClassWriter;
 import org.objectweb.asm.Opcodes;
 import org.objectweb.asm.tree.ClassNode;
+import org.objectweb.asm.tree.FieldNode;
 
 import java.io.IOException;
+import java.util.Iterator;
 
 /**
  * @author flin
  */
 abstract public class BaseClassHandler implements Opcodes {
 
+    protected static final String TESTABLE_MARK_FIELD = "__testable";
+
+    protected boolean wasTransformed(ClassNode cn) {
+        Iterator<FieldNode> iterator = cn.fields.iterator();
+        if (iterator.hasNext()) {
+            if (TESTABLE_MARK_FIELD.equals(iterator.next().name)) {
+                // avoid duplicate injection
+                LogUtil.verbose("Duplicate injection found, ignore " + cn.name);
+                return true;
+            }
+        }
+        cn.fields.add(new FieldNode(ACC_PRIVATE, TESTABLE_MARK_FIELD, "I", null, null));
+        return false;
+    }
+
     public byte[] getBytes(byte[] classFileBuffer) throws IOException {
         ClassReader cr = new ClassReader(classFileBuffer);
         ClassNode cn = new ClassNode();
diff --git a/testable-agent/src/main/java/com/alibaba/testable/agent/handler/SourceClassHandler.java b/testable-agent/src/main/java/com/alibaba/testable/agent/handler/SourceClassHandler.java
index cbe231a..64d2046 100644
--- a/testable-agent/src/main/java/com/alibaba/testable/agent/handler/SourceClassHandler.java
+++ b/testable-agent/src/main/java/com/alibaba/testable/agent/handler/SourceClassHandler.java
@@ -36,6 +36,9 @@ public class SourceClassHandler extends BaseClassHandler {
      */
     @Override
     protected void transform(ClassNode cn) {
+        if (wasTransformed(cn)) {
+            return;
+        }
         Set<MethodInfo> memberInjectMethods = new HashSet<MethodInfo>();
         Set<MethodInfo> newOperatorInjectMethods = new HashSet<MethodInfo>();
         for (MethodInfo mi : injectMethods) {
diff --git a/testable-agent/src/main/java/com/alibaba/testable/agent/handler/TestClassHandler.java b/testable-agent/src/main/java/com/alibaba/testable/agent/handler/TestClassHandler.java
index 1ef75ca..18036a6 100644
--- a/testable-agent/src/main/java/com/alibaba/testable/agent/handler/TestClassHandler.java
+++ b/testable-agent/src/main/java/com/alibaba/testable/agent/handler/TestClassHandler.java
@@ -7,7 +7,6 @@ import com.alibaba.testable.agent.util.ClassUtil;
 import com.alibaba.testable.core.util.LogUtil;
 import org.objectweb.asm.tree.*;
 
-import java.util.Iterator;
 import java.util.List;
 
 import static com.alibaba.testable.agent.util.ClassUtil.toDotSeparateFullClassName;
@@ -20,7 +19,6 @@ public class TestClassHandler extends BaseClassHandler {
     private static final String CLASS_TESTABLE_TOOL = "com/alibaba/testable/core/tool/TestableTool";
     private static final String CLASS_TESTABLE_UTIL = "com/alibaba/testable/core/util/TestableUtil";
     private static final String CLASS_INVOKE_RECORD_UTIL = "com/alibaba/testable/core/util/InvokeRecordUtil";
-    private static final String TESTABLE_MARK_FIELD = "__testable";
     private static final String FIELD_TEST_CASE = "TEST_CASE";
     private static final String FIELD_SOURCE_METHOD = "SOURCE_METHOD";
     private static final String METHOD_CURRENT_TEST_CASE_NAME = "currentTestCaseName";
@@ -40,32 +38,19 @@ public class TestClassHandler extends BaseClassHandler {
             return;
         }
         for (MethodNode mn : cn.methods) {
-            handleMockMethod(mn);
+            handleMockMethod(cn, mn);
             handleInstruction(cn, mn);
         }
     }
 
-    private boolean wasTransformed(ClassNode cn) {
-        Iterator<FieldNode> iterator = cn.fields.iterator();
-        if (iterator.hasNext()) {
-            if (TESTABLE_MARK_FIELD.equals(iterator.next().name)) {
-                // avoid duplicate injection
-                LogUtil.verbose("Duplicate injection found, ignore " + cn.name);
-                return true;
-            }
-        }
-        cn.fields.add(new FieldNode(ACC_PRIVATE, TESTABLE_MARK_FIELD, "I", null, null));
-        return false;
-    }
-
-    private void handleMockMethod(MethodNode mn) {
+    private void handleMockMethod(ClassNode cn, MethodNode mn) {
         if (isMockMethod(mn)) {
-            toPublicStatic(mn);
+            toPublicStatic(cn, mn);
             injectInvokeRecorder(mn);
         }
     }
 
-    private void toPublicStatic(MethodNode mn) {
+    private void toPublicStatic(ClassNode cn, MethodNode mn) {
         mn.access &= ~ACC_PRIVATE;
         mn.access &= ~ACC_PROTECTED;
         mn.access |= ACC_PUBLIC;
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 844d1d6..913d307 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
@@ -45,7 +45,6 @@ public class TestableClassTransformer implements ClassFileTransformer {
                             ProtectionDomain protectionDomain, byte[] classFileBuffer) {
         if (isSystemClass(className)) {
             // Ignore system class and reloaded class
-            LogUtil.verbose("Ignore class: " + (className == null ? "<lambda>" : className));
             return null;
         }
         LogUtil.verbose("Handle class: " + className);
@@ -65,8 +64,9 @@ public class TestableClassTransformer implements ClassFileTransformer {
                 dumpByte(className, bytes);
                 resetMockContext();
             }
-        } catch (IOException e) {
+        } catch (Throwable t) {
             LogUtil.warn("Failed to transform class " + className);
+            LogUtil.diagnose(t.toString());
         }
         return bytes;
     }
@@ -77,7 +77,8 @@ public class TestableClassTransformer implements ClassFileTransformer {
             return;
         }
         try {
-            String dumpFile = StringUtil.joinPath(dumpDir, className.replaceAll("/", "_") + ".class");
+            String dumpFile = StringUtil.joinPath(dumpDir, className.replaceAll("/", ".") + ".class");
+            LogUtil.verbose("Dump class: " + dumpFile);
             FileOutputStream stream = new FileOutputStream(dumpFile);
             stream.write(bytes);
             stream.close();