diff --git a/agent/src/main/java/com/alibaba/testable/agent/handler/TestClassHandler.java b/agent/src/main/java/com/alibaba/testable/agent/handler/TestClassHandler.java
index 99d26a4..aead738 100644
--- a/agent/src/main/java/com/alibaba/testable/agent/handler/TestClassHandler.java
+++ b/agent/src/main/java/com/alibaba/testable/agent/handler/TestClassHandler.java
@@ -83,10 +83,11 @@ public class TestClassHandler extends BaseClassHandler {
     private AbstractInsnNode[] replaceTestableUtilField(MethodNode mn, AbstractInsnNode[] instructions,
                                                         String fieldName, int pos) {
         InsnList insnNodes = new InsnList();
-        insnNodes.insert(new VarInsnNode(ALOAD, 0));
+        // NOTE: will insert in reversed order
         insnNodes.insert(new MethodInsnNode(INVOKESTATIC, CLASS_TESTABLE_UTIL, FIELD_TO_METHOD_MAPPING.get(fieldName),
             SIGNATURE_TESTABLE_UTIL_METHOD, false));
-        mn.instructions.insertBefore(instructions[pos], insnNodes);
+        insnNodes.insert(new VarInsnNode(ALOAD, 0));
+        mn.instructions.insert(instructions[pos], insnNodes);
         mn.instructions.remove(instructions[pos]);
         return mn.instructions.toArray();
     }
diff --git a/core/src/main/java/com/alibaba/testable/core/tool/TestableTool.java b/core/src/main/java/com/alibaba/testable/core/tool/TestableTool.java
index de3856b..126bae6 100644
--- a/core/src/main/java/com/alibaba/testable/core/tool/TestableTool.java
+++ b/core/src/main/java/com/alibaba/testable/core/tool/TestableTool.java
@@ -5,7 +5,14 @@ package com.alibaba.testable.core.tool;
  */
 public class TestableTool {
 
+    /**
+     * Name of current test case method
+     */
     public static String TEST_CASE;
+
+    /**
+     * Name of the last visited method in source class
+     */
     public static String SOURCE_METHOD;
 
 }
diff --git a/core/src/main/java/com/alibaba/testable/core/util/ResourceUtil.java b/core/src/main/java/com/alibaba/testable/core/util/ResourceUtil.java
index f265d39..9e105de 100644
--- a/core/src/main/java/com/alibaba/testable/core/util/ResourceUtil.java
+++ b/core/src/main/java/com/alibaba/testable/core/util/ResourceUtil.java
@@ -7,6 +7,10 @@ import java.io.*;
  */
 public class ResourceUtil {
 
+    /**
+     * Read content of a text file from resource folder
+     * @param filePath file to read
+     */
     public static String fetchText(String filePath) {
         InputStream in = ResourceUtil.class.getResourceAsStream("/" + filePath);
         BufferedReader reader = new BufferedReader(new InputStreamReader(in));
@@ -24,6 +28,10 @@ public class ResourceUtil {
         }
     }
 
+    /**
+     * Read content of a binary file from resource folder
+     * @param filePath file to read
+     */
     public static byte[] fetchBinary(String filePath) {
         InputStream in = ResourceUtil.class.getResourceAsStream("/" + filePath);
         if (in == null) {
diff --git a/core/src/main/java/com/alibaba/testable/core/util/StringUtil.java b/core/src/main/java/com/alibaba/testable/core/util/StringUtil.java
index cd4b093..c32ea51 100644
--- a/core/src/main/java/com/alibaba/testable/core/util/StringUtil.java
+++ b/core/src/main/java/com/alibaba/testable/core/util/StringUtil.java
@@ -7,6 +7,11 @@ import java.util.List;
  */
 public class StringUtil {
 
+    /**
+     * Join strings
+     * @param list strings to join
+     * @param conjunction connection character
+     */
     static public String join(List<String> list, String conjunction)
     {
         StringBuilder sb = new StringBuilder();
diff --git a/core/src/main/java/com/alibaba/testable/core/util/TestableUtil.java b/core/src/main/java/com/alibaba/testable/core/util/TestableUtil.java
index 91d0001..ceb4143 100644
--- a/core/src/main/java/com/alibaba/testable/core/util/TestableUtil.java
+++ b/core/src/main/java/com/alibaba/testable/core/util/TestableUtil.java
@@ -7,19 +7,27 @@ import com.alibaba.testable.core.constant.ConstPool;
  */
 public class TestableUtil {
 
+    /**
+     * Get the last visit method in source file
+     * @param testClassRef usually `this` variable of the test class
+     * @return method name
+     */
     public static String currentSourceMethodName(Object testClassRef) {
         Class<?> testClass = testClassRef.getClass();
-        StackTraceElement[] stack = getMainThread().getStackTrace();
         String testClassName = getRealClassName(testClass);
         String sourceClassName = testClassName.substring(0, testClassName.length() - ConstPool.TEST_POSTFIX.length());
-        for (int i = stack.length - 1; i >= 0; i--) {
-            if (stack[i].getClassName().equals(sourceClassName)) {
-                return stack[i].getMethodName();
-            }
+        String sourceMethod = findLastMethodFromSourceClass(sourceClassName, getMainThread().getStackTrace());
+        if (sourceMethod.isEmpty()) {
+            return findLastMethodFromSourceClass(sourceClassName, Thread.currentThread().getStackTrace());
         }
-        return "";
+        return sourceMethod;
     }
 
+    /**
+     * Get current test case method
+     * @param testClassRef usually `this` variable of the test class
+     * @return method name
+     */
     public static String currentTestCaseName(Object testClassRef) {
         Class<?> testClass = testClassRef.getClass();
         StackTraceElement[] stack = getMainThread().getStackTrace();
@@ -32,6 +40,15 @@ public class TestableUtil {
         return "";
     }
 
+    private static String findLastMethodFromSourceClass(String sourceClassName, StackTraceElement[] stack) {
+        for (StackTraceElement element : stack) {
+            if (element.getClassName().equals(sourceClassName)) {
+                return element.getMethodName();
+            }
+        }
+        return "";
+    }
+
     private static String getRealClassName(Class<?> testClass) {
         String className = testClass.getName();
         int posOfInnerClass = className.lastIndexOf('$');
@@ -44,6 +61,7 @@ public class TestableUtil {
                 return t;
             }
         }
+        // usually impossible to go here
         return Thread.currentThread();
     }
 
diff --git a/demo/java-demo/src/test/java/com/alibaba/testable/demo/DemoServiceTest.java b/demo/java-demo/src/test/java/com/alibaba/testable/demo/DemoServiceTest.java
index 2879c15..02d755e 100644
--- a/demo/java-demo/src/test/java/com/alibaba/testable/demo/DemoServiceTest.java
+++ b/demo/java-demo/src/test/java/com/alibaba/testable/demo/DemoServiceTest.java
@@ -6,6 +6,7 @@ import com.alibaba.testable.core.annotation.TestableInject;
 import org.junit.jupiter.api.Test;
 
 import java.util.concurrent.Callable;
+import java.util.concurrent.Executors;
 
 import static com.alibaba.testable.core.tool.TestableTool.SOURCE_METHOD;
 import static com.alibaba.testable.core.tool.TestableTool.TEST_CASE;
@@ -41,6 +42,9 @@ class DemoServiceTest {
 
     @TestableInject
     private String callFromDifferentMethod() {
+        if (TEST_CASE.equals("should_able_to_get_test_case_name")) {
+            return "mock_special";
+        }
         switch (SOURCE_METHOD) {
             case "callerOne": return "mock_one";
             default: return "mock_others";
@@ -81,15 +85,19 @@ class DemoServiceTest {
 
     @Test
     void should_able_to_get_source_method_name() throws Exception {
-        assertEquals("mock_one_mock_others", demoService.callerTwo() + "_" + demoService.callerOne());
-        assertEquals("mock_one_mock_others", ((Callable<String>)() ->
-            demoService.callerOne() + "_" + demoService.callerTwo()).call());
+        // synchronous
+        assertEquals("mock_one_mock_others", demoService.callerOne() + "_" + demoService.callerTwo());
+        // asynchronous
+        assertEquals("mock_one_mock_others",
+            Executors.newSingleThreadExecutor().submit(() -> demoService.callerOne() + "_" + demoService.callerTwo()).get());
     }
 
     @Test
     void should_able_to_get_test_case_name() throws Exception {
-        assertEquals("should_able_to_get_test_case_name", TEST_CASE);
-        assertEquals("should_able_to_get_test_case_name", ((Callable<String>)() -> TEST_CASE).call());
+        // synchronous
+        assertEquals("mock_special", demoService.callerOne());
+        // asynchronous
+        assertEquals("mock_special", Executors.newSingleThreadExecutor().submit(() -> demoService.callerOne()).get());
     }
 
 }
diff --git a/demo/kotlin-demo/src/test/kotlin/com/alibaba/testable/demo/DemoServiceTest.kt b/demo/kotlin-demo/src/test/kotlin/com/alibaba/testable/demo/DemoServiceTest.kt
index 7554509..854f2fb 100644
--- a/demo/kotlin-demo/src/test/kotlin/com/alibaba/testable/demo/DemoServiceTest.kt
+++ b/demo/kotlin-demo/src/test/kotlin/com/alibaba/testable/demo/DemoServiceTest.kt
@@ -7,7 +7,7 @@ import com.alibaba.testable.core.tool.TestableTool.SOURCE_METHOD
 import com.alibaba.testable.core.tool.TestableTool.TEST_CASE
 import org.junit.jupiter.api.Assertions.assertEquals
 import org.junit.jupiter.api.Test
-import java.util.concurrent.Callable
+import java.util.concurrent.Executors
 
 
 @EnableTestable
@@ -29,9 +29,15 @@ internal class DemoServiceTest {
     private fun startsWith(self: BlackBox, s: String) = false
 
     @TestableInject
-    private fun callFromDifferentMethod() = when (SOURCE_METHOD) {
-        "callerOne" -> "mock_one"
-        else -> "mock_others"
+    private fun callFromDifferentMethod(): String {
+        return if (TEST_CASE == "should_able_to_get_test_case_name") {
+            "mock_special"
+        } else {
+            when (SOURCE_METHOD) {
+                "callerOne" -> "mock_one"
+                else -> "mock_others"
+            }
+        }
     }
 
     private val demoService = DemoService()
@@ -65,15 +71,21 @@ internal class DemoServiceTest {
 
     @Test
     fun should_able_to_get_source_method_name() {
-        assertEquals("mock_one_mock_others", demoService.callerTwo() + "_" + demoService.callerOne())
-        assertEquals("mock_one_mock_others", Callable<String> {
+        // synchronous
+        assertEquals("mock_one_mock_others", demoService.callerOne() + "_" + demoService.callerTwo())
+        // asynchronous
+        assertEquals("mock_one_mock_others", Executors.newSingleThreadExecutor().submit<String> {
             demoService.callerOne() + "_" + demoService.callerTwo()
-        }.call())
+        }.get())
     }
 
     @Test
     fun should_able_to_get_test_case_name() {
-        assertEquals("should_able_to_get_test_case_name", TEST_CASE)
-        assertEquals("should_able_to_get_test_case_name", Callable<String> { TEST_CASE }.call())
+        // synchronous
+        assertEquals("mock_special", demoService.callerOne())
+        // asynchronous
+        assertEquals("mock_special", Executors.newSingleThreadExecutor().submit<String> {
+            demoService.callerOne()
+        }.get())
     }
 }