클래스명을 좀더 행위에 맞는 이름으로 수정.

src/main/java/sangpire/findup/Main.java

@@ -5,7 +5,7 @@
 public class Main {
   public static void main(String[] args) {
     File rootDir = new File("D:\\");
-    Worker worker = new Worker(rootDir);
-    worker.cleanUp();
+    Travler travler = new Travler();
+    travler.visit(rootDir);
   }
 }

src/main/java/sangpire/findup/Worker.java → src/main/java/sangpire/findup/Travler.java

@@ -4,21 +4,15 @@
 import java.util.Collections;
 
 /**
- * 주석 추가.
+ * 파일을 모조리 찾아내는 폴더 여행자.
  */
-public class Worker {
+public class Travler {
 
-    File rootDir;
-
-    public Worker(File rootDir) {
-        this.rootDir = rootDir;
-    }
-
-    public void cleanUp() {
-        lookupDir(0, this.rootDir);
+    public void visit(File dir) {
+        visit(0, dir);
     }
 
-    void lookupDir(Integer depth, File dir) {
+    void visit(Integer depth, File dir) {
         if (depth > 1) {
             return;
         }
@@ -34,7 +28,7 @@ void lookupDir(Integer depth, File dir) {
             String fileMetaInfos =String.format("%s%s - %s\n", margin, file.isDirectory() ? "d" : "-" ,  file.getAbsolutePath());
             System.out.print(fileMetaInfos);
             if (file.exists() && file.isDirectory()) {
-                lookupDir(depth + 1, file);
+                visit(depth + 1, file);
             }
         }
     }

src/test/java/sangpire/findup/TravlerTest.java

@@ -0,0 +1,26 @@
+package sangpire.findup;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.io.File;
+
+public class TravlerTest {
+
+    @Before
+    public void setUp() throws Exception {
+    }
+
+    @After
+    public void tearDown() throws Exception {
+    }
+
+    @Test
+    public void lookupDir() throws Exception {
+        File rootDir = new File("D:\\");
+        Travler travler = new Travler();
+        travler.visit(rootDir);
+    }
+
+}