diff --git a/file-cleaner/pom.xml b/file-cleaner/pom.xml
index 84b7dfe..4991176 100644
--- a/file-cleaner/pom.xml
+++ b/file-cleaner/pom.xml
@@ -9,21 +9,39 @@
     <version>0.0.1-SNAPSHOT</version>
 
     <properties>
+        <!-- https://maven.apache.org/general.html#encoding-warning -->
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <maven.compiler.source>1.8</maven.compiler.source>
+        <maven.compiler.target>1.8</maven.compiler.target>
     </properties>
 
-
     <dependencies>
+        <!-- junit 5, unit test -->
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-engine</artifactId>
+            <version>5.7.2</version>
+            <scope>test</scope>
+        </dependency>
+
         <dependency>
             <groupId>org.apache.logging.log4j</groupId>
             <artifactId>log4j-slf4j-impl</artifactId>
-            <version>2.9.0</version>
+            <version>2.14.1</version>
         </dependency>
     </dependencies>
 
     <build>
-
         <plugins>
+
+            <!--The default maven-surefire-plugin is outdated,
+            make sure update to the latest.-->
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-surefire-plugin</artifactId>
+                <version>2.22.2</version>
+            </plugin>
+
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-shade-plugin</artifactId>
@@ -45,9 +63,11 @@
                     </execution>
                 </executions>
             </plugin>
+
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>
+                <version>3.8.1</version>
                 <configuration>
                     <source>8</source>
                     <target>8</target>
diff --git a/file-cleaner/src/main/java/de/begerad/fileagerm/FileCleaner.java b/file-cleaner/src/main/java/de/begerad/fileagerm/FileCleaner.java
index 27e3dea..d74f96c 100644
--- a/file-cleaner/src/main/java/de/begerad/fileagerm/FileCleaner.java
+++ b/file-cleaner/src/main/java/de/begerad/fileagerm/FileCleaner.java
@@ -1,38 +1,53 @@
 package de.begerad.fileagerm;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import java.io.File;
 
-import static de.begerad.fileagerm.Main.LOG;
-
 public class FileCleaner {
 
+    public final static Logger LOG = LoggerFactory.getLogger(FileCleaner.class);
+
     /**
      * Clean-up files older than a certain time
      *
      * @param age     age of files to be cleaned up
      * @param dirPath directory path of files to be cleaned up
      */
-    public static void deleteFilesByAge(int age, String dirPath) {
+    public static int deleteFilesByAge(int age, String dirPath) {
 
+        int count = 0;
+        LOG.debug("dirPath: {}", dirPath);
         File directory = new File(dirPath);
         if (directory.exists()) {
 
             File[] listFiles = FileExplorer.listFiles(dirPath);
             LOG.debug("listFiles.length: {}", listFiles.length);
-            long purgeTime = System.currentTimeMillis() - (age * 24L * 60L * 60L * 1000L);
-            for (File listFile : listFiles) {
-                if (listFile.lastModified() < purgeTime) {
-                    if (!listFile.delete()) {
-                        LOG.warn("file could NOT be deleted: {}", listFile.getName());
+            if (listFiles.length > 0) {
+                long purgeTime = System.currentTimeMillis()
+                        - (age * 24L * 60L * 60L * 1000L);
+                for (File listFile : listFiles) {
+                    if (listFile.lastModified() < purgeTime) {
+                        if (!listFile.delete()) {
+                            LOG.warn("file could NOT be deleted: {}",
+                                    listFile.getName());
+                        } else {
+                            LOG.debug("file deleted: {}",
+                                    listFile.getName());
+                            count++;
+                        }
                     } else {
-                        LOG.debug("file deleted: {}", listFile.getName());
+                        LOG.debug("file is too young to be deleted: {}",
+                                listFile.getName());
                     }
-                } else {
-                    LOG.debug("file is too young to be deleted: {}", listFile.getName());
                 }
+            } else {
+                LOG.debug("NO files present");
             }
         } else {
             LOG.warn("directory does not exist: {}", directory);
         }
+        return count;
     }
 }
diff --git a/file-cleaner/src/main/java/de/begerad/fileagerm/FileExplorer.java b/file-cleaner/src/main/java/de/begerad/fileagerm/FileExplorer.java
index c9a105d..8bb7672 100644
--- a/file-cleaner/src/main/java/de/begerad/fileagerm/FileExplorer.java
+++ b/file-cleaner/src/main/java/de/begerad/fileagerm/FileExplorer.java
@@ -2,42 +2,8 @@ package de.begerad.fileagerm;
 
 import java.io.File;
 import java.io.FileFilter;
-import java.util.Set;
-import java.util.stream.Collectors;
-import java.util.stream.Stream;
 
 public class FileExplorer {
-    private final String directory;
-
-    public FileExplorer(String directory) {
-        this.directory = directory;
-    }
-
-    /**
-     * @return set containing list of file paths
-     */
-    public Set<String> listFilesUsingJavaIO() {
-        return Stream.of(new File(directory).listFiles())
-                .filter(file -> !file.isDirectory())
-                .map(File::getName)
-                .collect(Collectors.toSet());
-    }
-
-    /**
-     * @return array containing list of File objects
-     */
-    public File[] listFilesUsingFileFilter() {
-        //Creating a File object for directory
-        File dir = new File(directory);
-        //Creating filter for directory files
-        FileFilter fileFilter = new FileFilter() {
-            public boolean accept(File dir) {
-                return dir.isFile();
-            }
-        };
-
-        return dir.listFiles(fileFilter);
-    }
 
     /**
      * @return array containing list of File objects
diff --git a/file-cleaner/src/main/java/de/begerad/fileagerm/Main.java b/file-cleaner/src/main/java/de/begerad/fileagerm/Main.java
index c2f60aa..3d5c1b0 100644
--- a/file-cleaner/src/main/java/de/begerad/fileagerm/Main.java
+++ b/file-cleaner/src/main/java/de/begerad/fileagerm/Main.java
@@ -6,7 +6,6 @@ import org.slf4j.LoggerFactory;
 import java.io.File;
 import java.io.IOException;
 import java.util.Calendar;
-import java.util.Set;
 
 import static de.begerad.fileagerm.FileCleaner.deleteFilesByAge;
 
@@ -31,39 +30,14 @@ public class Main {
                     + " is NOT a valid directory.");
             return;
         }
+
         try {
-            System.out.println("dir path: "
-                    + (new File(dirPath).getCanonicalPath()));
             LOG.debug("dir path: {}",
                     (new File(dirPath).getCanonicalPath()));
         } catch (IOException e) {
             e.printStackTrace();
         }
 
-        FileExplorer fileList = new FileExplorer(dirPath);
-        File[] list = fileList.listFilesUsingFileFilter();
-        LOG.debug("List of files in the specified directory:");
-        if (list != null) {
-            for (File file : list) {
-                LOG.debug("file name: {}", file.getName());
-                LOG.debug("file path: {}", file.getPath());
-                LOG.debug("file abs path: {}", file.getAbsolutePath());
-                try {
-                    LOG.debug("file can path: {}", file.getCanonicalPath());
-                } catch (IOException e) {
-                    e.printStackTrace();
-                }
-            }
-        } else {
-            LOG.warn("List of files is empty");
-        }
-
-        Set<String> setList = fileList.listFilesUsingJavaIO();
-        LOG.debug("List of files in the specified directory:");
-        for (String file : setList) {
-            LOG.debug("{}", file);
-        }
-
         int age = 1;
         long purgeTime = System.currentTimeMillis() - (age * 24L * 60L * 60L * 1000L);
         LOG.debug("age in ms: {}", purgeTime);
@@ -73,7 +47,8 @@ public class Main {
         purgeTime = cal.getTimeInMillis();
         LOG.debug("age in ms: {}", purgeTime);
 
-        deleteFilesByAge(age, dirPath);
+        int filesDeleted = deleteFilesByAge(age, dirPath);
+        LOG.debug("# files deleted: " + filesDeleted);
 
         LOG.debug("main() done.");
     }
diff --git a/file-cleaner/src/test/java/de/begerad/fileagerm/TestFileCleaner.java b/file-cleaner/src/test/java/de/begerad/fileagerm/TestFileCleaner.java
index ce604b5..4cc340c 100644
--- a/file-cleaner/src/test/java/de/begerad/fileagerm/TestFileCleaner.java
+++ b/file-cleaner/src/test/java/de/begerad/fileagerm/TestFileCleaner.java
@@ -1,4 +1,50 @@
 package de.begerad.fileagerm;
 
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
 public class TestFileCleaner {
+    private final static int AGE_YEAR = 365;
+    private final static int AGE_HALF_YEAR = 183;
+    private final static int AGE_ZERO = 0;
+    private final static String DIR_PATH_TMP = "/tmp";
+    private final static String DIR_PATH_VAR = "/var";
+    private final static String DIR_PATH_DOT_NPM = "/root/.npm";
+    private final static String DIR_PATH_TMP_DEL = "/tmp/del";
+
+    @Test
+    public void testZeroAge() {
+        int count = FileCleaner.deleteFilesByAge(AGE_YEAR,
+                DIR_PATH_TMP);
+        assertEquals(0, count);
+    }
+
+    @Test
+    public void testZeroFiles() {
+        int count = FileCleaner.deleteFilesByAge(AGE_YEAR,
+                DIR_PATH_VAR);
+        assertEquals(0, count);
+    }
+
+    @Test
+    public void testDirDoesNotExist() {
+        int count = FileCleaner.deleteFilesByAge(AGE_YEAR,
+                DIR_PATH_DOT_NPM);
+        assertEquals(0, count);
+    }
+
+    @Test
+    public void testRootDir() {
+        int count = FileCleaner.deleteFilesByAge(AGE_HALF_YEAR,
+                "/usr/local/share/fonts/");
+        assertEquals(0, count);
+    }
+
+    @Test
+    public void testFileDeleted() {
+        int count = FileCleaner.deleteFilesByAge(AGE_ZERO,
+                DIR_PATH_TMP_DEL);
+        assertEquals(1, count);
+    }
 }
diff --git a/file-cleaner/src/test/java/de/begerad/fileagerm/TestFileExplorer.java b/file-cleaner/src/test/java/de/begerad/fileagerm/TestFileExplorer.java
index 32cd5e9..ecefe81 100644
--- a/file-cleaner/src/test/java/de/begerad/fileagerm/TestFileExplorer.java
+++ b/file-cleaner/src/test/java/de/begerad/fileagerm/TestFileExplorer.java
@@ -11,11 +11,17 @@ public class TestFileExplorer {
     @Test
     public void testEmptyListFiles() {
         File[] files = FileExplorer.listFiles("/mnt");
-        assertTrue(files.length == 0);
+        assertEquals(0, files.length);
     }
 
     @Test
     public void testNullListFiles() {
         assertNull(FileExplorer.listFiles("/etc/hosts"));
     }
+
+    @Test
+    public void testLengthListFiles() {
+        File[] files = FileExplorer.listFiles("/var/www/test/public_html");
+        assertEquals(1, files.length);
+    }
 }