chore(deps): bump org.apache.hadoop:hadoop-common from 3.2.4 to 3.4.0 in /other/java/hdfs3 (#7512)

* chore(deps): bump org.apache.hadoop:hadoop-common in /other/java/hdfs3

Bumps org.apache.hadoop:hadoop-common from 3.2.4 to 3.4.0.

---
updated-dependencies:
- dependency-name: org.apache.hadoop:hadoop-common
  dependency-version: 3.4.0
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

* add java client unit tests

* Update dependency-reduced-pom.xml

* add java integration tests

* fix

* fix buffer

---------

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: chrislu <chris.lu@gmail.com>

5 files changed, 933 insertions, 10 deletions

diff --git a/other/java/hdfs3/README.md b/other/java/hdfs3/README.md
new file mode 100644
index 000000000..f1afee264
--- /dev/null
+++ b/other/java/hdfs3/README.md
@@ -0,0 +1,190 @@
+# SeaweedFS Hadoop3 Client
+
+Hadoop FileSystem implementation for SeaweedFS, compatible with Hadoop 3.x.
+
+## Building
+
+```bash
+mvn clean install
+```
+
+## Testing
+
+This project includes two types of tests:
+
+### 1. Configuration Tests (No SeaweedFS Required)
+
+These tests verify configuration handling and initialization logic without requiring a running SeaweedFS instance:
+
+```bash
+mvn test -Dtest=SeaweedFileSystemConfigTest
+```
+
+### 2. Integration Tests (Requires SeaweedFS)
+
+These tests verify actual FileSystem operations against a running SeaweedFS instance.
+
+#### Prerequisites
+
+1. Start SeaweedFS with default ports:
+   ```bash
+   # Terminal 1: Start master
+   weed master
+   
+   # Terminal 2: Start volume server
+   weed volume -mserver=localhost:9333
+   
+   # Terminal 3: Start filer
+   weed filer -master=localhost:9333
+   ```
+
+2. Verify services are running:
+   - Master: http://localhost:9333
+   - Filer HTTP: http://localhost:8888
+   - Filer gRPC: localhost:18888
+
+#### Running Integration Tests
+
+```bash
+# Enable integration tests
+export SEAWEEDFS_TEST_ENABLED=true
+
+# Run all tests
+mvn test
+
+# Run specific test
+mvn test -Dtest=SeaweedFileSystemTest
+```
+
+### Test Configuration
+
+Integration tests can be configured via environment variables or system properties:
+
+- `SEAWEEDFS_TEST_ENABLED`: Set to `true` to enable integration tests (default: false)
+- Tests use these default connection settings:
+  - Filer Host: localhost
+  - Filer HTTP Port: 8888
+  - Filer gRPC Port: 18888
+
+### Running Tests with Custom Configuration
+
+To test against a different SeaweedFS instance, modify the test code or use Hadoop configuration:
+
+```java
+conf.set("fs.seaweed.filer.host", "your-host");
+conf.setInt("fs.seaweed.filer.port", 8888);
+conf.setInt("fs.seaweed.filer.port.grpc", 18888);
+```
+
+## Test Coverage
+
+The test suite covers:
+
+- **Configuration & Initialization**
+  - URI parsing and configuration
+  - Default values
+  - Configuration overrides
+  - Working directory management
+
+- **File Operations**
+  - Create files
+  - Read files
+  - Write files
+  - Append to files
+  - Delete files
+
+- **Directory Operations**
+  - Create directories
+  - List directory contents
+  - Delete directories (recursive and non-recursive)
+
+- **Metadata Operations**
+  - Get file status
+  - Set permissions
+  - Set owner/group
+  - Rename files and directories
+
+## Usage in Hadoop
+
+1. Copy the built JAR to your Hadoop classpath:
+   ```bash
+   cp target/seaweedfs-hadoop3-client-*.jar $HADOOP_HOME/share/hadoop/common/lib/
+   ```
+
+2. Configure `core-site.xml`:
+   ```xml
+   <configuration>
+     <property>
+       <name>fs.seaweedfs.impl</name>
+       <value>seaweed.hdfs.SeaweedFileSystem</value>
+     </property>
+     <property>
+       <name>fs.seaweed.filer.host</name>
+       <value>localhost</value>
+     </property>
+     <property>
+       <name>fs.seaweed.filer.port</name>
+       <value>8888</value>
+     </property>
+     <property>
+       <name>fs.seaweed.filer.port.grpc</name>
+       <value>18888</value>
+     </property>
+   </configuration>
+   ```
+
+3. Use SeaweedFS with Hadoop commands:
+   ```bash
+   hadoop fs -ls seaweedfs://localhost:8888/
+   hadoop fs -mkdir seaweedfs://localhost:8888/test
+   hadoop fs -put local.txt seaweedfs://localhost:8888/test/
+   ```
+
+## Continuous Integration
+
+For CI environments, tests can be run in two modes:
+
+1. **Configuration Tests Only** (default, no SeaweedFS required):
+   ```bash
+   mvn test -Dtest=SeaweedFileSystemConfigTest
+   ```
+
+2. **Full Integration Tests** (requires SeaweedFS):
+   ```bash
+   # Start SeaweedFS in CI environment
+   # Then run:
+   export SEAWEEDFS_TEST_ENABLED=true
+   mvn test
+   ```
+
+## Troubleshooting
+
+### Tests are skipped
+
+If you see "Skipping test - SEAWEEDFS_TEST_ENABLED not set":
+```bash
+export SEAWEEDFS_TEST_ENABLED=true
+```
+
+### Connection refused errors
+
+Ensure SeaweedFS is running and accessible:
+```bash
+curl http://localhost:8888/
+```
+
+### gRPC errors
+
+Verify the gRPC port is accessible:
+```bash
+# Should show the port is listening
+netstat -an | grep 18888
+```
+
+## Contributing
+
+When adding new features, please include:
+1. Configuration tests (no SeaweedFS required)
+2. Integration tests (with SEAWEEDFS_TEST_ENABLED guard)
+3. Documentation updates
+
diff --git a/other/java/hdfs3/dependency-reduced-pom.xml b/other/java/hdfs3/dependency-reduced-pom.xml
index decf55a59..d3c2751a5 100644
--- a/other/java/hdfs3/dependency-reduced-pom.xml
+++ b/other/java/hdfs3/dependency-reduced-pom.xml
@@ -140,7 +140,7 @@
     <dependency>

       <groupId>org.apache.hadoop</groupId>

       <artifactId>hadoop-client</artifactId>

-      <version>3.2.4</version>

+      <version>3.4.0</version>

       <scope>provided</scope>

       <exclusions>

         <exclusion>

@@ -172,10 +172,18 @@
     <dependency>

       <groupId>org.apache.hadoop</groupId>

       <artifactId>hadoop-common</artifactId>

-      <version>3.2.4</version>

+      <version>3.4.0</version>

       <scope>provided</scope>

       <exclusions>

         <exclusion>

+          <artifactId>hadoop-shaded-protobuf_3_21</artifactId>

+          <groupId>org.apache.hadoop.thirdparty</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>hadoop-shaded-guava</artifactId>

+          <groupId>org.apache.hadoop.thirdparty</groupId>

+        </exclusion>

+        <exclusion>

           <artifactId>commons-cli</artifactId>

           <groupId>commons-cli</groupId>

         </exclusion>

@@ -200,8 +208,8 @@
           <groupId>javax.servlet</groupId>

         </exclusion>

         <exclusion>

-          <artifactId>javax.activation-api</artifactId>

-          <groupId>javax.activation</groupId>

+          <artifactId>jakarta.activation-api</artifactId>

+          <groupId>jakarta.activation</groupId>

         </exclusion>

         <exclusion>

           <artifactId>jetty-server</artifactId>

@@ -233,7 +241,11 @@
         </exclusion>

         <exclusion>

           <artifactId>jersey-json</artifactId>

-          <groupId>com.sun.jersey</groupId>

+          <groupId>com.github.pjfanning</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>jettison</artifactId>

+          <groupId>org.codehaus.jettison</groupId>

         </exclusion>

         <exclusion>

           <artifactId>jersey-server</artifactId>

@@ -288,19 +300,248 @@
           <groupId>org.apache.curator</groupId>

         </exclusion>

         <exclusion>

-          <artifactId>htrace-core4</artifactId>

-          <groupId>org.apache.htrace</groupId>

+          <artifactId>zookeeper</artifactId>

+          <groupId>org.apache.zookeeper</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>netty-handler</artifactId>

+          <groupId>io.netty</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>netty-transport-native-epoll</artifactId>

+          <groupId>io.netty</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>metrics-core</artifactId>

+          <groupId>io.dropwizard.metrics</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>commons-compress</artifactId>

+          <groupId>org.apache.commons</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>bcprov-jdk15on</artifactId>

+          <groupId>org.bouncycastle</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>kerb-core</artifactId>

+          <groupId>org.apache.kerby</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>jackson-databind</artifactId>

+          <groupId>com.fasterxml.jackson.core</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>stax2-api</artifactId>

+          <groupId>org.codehaus.woodstox</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>woodstox-core</artifactId>

+          <groupId>com.fasterxml.woodstox</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>dnsjava</artifactId>

+          <groupId>dnsjava</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>snappy-java</artifactId>

+          <groupId>org.xerial.snappy</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>hadoop-annotations</artifactId>

+          <groupId>org.apache.hadoop</groupId>

+        </exclusion>

+      </exclusions>

+    </dependency>

+    <dependency>

+      <groupId>junit</groupId>

+      <artifactId>junit</artifactId>

+      <version>4.13.1</version>

+      <scope>test</scope>

+      <exclusions>

+        <exclusion>

+          <artifactId>hamcrest-core</artifactId>

+          <groupId>org.hamcrest</groupId>

+        </exclusion>

+      </exclusions>

+    </dependency>

+    <dependency>

+      <groupId>org.mockito</groupId>

+      <artifactId>mockito-core</artifactId>

+      <version>3.12.4</version>

+      <scope>test</scope>

+      <exclusions>

+        <exclusion>

+          <artifactId>byte-buddy</artifactId>

+          <groupId>net.bytebuddy</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>byte-buddy-agent</artifactId>

+          <groupId>net.bytebuddy</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>objenesis</artifactId>

+          <groupId>org.objenesis</groupId>

+        </exclusion>

+      </exclusions>

+    </dependency>

+    <dependency>

+      <groupId>org.apache.hadoop</groupId>

+      <artifactId>hadoop-common</artifactId>

+      <version>3.4.0</version>

+      <type>test-jar</type>

+      <scope>test</scope>

+      <exclusions>

+        <exclusion>

+          <artifactId>hadoop-shaded-protobuf_3_21</artifactId>

+          <groupId>org.apache.hadoop.thirdparty</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>hadoop-shaded-guava</artifactId>

+          <groupId>org.apache.hadoop.thirdparty</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>commons-cli</artifactId>

+          <groupId>commons-cli</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>commons-math3</artifactId>

+          <groupId>org.apache.commons</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>commons-io</artifactId>

+          <groupId>commons-io</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>commons-net</artifactId>

+          <groupId>commons-net</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>commons-collections</artifactId>

+          <groupId>commons-collections</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>javax.servlet-api</artifactId>

+          <groupId>javax.servlet</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>jakarta.activation-api</artifactId>

+          <groupId>jakarta.activation</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>jetty-server</artifactId>

+          <groupId>org.eclipse.jetty</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>jetty-util</artifactId>

+          <groupId>org.eclipse.jetty</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>jetty-servlet</artifactId>

+          <groupId>org.eclipse.jetty</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>jetty-webapp</artifactId>

+          <groupId>org.eclipse.jetty</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>jsp-api</artifactId>

+          <groupId>javax.servlet.jsp</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>jersey-core</artifactId>

+          <groupId>com.sun.jersey</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>jersey-servlet</artifactId>

+          <groupId>com.sun.jersey</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>jersey-json</artifactId>

+          <groupId>com.github.pjfanning</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>jettison</artifactId>

+          <groupId>org.codehaus.jettison</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>jersey-server</artifactId>

+          <groupId>com.sun.jersey</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>reload4j</artifactId>

+          <groupId>ch.qos.reload4j</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>commons-beanutils</artifactId>

+          <groupId>commons-beanutils</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>commons-configuration2</artifactId>

+          <groupId>org.apache.commons</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>commons-lang3</artifactId>

+          <groupId>org.apache.commons</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>commons-text</artifactId>

+          <groupId>org.apache.commons</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>slf4j-reload4j</artifactId>

+          <groupId>org.slf4j</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>avro</artifactId>

+          <groupId>org.apache.avro</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>re2j</artifactId>

+          <groupId>com.google.re2j</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>hadoop-auth</artifactId>

+          <groupId>org.apache.hadoop</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>jsch</artifactId>

+          <groupId>com.jcraft</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>curator-client</artifactId>

+          <groupId>org.apache.curator</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>curator-recipes</artifactId>

+          <groupId>org.apache.curator</groupId>

         </exclusion>

         <exclusion>

           <artifactId>zookeeper</artifactId>

           <groupId>org.apache.zookeeper</groupId>

         </exclusion>

         <exclusion>

+          <artifactId>netty-handler</artifactId>

+          <groupId>io.netty</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>netty-transport-native-epoll</artifactId>

+          <groupId>io.netty</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>metrics-core</artifactId>

+          <groupId>io.dropwizard.metrics</groupId>

+        </exclusion>

+        <exclusion>

           <artifactId>commons-compress</artifactId>

           <groupId>org.apache.commons</groupId>

         </exclusion>

         <exclusion>

-          <artifactId>kerb-simplekdc</artifactId>

+          <artifactId>bcprov-jdk15on</artifactId>

+          <groupId>org.bouncycastle</groupId>

+        </exclusion>

+        <exclusion>

+          <artifactId>kerb-core</artifactId>

           <groupId>org.apache.kerby</groupId>

         </exclusion>

         <exclusion>

@@ -320,6 +561,10 @@
           <groupId>dnsjava</groupId>

         </exclusion>

         <exclusion>

+          <artifactId>snappy-java</artifactId>

+          <groupId>org.xerial.snappy</groupId>

+        </exclusion>

+        <exclusion>

           <artifactId>hadoop-annotations</artifactId>

           <groupId>org.apache.hadoop</groupId>

         </exclusion>

@@ -328,6 +573,6 @@
   </dependencies>

   <properties>

     <seaweedfs.client.version>3.80</seaweedfs.client.version>

-    <hadoop.version>3.2.4</hadoop.version>

+    <hadoop.version>3.4.0</hadoop.version>

   </properties>

 </project>

diff --git a/other/java/hdfs3/pom.xml b/other/java/hdfs3/pom.xml
index 3faba03be..061d4d700 100644
--- a/other/java/hdfs3/pom.xml
+++ b/other/java/hdfs3/pom.xml
@@ -6,7 +6,7 @@
 
     <properties>
         <seaweedfs.client.version>3.80</seaweedfs.client.version>
-        <hadoop.version>3.2.4</hadoop.version>
+        <hadoop.version>3.4.0</hadoop.version>
     </properties>
 
     <groupId>com.seaweedfs</groupId>
@@ -171,6 +171,25 @@
             <version>${hadoop.version}</version>
             <scope>provided</scope>
         </dependency>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.13.1</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.mockito</groupId>
+            <artifactId>mockito-core</artifactId>
+            <version>3.12.4</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.hadoop</groupId>
+            <artifactId>hadoop-common</artifactId>
+            <version>${hadoop.version}</version>
+            <scope>test</scope>
+            <type>test-jar</type>
+        </dependency>
     </dependencies>
 
 </project>
diff --git a/other/java/hdfs3/src/test/java/seaweed/hdfs/SeaweedFileSystemConfigTest.java b/other/java/hdfs3/src/test/java/seaweed/hdfs/SeaweedFileSystemConfigTest.java
new file mode 100644
index 000000000..bcc08b8e2
--- /dev/null
+++ b/other/java/hdfs3/src/test/java/seaweed/hdfs/SeaweedFileSystemConfigTest.java
@@ -0,0 +1,90 @@
+package seaweed.hdfs;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.Path;
+import org.junit.Before;
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+
+/**
+ * Unit tests for SeaweedFileSystem configuration that don't require a running SeaweedFS instance.
+ * 
+ * These tests verify basic properties and constants.
+ */
+public class SeaweedFileSystemConfigTest {
+
+    private SeaweedFileSystem fs;
+    private Configuration conf;
+
+    @Before
+    public void setUp() {
+        fs = new SeaweedFileSystem();
+        conf = new Configuration();
+    }
+
+    @Test
+    public void testScheme() {
+        assertEquals("seaweedfs", fs.getScheme());
+    }
+
+    @Test
+    public void testConstants() {
+        // Test that constants are defined correctly
+        assertEquals("fs.seaweed.filer.host", SeaweedFileSystem.FS_SEAWEED_FILER_HOST);
+        assertEquals("fs.seaweed.filer.port", SeaweedFileSystem.FS_SEAWEED_FILER_PORT);
+        assertEquals("fs.seaweed.filer.port.grpc", SeaweedFileSystem.FS_SEAWEED_FILER_PORT_GRPC);
+        assertEquals(8888, SeaweedFileSystem.FS_SEAWEED_DEFAULT_PORT);
+        assertEquals("fs.seaweed.buffer.size", SeaweedFileSystem.FS_SEAWEED_BUFFER_SIZE);
+        assertEquals(4 * 1024 * 1024, SeaweedFileSystem.FS_SEAWEED_DEFAULT_BUFFER_SIZE);
+        assertEquals("fs.seaweed.replication", SeaweedFileSystem.FS_SEAWEED_REPLICATION);
+        assertEquals("fs.seaweed.volume.server.access", SeaweedFileSystem.FS_SEAWEED_VOLUME_SERVER_ACCESS);
+        assertEquals("fs.seaweed.filer.cn", SeaweedFileSystem.FS_SEAWEED_FILER_CN);
+    }
+
+    @Test
+    public void testWorkingDirectoryPathOperations() {
+        // Test path operations that don't require initialization
+        Path testPath = new Path("/test/path");
+        assertTrue("Path should be absolute", testPath.isAbsolute());
+        assertEquals("/test/path", testPath.toUri().getPath());
+        
+        Path childPath = new Path(testPath, "child");
+        assertEquals("/test/path/child", childPath.toUri().getPath());
+    }
+
+    @Test
+    public void testConfigurationProperties() {
+        // Test that configuration can be set and read
+        conf.set(SeaweedFileSystem.FS_SEAWEED_FILER_HOST, "testhost");
+        assertEquals("testhost", conf.get(SeaweedFileSystem.FS_SEAWEED_FILER_HOST));
+        
+        conf.setInt(SeaweedFileSystem.FS_SEAWEED_FILER_PORT, 9999);
+        assertEquals(9999, conf.getInt(SeaweedFileSystem.FS_SEAWEED_FILER_PORT, 0));
+        
+        conf.setInt(SeaweedFileSystem.FS_SEAWEED_BUFFER_SIZE, 8 * 1024 * 1024);
+        assertEquals(8 * 1024 * 1024, conf.getInt(SeaweedFileSystem.FS_SEAWEED_BUFFER_SIZE, 0));
+        
+        conf.set(SeaweedFileSystem.FS_SEAWEED_REPLICATION, "001");
+        assertEquals("001", conf.get(SeaweedFileSystem.FS_SEAWEED_REPLICATION));
+        
+        conf.set(SeaweedFileSystem.FS_SEAWEED_VOLUME_SERVER_ACCESS, "publicUrl");
+        assertEquals("publicUrl", conf.get(SeaweedFileSystem.FS_SEAWEED_VOLUME_SERVER_ACCESS));
+        
+        conf.set(SeaweedFileSystem.FS_SEAWEED_FILER_CN, "test-cn");
+        assertEquals("test-cn", conf.get(SeaweedFileSystem.FS_SEAWEED_FILER_CN));
+    }
+
+    @Test
+    public void testDefaultBufferSize() {
+        // Test default buffer size constant
+        int expected = 4 * 1024 * 1024; // 4MB
+        assertEquals(expected, SeaweedFileSystem.FS_SEAWEED_DEFAULT_BUFFER_SIZE);
+    }
+
+    @Test
+    public void testDefaultPort() {
+        // Test default port constant
+        assertEquals(8888, SeaweedFileSystem.FS_SEAWEED_DEFAULT_PORT);
+    }
+}
diff --git a/other/java/hdfs3/src/test/java/seaweed/hdfs/SeaweedFileSystemTest.java b/other/java/hdfs3/src/test/java/seaweed/hdfs/SeaweedFileSystemTest.java
new file mode 100644
index 000000000..4ccb21a56
--- /dev/null
+++ b/other/java/hdfs3/src/test/java/seaweed/hdfs/SeaweedFileSystemTest.java
@@ -0,0 +1,379 @@
+package seaweed.hdfs;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.FSDataInputStream;
+import org.apache.hadoop.fs.FSDataOutputStream;
+import org.apache.hadoop.fs.FileStatus;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.fs.permission.FsPermission;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.io.IOException;
+import java.net.URI;
+
+import static org.junit.Assert.*;
+
+/**
+ * Unit tests for SeaweedFileSystem.
+ * 
+ * These tests verify basic FileSystem operations against a SeaweedFS backend.
+ * Note: These tests require a running SeaweedFS filer instance.
+ * 
+ * To run tests, ensure SeaweedFS is running with default ports:
+ * - Filer HTTP: 8888
+ * - Filer gRPC: 18888
+ * 
+ * Set environment variable SEAWEEDFS_TEST_ENABLED=true to enable these tests.
+ */
+public class SeaweedFileSystemTest {
+
+    private SeaweedFileSystem fs;
+    private Configuration conf;
+    private static final String TEST_ROOT = "/test-hdfs3";
+    private static final boolean TESTS_ENABLED = 
+        "true".equalsIgnoreCase(System.getenv("SEAWEEDFS_TEST_ENABLED"));
+
+    @Before
+    public void setUp() throws Exception {
+        if (!TESTS_ENABLED) {
+            return;
+        }
+        
+        conf = new Configuration();
+        conf.set("fs.seaweed.filer.host", "localhost");
+        conf.setInt("fs.seaweed.filer.port", 8888);
+        conf.setInt("fs.seaweed.filer.port.grpc", 18888);
+        
+        fs = new SeaweedFileSystem();
+        URI uri = new URI("seaweedfs://localhost:8888/");
+        fs.initialize(uri, conf);
+        
+        // Clean up any existing test directory
+        Path testPath = new Path(TEST_ROOT);
+        if (fs.exists(testPath)) {
+            fs.delete(testPath, true);
+        }
+    }
+
+    @After
+    public void tearDown() throws Exception {
+        if (!TESTS_ENABLED || fs == null) {
+            return;
+        }
+        
+        // Clean up test directory
+        Path testPath = new Path(TEST_ROOT);
+        if (fs.exists(testPath)) {
+            fs.delete(testPath, true);
+        }
+        
+        fs.close();
+    }
+
+    @Test
+    public void testInitialization() throws Exception {
+        if (!TESTS_ENABLED) {
+            System.out.println("Skipping test - SEAWEEDFS_TEST_ENABLED not set");
+            return;
+        }
+        
+        assertNotNull(fs);
+        assertEquals("seaweedfs", fs.getScheme());
+        assertNotNull(fs.getUri());
+        assertEquals("/", fs.getWorkingDirectory().toUri().getPath());
+    }
+
+    @Test
+    public void testMkdirs() throws Exception {
+        if (!TESTS_ENABLED) {
+            System.out.println("Skipping test - SEAWEEDFS_TEST_ENABLED not set");
+            return;
+        }
+        
+        Path testDir = new Path(TEST_ROOT + "/testdir");
+        assertTrue("Failed to create directory", fs.mkdirs(testDir));
+        assertTrue("Directory should exist", fs.exists(testDir));
+        
+        FileStatus status = fs.getFileStatus(testDir);
+        assertTrue("Path should be a directory", status.isDirectory());
+    }
+
+    @Test
+    public void testCreateAndReadFile() throws Exception {
+        if (!TESTS_ENABLED) {
+            System.out.println("Skipping test - SEAWEEDFS_TEST_ENABLED not set");
+            return;
+        }
+        
+        Path testFile = new Path(TEST_ROOT + "/testfile.txt");
+        String testContent = "Hello, SeaweedFS!";
+        
+        // Create and write to file
+        FSDataOutputStream out = fs.create(testFile, FsPermission.getDefault(), 
+            false, 4096, (short) 1, 4 * 1024 * 1024, null);
+        assertNotNull("Output stream should not be null", out);
+        out.write(testContent.getBytes());
+        out.close();
+        
+        // Verify file exists
+        assertTrue("File should exist", fs.exists(testFile));
+        
+        // Read and verify content
+        FSDataInputStream in = fs.open(testFile, 4096);
+        assertNotNull("Input stream should not be null", in);
+        byte[] buffer = new byte[testContent.length()];
+        int bytesRead = in.read(buffer);
+        in.close();
+        
+        assertEquals("Should read all bytes", testContent.length(), bytesRead);
+        assertEquals("Content should match", testContent, new String(buffer));
+    }
+
+    @Test
+    public void testFileStatus() throws Exception {
+        if (!TESTS_ENABLED) {
+            System.out.println("Skipping test - SEAWEEDFS_TEST_ENABLED not set");
+            return;
+        }
+        
+        Path testFile = new Path(TEST_ROOT + "/statustest.txt");
+        String content = "test content";
+        
+        FSDataOutputStream out = fs.create(testFile);
+        out.write(content.getBytes());
+        out.close();
+        
+        FileStatus status = fs.getFileStatus(testFile);
+        assertNotNull("FileStatus should not be null", status);
+        assertFalse("Should not be a directory", status.isDirectory());
+        assertTrue("Should be a file", status.isFile());
+        assertEquals("File length should match", content.length(), status.getLen());
+        assertNotNull("Path should not be null", status.getPath());
+    }
+
+    @Test
+    public void testListStatus() throws Exception {
+        if (!TESTS_ENABLED) {
+            System.out.println("Skipping test - SEAWEEDFS_TEST_ENABLED not set");
+            return;
+        }
+        
+        Path testDir = new Path(TEST_ROOT + "/listtest");
+        fs.mkdirs(testDir);
+        
+        // Create multiple files
+        for (int i = 0; i < 3; i++) {
+            Path file = new Path(testDir, "file" + i + ".txt");
+            FSDataOutputStream out = fs.create(file);
+            out.write(("content" + i).getBytes());
+            out.close();
+        }
+        
+        FileStatus[] statuses = fs.listStatus(testDir);
+        assertNotNull("List should not be null", statuses);
+        assertEquals("Should have 3 files", 3, statuses.length);
+    }
+
+    @Test
+    public void testRename() throws Exception {
+        if (!TESTS_ENABLED) {
+            System.out.println("Skipping test - SEAWEEDFS_TEST_ENABLED not set");
+            return;
+        }
+        
+        Path srcFile = new Path(TEST_ROOT + "/source.txt");
+        Path dstFile = new Path(TEST_ROOT + "/destination.txt");
+        String content = "rename test";
+        
+        // Create source file
+        FSDataOutputStream out = fs.create(srcFile);
+        out.write(content.getBytes());
+        out.close();
+        
+        assertTrue("Source file should exist", fs.exists(srcFile));
+        
+        // Rename
+        assertTrue("Rename should succeed", fs.rename(srcFile, dstFile));
+        
+        // Verify
+        assertFalse("Source file should not exist", fs.exists(srcFile));
+        assertTrue("Destination file should exist", fs.exists(dstFile));
+        
+        // Verify content preserved
+        FSDataInputStream in = fs.open(dstFile);
+        byte[] buffer = new byte[content.length()];
+        in.read(buffer);
+        in.close();
+        assertEquals("Content should be preserved", content, new String(buffer));
+    }
+
+    @Test
+    public void testDelete() throws Exception {
+        if (!TESTS_ENABLED) {
+            System.out.println("Skipping test - SEAWEEDFS_TEST_ENABLED not set");
+            return;
+        }
+        
+        Path testFile = new Path(TEST_ROOT + "/deletetest.txt");
+        
+        // Create file
+        FSDataOutputStream out = fs.create(testFile);
+        out.write("delete me".getBytes());
+        out.close();
+        
+        assertTrue("File should exist before delete", fs.exists(testFile));
+        
+        // Delete
+        assertTrue("Delete should succeed", fs.delete(testFile, false));
+        assertFalse("File should not exist after delete", fs.exists(testFile));
+    }
+
+    @Test
+    public void testDeleteDirectory() throws Exception {
+        if (!TESTS_ENABLED) {
+            System.out.println("Skipping test - SEAWEEDFS_TEST_ENABLED not set");
+            return;
+        }
+        
+        Path testDir = new Path(TEST_ROOT + "/deletedir");
+        Path testFile = new Path(testDir, "file.txt");
+        
+        // Create directory with file
+        fs.mkdirs(testDir);
+        FSDataOutputStream out = fs.create(testFile);
+        out.write("content".getBytes());
+        out.close();
+        
+        assertTrue("Directory should exist", fs.exists(testDir));
+        assertTrue("File should exist", fs.exists(testFile));
+        
+        // Recursive delete
+        assertTrue("Recursive delete should succeed", fs.delete(testDir, true));
+        assertFalse("Directory should not exist after delete", fs.exists(testDir));
+        assertFalse("File should not exist after delete", fs.exists(testFile));
+    }
+
+    @Test
+    public void testAppend() throws Exception {
+        if (!TESTS_ENABLED) {
+            System.out.println("Skipping test - SEAWEEDFS_TEST_ENABLED not set");
+            return;
+        }
+        
+        Path testFile = new Path(TEST_ROOT + "/appendtest.txt");
+        String initialContent = "initial";
+        String appendContent = " appended";
+        
+        // Create initial file
+        FSDataOutputStream out = fs.create(testFile);
+        out.write(initialContent.getBytes());
+        out.close();
+        
+        // Append
+        FSDataOutputStream appendOut = fs.append(testFile, 4096, null);
+        assertNotNull("Append stream should not be null", appendOut);
+        appendOut.write(appendContent.getBytes());
+        appendOut.close();
+        
+        // Verify combined content
+        FSDataInputStream in = fs.open(testFile);
+        byte[] buffer = new byte[initialContent.length() + appendContent.length()];
+        int bytesRead = in.read(buffer);
+        in.close();
+        
+        String expected = initialContent + appendContent;
+        assertEquals("Should read all bytes", expected.length(), bytesRead);
+        assertEquals("Content should match", expected, new String(buffer));
+    }
+
+    @Test
+    public void testSetWorkingDirectory() throws Exception {
+        if (!TESTS_ENABLED) {
+            System.out.println("Skipping test - SEAWEEDFS_TEST_ENABLED not set");
+            return;
+        }
+        
+        Path originalWd = fs.getWorkingDirectory();
+        assertEquals("Original working directory should be /", "/", originalWd.toUri().getPath());
+        
+        Path newWd = new Path(TEST_ROOT);
+        fs.mkdirs(newWd);
+        fs.setWorkingDirectory(newWd);
+        
+        Path currentWd = fs.getWorkingDirectory();
+        assertTrue("Working directory should be updated", 
+            currentWd.toUri().getPath().contains(TEST_ROOT));
+    }
+
+    @Test
+    public void testSetPermission() throws Exception {
+        if (!TESTS_ENABLED) {
+            System.out.println("Skipping test - SEAWEEDFS_TEST_ENABLED not set");
+            return;
+        }
+        
+        Path testFile = new Path(TEST_ROOT + "/permtest.txt");
+        
+        // Create file
+        FSDataOutputStream out = fs.create(testFile);
+        out.write("permission test".getBytes());
+        out.close();
+        
+        // Set permission
+        FsPermission newPerm = new FsPermission((short) 0644);
+        fs.setPermission(testFile, newPerm);
+        
+        FileStatus status = fs.getFileStatus(testFile);
+        assertNotNull("Permission should not be null", status.getPermission());
+    }
+
+    @Test
+    public void testSetOwner() throws Exception {
+        if (!TESTS_ENABLED) {
+            System.out.println("Skipping test - SEAWEEDFS_TEST_ENABLED not set");
+            return;
+        }
+        
+        Path testFile = new Path(TEST_ROOT + "/ownertest.txt");
+        
+        // Create file
+        FSDataOutputStream out = fs.create(testFile);
+        out.write("owner test".getBytes());
+        out.close();
+        
+        // Set owner - this may not fail even if not fully implemented
+        fs.setOwner(testFile, "testuser", "testgroup");
+        
+        // Just verify the call doesn't throw an exception
+        FileStatus status = fs.getFileStatus(testFile);
+        assertNotNull("FileStatus should not be null", status);
+    }
+
+    @Test
+    public void testRenameToExistingDirectory() throws Exception {
+        if (!TESTS_ENABLED) {
+            System.out.println("Skipping test - SEAWEEDFS_TEST_ENABLED not set");
+            return;
+        }
+        
+        Path srcFile = new Path(TEST_ROOT + "/movefile.txt");
+        Path dstDir = new Path(TEST_ROOT + "/movedir");
+        
+        // Create source file and destination directory
+        FSDataOutputStream out = fs.create(srcFile);
+        out.write("move test".getBytes());
+        out.close();
+        fs.mkdirs(dstDir);
+        
+        // Rename file to existing directory (should move file into directory)
+        assertTrue("Rename to directory should succeed", fs.rename(srcFile, dstDir));
+        
+        // File should be moved into the directory
+        Path expectedLocation = new Path(dstDir, srcFile.getName());
+        assertTrue("File should exist in destination directory", fs.exists(expectedLocation));
+        assertFalse("Source file should not exist", fs.exists(srcFile));
+    }
+}
+