From e6e0c065d509357f6a04bef853ad0f52c4c9e420 Mon Sep 17 00:00:00 2001
From: Rajesh Bhojwani <rajesh.bhojwani@gmail.com>
Date: Thu, 17 Jan 2019 15:17:09 +0530
Subject: [PATCH] Added test file to demo the deletion of file content

---
 .../file/FilesClearDataManualTest.java        | 98 +++++++++++++++++++
 .../src/test/resources/fileexample.txt        |  1 +
 2 files changed, 99 insertions(+)
 create mode 100644 core-java-io/src/test/java/com/baeldung/file/FilesClearDataManualTest.java
 create mode 100644 core-java-io/src/test/resources/fileexample.txt

diff --git a/core-java-io/src/test/java/com/baeldung/file/FilesClearDataManualTest.java b/core-java-io/src/test/java/com/baeldung/file/FilesClearDataManualTest.java
new file mode 100644
index 0000000000..8a4b3a7380
--- /dev/null
+++ b/core-java-io/src/test/java/com/baeldung/file/FilesClearDataManualTest.java
@@ -0,0 +1,98 @@
+package com.baeldung.file;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.io.BufferedWriter;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.FileWriter;
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.nio.channels.FileChannel;
+import java.nio.charset.Charset;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+import java.nio.file.StandardOpenOption;
+
+import org.apache.commons.io.FileUtils;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import com.baeldung.util.StreamUtils;
+
+public class FilesClearDataManualTest {
+	
+    public static final String FILE_PATH = "src/test/resources/fileexample.txt";
+
+    @Before
+    @After
+    public void setup() throws IOException {
+        PrintWriter writer = new PrintWriter(FILE_PATH);
+        writer.print("This example shows how we can delete the file contents without deleting the file");
+        writer.close();
+    }
+    
+    @Test
+    public void givenExistingFile_whenDeleteContentUsingPrintWritter_thenEmptyFile() throws IOException {
+        PrintWriter writer = new PrintWriter(FILE_PATH);
+        writer.print("");
+        writer.close();
+        assertEquals(0, StreamUtils.getStringFromInputStream(new FileInputStream(FILE_PATH)).length());
+    }    
+
+    @Test
+    public void givenExistingFile_whenDeleteContentUsingPrintWritterWithougObject_thenEmptyFile() throws IOException {
+        new PrintWriter(FILE_PATH).close();
+        assertEquals(0, StreamUtils.getStringFromInputStream(new FileInputStream(FILE_PATH)).length());
+    }    
+
+       
+    @Test
+    public void givenExistingFile_whenDeleteContentUsingFileWriter_thenEmptyFile() throws IOException {
+        new FileWriter(FILE_PATH, false).close();
+ 
+        assertEquals(0, StreamUtils.getStringFromInputStream(new FileInputStream(FILE_PATH)).length());
+    }
+    
+    @Test
+    public void givenExistingFile_whenDeleteContentUsingFileOutputStream_thenEmptyFile() throws IOException {
+        new FileOutputStream(FILE_PATH).close();
+
+        assertEquals(0, StreamUtils.getStringFromInputStream(new FileInputStream(FILE_PATH)).length());
+    }    
+
+    @Test
+    public void givenExistingFile_whenDeleteContentUsingFileUtils_thenEmptyFile() throws IOException {
+        FileUtils.write(new File(FILE_PATH), "", Charset.defaultCharset());
+
+        assertEquals(0, StreamUtils.getStringFromInputStream(new FileInputStream(FILE_PATH)).length());
+    }    
+
+    @Test
+    public void givenExistingFile_whenDeleteContentUsingNIOFiles_thenEmptyFile() throws IOException {
+        BufferedWriter writer = Files.newBufferedWriter(Paths.get(FILE_PATH));
+        writer.write("");
+        writer.flush();
+ 
+        assertEquals(0, StreamUtils.getStringFromInputStream(new FileInputStream(FILE_PATH)).length());
+    }    
+    
+    @Test
+    public void givenExistingFile_whenDeleteContentUsingNIOFileChannel_thenEmptyFile() throws IOException {
+        FileChannel.open(Paths.get(FILE_PATH), StandardOpenOption.WRITE).truncate(0).close();
+ 
+        assertEquals(0, StreamUtils.getStringFromInputStream(new FileInputStream(FILE_PATH)).length());
+    }   
+    
+    @Test
+    public void givenExistingFile_whenDeleteContentUsingGuava_thenEmptyFile() throws IOException {
+        File file = new File(FILE_PATH);
+        byte[] empty = new byte[0];
+        com.google.common.io.Files.write(empty, file);
+        
+        assertEquals(0, StreamUtils.getStringFromInputStream(new FileInputStream(FILE_PATH)).length());
+    }    
+    
+}
diff --git a/core-java-io/src/test/resources/fileexample.txt b/core-java-io/src/test/resources/fileexample.txt
new file mode 100644
index 0000000000..ee48fdfb84
--- /dev/null
+++ b/core-java-io/src/test/resources/fileexample.txt
@@ -0,0 +1 @@
+This example shows how we can delete the file contents without deleting the file
\ No newline at end of file