minor doc change

core-java/src/test/java/org/baeldung/java/io/JavaReaderToXUnitTest.java

@@ -1,16 +1,25 @@
 package org.baeldung.java.io;
 
+import java.io.File;
+import java.io.FileReader;
+import java.io.FileWriter;
 import java.io.IOException;
 import java.io.Reader;
 import java.io.StringReader;
+import java.io.Writer;
+import java.nio.charset.Charset;
 
+import org.apache.commons.io.FileUtils;
 import org.apache.commons.io.IOUtils;
+import org.apache.commons.io.input.CharSequenceReader;
 import org.junit.Test;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import com.google.common.io.CharSink;
 import com.google.common.io.CharSource;
 import com.google.common.io.CharStreams;
+import com.google.common.io.FileWriteMode;
 
 @SuppressWarnings("unused")
 public class JavaReaderToXUnitTest {
@@ -43,4 +52,44 @@ public class JavaReaderToXUnitTest {
         initialReader.close();
     }
 
+    // tests - Reader WRITE TO File
+
+    @Test
+    public void givenUsingPlainJava_whenConvertingReaderIntoFile_thenCorrect() throws IOException {
+        final File sourceFile = new File("src/test/resources/sourceFile.txt");
+        sourceFile.createNewFile();
+
+        final Reader initialReader = new FileReader(sourceFile);
+        final char[] buffer = new char[(int) sourceFile.length()];
+        initialReader.read(buffer);
+        initialReader.close();
+
+        final File targetFile = new File("src/test/resources/targetFile.txt");
+        targetFile.createNewFile();
+
+        final Writer targetFileWriter = new FileWriter(targetFile);
+        targetFileWriter.write(buffer);
+        targetFileWriter.close();
+    }
+
+    @Test
+    public void givenUsingGuava_whenConvertingReaderIntoFile_thenCorrect() throws IOException {
+        final Reader initialReader = CharSource.wrap("IDDQD").openStream();
+        final File targetFile = new File("src/test/resources/targetFile.txt");
+        com.google.common.io.Files.touch(targetFile);
+        final CharSink charSink = com.google.common.io.Files.asCharSink(targetFile, Charset.defaultCharset(), FileWriteMode.APPEND);
+        charSink.writeFrom(initialReader);
+        initialReader.close();
+    }
+
+    @Test
+    public void givenUsingCommonsIO_whenConvertingReaderIntoFile_thenCorrect() throws IOException {
+        final Reader initialReader = new CharSequenceReader("CharSequenceReader extends Reader");
+        final File targetFile = new File("src/test/resources/targetFile.txt");
+        FileUtils.touch(targetFile);
+        final byte[] buffer = IOUtils.toByteArray(initialReader);
+        FileUtils.writeByteArrayToFile(targetFile, buffer);
+        initialReader.close();
+    }
+
 }