BAEL-2059

* New section in InputStream to byte array article and recreating branch.

* Minor typo

* Code reformat using intellij formatter.

* Code reformat using intellij formatter.

* guava implementation to be completed

* guava implementation

* Added assert to guava test

* Fix formatting

Author: eaudet

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

@@ -0,0 +1,60 @@
+package org.baeldung.java.io;
+
+
+import com.google.common.io.ByteStreams;
+import org.apache.commons.io.IOUtils;
+import org.junit.jupiter.api.Test;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.channels.ReadableByteChannel;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class InputStreamToByteBufferUnitTest {
+
+    @Test
+    public void givenUsingCoreClasses_whenWritingAFileIntoAByteBuffer_thenBytesLengthMustMatch() throws IOException {
+        File inputFile = getFile();
+        ByteBuffer bufferByte = ByteBuffer.allocate((int) inputFile.length());
+        FileInputStream in = new FileInputStream(inputFile);
+        in.getChannel().read(bufferByte);
+
+        assertEquals(bufferByte.position(), inputFile.length());
+    }
+
+    @Test
+    public void givenUsingCommonsIo_whenWritingAFileIntoAByteBuffer_thenBytesLengthMustMatch() throws IOException {
+        File inputFile = getFile();
+        ByteBuffer bufferByte = ByteBuffer.allocateDirect((int) inputFile.length());
+        ReadableByteChannel readableByteChannel = new FileInputStream(inputFile).getChannel();
+        IOUtils.readFully(readableByteChannel, bufferByte);
+
+        assertEquals(bufferByte.position(), inputFile.length());
+    }
+
+    @Test
+    public void givenUsingGuava_whenWritingAFileIntoAByteBuffer_thenBytesLengthMustMatch() throws IOException {
+        File inputFile = getFile();
+        FileInputStream in = new FileInputStream(inputFile);
+        byte[] targetArray = ByteStreams.toByteArray(in);
+        ByteBuffer bufferByte = ByteBuffer.wrap(targetArray);
+        bufferByte.rewind();
+        while (bufferByte.hasRemaining()) {
+            bufferByte.get();
+        }
+        
+        assertEquals(bufferByte.position(), inputFile.length());
+    }
+
+    private File getFile() {
+        ClassLoader classLoader = new InputStreamToByteBufferUnitTest().getClass().getClassLoader();
+
+        String fileName = "frontenac-2257154_960_720.jpg";
+
+        return new File(classLoader.getResource(fileName).getFile());
+    }
+
+}

core-java-io/src/test/resources/frontenac-2257154_960_720.jpg

@@ -24,7 +24,7 @@
     </dependencies>
 
     <properties>
-        <guava.version>22.0</guava.version>
+        <guava.version>23.0</guava.version>
     </properties>
 
-</project>
+</project>