BAEL-4010 Add test for InputStream.readAllBytes() (#9265)

* BAEL-4010 Add test for InputStream.readAllBytes()

* BAEL-4010 Refactor: Move "InputStream to Bytes" to Java 9 specific module

The issue BAEL-4010 introduces a new example to the article "Java
InputStream to Byte Array and ByteBuffer". The example is about
  byte[] InputStream.readAllBytes()
which was added with Java 9.

To be consistent, all examples for this article were moved to a module
which is compiled with at least Java 9.

core-java-modules/core-java-9-improvements/README.md

@@ -9,3 +9,4 @@ This module contains articles about the improvements to core Java features intro
 - [Java 9 Stream API Improvements](https://www.baeldung.com/java-9-stream-api)
 - [Java 9 java.util.Objects Additions](https://www.baeldung.com/java-9-objects-new)
 - [Java 9 CompletableFuture API Improvements](https://www.baeldung.com/java-9-completablefuture)
+- [Java InputStream to Byte Array and ByteBuffer](https://www.baeldung.com/convert-input-stream-to-array-of-bytes)

core-java-modules/core-java-9-improvements/pom.xml

@@ -33,6 +33,11 @@
             <artifactId>guava</artifactId>
             <version>${guava.version}</version>
         </dependency>
+        <dependency>
+            <groupId>commons-io</groupId>
+            <artifactId>commons-io</artifactId>
+            <version>${commons-io.version}</version>
+        </dependency>
         <dependency>
             <groupId>org.junit.platform</groupId>
             <artifactId>junit-platform-runner</artifactId>

core-java-modules/core-java-9-improvements/src/test/java/com/baeldung/java9/io/conversion/InputStreamToByteArrayUnitTest.java

@@ -0,0 +1,57 @@
+package com.baeldung.java9.io.conversion;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+
+import org.apache.commons.io.IOUtils;
+import org.junit.Test;
+
+import com.google.common.io.ByteSource;
+import com.google.common.io.ByteStreams;
+
+public class InputStreamToByteArrayUnitTest {
+
+    @Test
+    public final void givenUsingPlainJavaOnFixedSizeStream_whenConvertingAnInputStreamToAByteArray_thenCorrect() throws IOException {
+        final InputStream initialStream = new ByteArrayInputStream(new byte[] { 0, 1, 2 });
+        final byte[] targetArray = new byte[initialStream.available()];
+        initialStream.read(targetArray);
+    }
+
+    @Test
+    public final void givenUsingPlainJavaOnUnknownSizeStream_whenConvertingAnInputStreamToAByteArray_thenCorrect() throws IOException {
+        final InputStream is = new ByteArrayInputStream(new byte[] { 0, 1, 2 });
+
+        final ByteArrayOutputStream buffer = new ByteArrayOutputStream();
+        int nRead;
+        final byte[] data = new byte[1024];
+        while ((nRead = is.read(data, 0, data.length)) != -1) {
+            buffer.write(data, 0, nRead);
+        }
+
+        buffer.flush();
+        final byte[] byteArray = buffer.toByteArray();
+    }
+
+    @Test
+    public void givenUsingPlainJava9_whenConvertingAnInputStreamToAByteArray_thenCorrect() throws IOException {
+        final InputStream is = new ByteArrayInputStream(new byte[] { 0, 1, 2 });
+
+        byte[] data = is.readAllBytes();
+    }
+
+    @Test
+    public final void givenUsingGuava_whenConvertingAnInputStreamToAByteArray_thenCorrect() throws IOException {
+        final InputStream initialStream = ByteSource.wrap(new byte[] { 0, 1, 2 })
+            .openStream();
+        final byte[] targetArray = ByteStreams.toByteArray(initialStream);
+    }
+
+    @Test
+    public final void givenUsingCommonsIO_whenConvertingAnInputStreamToAByteArray_thenCorrect() throws IOException {
+        final InputStream initialStream = new ByteArrayInputStream(new byte[] { 0, 1, 2 });
+        final byte[] targetArray = IOUtils.toByteArray(initialStream);
+    }
+}

core-java-modules/core-java-9-improvements/src/test/java/com/baeldung/java9/io/conversion/InputStreamToByteBufferUnitTest.java

@@ -0,0 +1,56 @@
+package com.baeldung.java9.io.conversion;
+
+import com.google.common.io.ByteSource;
+import com.google.common.io.ByteStreams;
+import org.apache.commons.io.IOUtils;
+import org.junit.Test;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.ByteBuffer;
+import java.nio.channels.ReadableByteChannel;
+
+import static java.nio.channels.Channels.newChannel;
+import static org.junit.Assert.assertEquals;
+
+public class InputStreamToByteBufferUnitTest {
+
+    @Test
+    public void givenUsingCoreClasses_whenByteArrayInputStreamToAByteBuffer_thenLengthMustMatch() throws IOException {
+        byte[] input = new byte[] { 0, 1, 2 };
+        InputStream initialStream = new ByteArrayInputStream(input);
+        ByteBuffer byteBuffer = ByteBuffer.allocate(3);
+        while (initialStream.available() > 0) {
+            byteBuffer.put((byte) initialStream.read());
+        }
+
+        assertEquals(byteBuffer.position(), input.length);
+    }
+
+    @Test
+    public void givenUsingGuava__whenByteArrayInputStreamToAByteBuffer_thenLengthMustMatch() throws IOException {
+        InputStream initialStream = ByteSource
+          .wrap(new byte[] { 0, 1, 2 })
+          .openStream();
+        byte[] targetArray = ByteStreams.toByteArray(initialStream);
+        ByteBuffer bufferByte = ByteBuffer.wrap(targetArray);
+        while (bufferByte.hasRemaining()) {
+            bufferByte.get();
+        }
+
+        assertEquals(bufferByte.position(), targetArray.length);
+    }
+
+    @Test
+    public void givenUsingCommonsIo_whenByteArrayInputStreamToAByteBuffer_thenLengthMustMatch() throws IOException {
+        byte[] input = new byte[] { 0, 1, 2 };
+        InputStream initialStream = new ByteArrayInputStream(input);
+        ByteBuffer byteBuffer = ByteBuffer.allocate(3);
+        ReadableByteChannel channel = newChannel(initialStream);
+        IOUtils.readFully(channel, byteBuffer);
+
+        assertEquals(byteBuffer.position(), input.length);
+    }
+
+}