Initial commit of code to accompany article on copying data from InputStream to OutputStream

core-java-modules/core-java-9/src/test/java/com/baeldung/java9/inputstream/outputstream/InputStreamToOutputStreamUnitTest.java

@@ -0,0 +1,85 @@
+package com.baeldung.java9.inputstream.outputstream;
+
+import static org.apache.commons.lang3.RandomStringUtils.randomAlphabetic;
+import static org.junit.Assert.assertEquals;
+
+import java.io.*;
+
+import org.apache.commons.io.IOUtils;
+import org.junit.Test;
+
+import com.google.common.io.ByteStreams;
+
+public class InputStreamToOutputStreamUnitTest {
+
+    // buffer size used for reading and writing
+    private static final int BUFFER_SIZE = 8192;
+
+    /**
+     * Reads all bytes from an input stream and writes them to an output stream.
+     * @param source - input stream to copy data from
+     * @param target - output stream to copy data too
+     */
+    private static void copy(InputStream source, OutputStream target) throws IOException {
+        byte[] buf = new byte[BUFFER_SIZE];
+        int length;
+        while ((length = source.read(buf)) > 0) {
+            target.write(buf, 0, length);
+        }
+    }
+
+    @Test
+    public final void givenUsingJavaEight_whenConvertingStringToInputStream_thenCorrect() throws IOException {
+        final String initialString = "Hello World!";
+
+        try (InputStream inputStream = new ByteArrayInputStream(initialString.getBytes());
+             ByteArrayOutputStream targetStream = new ByteArrayOutputStream()) {
+            copy(inputStream, targetStream);
+            assertEquals(initialString, new String(targetStream.toByteArray()));
+        }
+    }
+
+    @Test
+    public final void givenUsingJavaEight_whenConvertingVeryLongStringToInputStream_thenCorrect() throws IOException {
+        final String initialString = randomAlphabetic(20480);
+
+        try (InputStream inputStream = new ByteArrayInputStream(initialString.getBytes());
+             ByteArrayOutputStream targetStream = new ByteArrayOutputStream()) {
+            copy(inputStream, targetStream);
+            assertEquals(initialString, new String(targetStream.toByteArray()));
+        }
+    }
+
+    @Test
+    public final void givenUsingJavaNine_whenConvertingStringToInputStream_thenCorrect() throws IOException {
+        final String initialString = "Hello World!";
+
+        try (InputStream inputStream = new ByteArrayInputStream(initialString.getBytes());
+             ByteArrayOutputStream targetStream = new ByteArrayOutputStream()) {
+            inputStream.transferTo(targetStream);
+            assertEquals(initialString, new String(targetStream.toByteArray()));
+        }
+    }
+
+    @Test
+    public final void givenUsingGuava_whenConvertingStringToInputStream_thenCorrect() throws IOException {
+        final String initialString = "Hello World!";
+
+        try (InputStream inputStream = new ByteArrayInputStream(initialString.getBytes());
+             ByteArrayOutputStream targetStream = new ByteArrayOutputStream()) {
+            ByteStreams.copy(inputStream, targetStream);
+            assertEquals(initialString, new String(targetStream.toByteArray()));
+        }
+    }
+
+    @Test
+    public final void givenUsingCommonsIO_whenConvertingStringToInputStream_thenCorrect() throws IOException {
+        final String initialString = "Hello World!";
+
+        try (InputStream inputStream = new ByteArrayInputStream(initialString.getBytes());
+             ByteArrayOutputStream targetStream = new ByteArrayOutputStream()) {
+            IOUtils.copy(inputStream, targetStream);
+            assertEquals(initialString, new String(targetStream.toByteArray()));
+        }
+    }
+}