Update test class for Java 12 & 13 ...

- samples only for standard features
- markdown javadoc for JEPs
- organize classes related to Java 12 & 13
- improve code readability

Author: mperor

src/test/java/pl/mperor/lab/java/Java11.java

@@ -70,20 +70,6 @@ public void testTransferTo() throws Exception {
         }
     }
 
-    @Test
-    public void testTeeingCollector() {
-        List<String> words = List.of("one", "two", "three");
-
-        SimpleEntry<Integer, Long> pair = words.stream().collect(Collectors.teeing(
-                Collectors.summingInt(String::length),
-                Collectors.counting(),
-                SimpleEntry::new)
-        );
-
-        Assertions.assertEquals(11, pair.getKey());
-        Assertions.assertEquals(3, pair.getValue());
-    }
-
     @Test
     public void testCollectionToArray() {
         Assertions.assertArrayEquals(new String[]{"x", "y", "z"}, List.of("x", "y", "z").toArray(String[]::new));

src/test/java/pl/mperor/lab/java/Java12.java

@@ -9,11 +9,26 @@
 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
 import java.text.NumberFormat;
+import java.util.AbstractMap;
+import java.util.List;
 import java.util.Locale;
+import java.util.concurrent.CompletableFuture;
+import java.util.stream.Collectors;
 
-/**
- * Java 12 (March 2019)
- */
+/// Java 12™ (March 2019)
+/// [JDK 12](https://openjdk.org/projects/jdk/12)
+///
+/// - STANDARD FEATURES:
+///     - 230:	Microbenchmark Suite
+///     - 334:	JVM Constants API
+///     - 340:	One AArch64 Port, Not Two
+///     - 341:	Default CDS Archives (`-Xshare:dump`)
+///     - 344:	Abortable Mixed Collections for G1
+///     - 346:	Promptly Return Unused Committed Memory from G1 (`-XX:SoftMaxHeapSize`)
+///
+/// - PREVIEW & INCUBATOR:
+///     - 189:	Shenandoah: A Low-Pause-Time Garbage Collector "Experimental" (`-XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC`)
+///     - 325:	Switch Expressions (Preview)
 public class Java12 {
 
     @Test
@@ -60,4 +75,29 @@ public void testCompactNumberFormat() {
         Assertions.assertEquals("1.02M", shortNumberFormat.format(1_020_000));
     }
 
+    @Test
+    public void testTeeingCollector() {
+        List<String> words = List.of("one", "two", "three");
+
+        AbstractMap.SimpleEntry<Integer, Long> pair = words.stream().collect(Collectors.teeing(
+                Collectors.summingInt(String::length),
+                Collectors.counting(),
+                AbstractMap.SimpleEntry::new)
+        );
+
+        Assertions.assertEquals(11, pair.getKey());
+        Assertions.assertEquals(3, pair.getValue());
+    }
+
+    @Test
+    public void testCompletableExceptionallyCompose() {
+        var errorThrowingPlanA = CompletableFuture.supplyAsync(() -> 1 / 0);
+        var noErrorPlanB = CompletableFuture.supplyAsync(() -> 0);
+
+        errorThrowingPlanA.exceptionallyComposeAsync(ex -> {
+            Assertions.assertInstanceOf(ArithmeticException.class, ex);
+            return noErrorPlanB;
+        }).thenAccept(result -> Assertions.assertEquals(0, result));
+    }
+
 }

src/test/java/pl/mperor/lab/java/Java13.java

@@ -3,10 +3,27 @@
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 
-import java.util.Locale;
+import java.io.IOException;
+import java.net.ServerSocket;
 
-/**
- * Java 13 (September 2019)
- */
+/// Java 13™ (September 2019)
+/// [JDK 13](https://openjdk.org/projects/jdk/13)
+///
+/// - STANDARD FEATURES:
+///     - 353:	Reimplement the Legacy Socket API (`-Djdk.net.usePlainSocketImpl`)
+///     - 350:	Dynamic CDS (Class-Data Sharing) Archives (`-XX:ArchiveClassesAtExit=hello.jsa`)
+///     - 351:	ZGC: Uncommit Unused Memory (`-XX:+UseZGC`)
+///
+/// - PREVIEW & INCUBATOR:
+///     - 354:	Switch Expressions (Preview)
+///     - 355:	Text Blocks (Preview)
 public class Java13 {
+
+    @Test
+    public void testServerSocketImpl() throws IOException {
+        try (ServerSocket serverSocket = new ServerSocket(8013)) {
+            Assertions.assertNotNull(serverSocket);
+        }
+    }
+
 }

src/test/java/pl/mperor/lab/java/Java15.java

@@ -103,9 +103,10 @@ public void testNashornEngineRemoved() {
     }
 
     @Test
-    public void testDatagramSocket() throws SocketException {
-        DatagramSocket datagramSocket = new DatagramSocket();
-        Assertions.assertNotNull(datagramSocket);
+    public void testDatagramSocketImpl() throws SocketException {
+        try (DatagramSocket datagramSocket = new DatagramSocket(8015)) {
+            Assertions.assertNotNull(datagramSocket);
+        }
     }
 
 }

src/test/java/pl/mperor/lab/java/Java18.java

@@ -52,7 +52,7 @@ public void testDefaultCharsetIsUTF8() throws IOException {
 
     @Test
     public void testSimpleWebServer() throws IOException, InterruptedException {
-        HttpServer server = HttpServer.create(new InetSocketAddress(9000), 0);
+        HttpServer server = HttpServer.create(new InetSocketAddress(8018), 0);
         server.createContext("/hello", exchange -> {
             String response = "Hello World!";
             exchange.sendResponseHeaders(200, response.getBytes().length);
@@ -62,7 +62,7 @@ public void testSimpleWebServer() throws IOException, InterruptedException {
         });
         server.start();
         Assertions.assertNotNull(server);
-        Assertions.assertEquals("Hello World!", curlResponse("http://127.0.0.1:9000/hello"));
+        Assertions.assertEquals("Hello World!", curlResponse("http://127.0.0.1:8018/hello"));
 
         server.stop(0);
     }

src/test/java/pl/mperor/lab/java/Java4.java

@@ -92,7 +92,7 @@ public void testImageIO() throws IOException {
     }
     @Test
     public void testServerClientSocketChannel() throws IOException, InterruptedException {
-        int port = 8888;
+        int port = 8004;
         CountDownLatch serverReadyLatch = new CountDownLatch(1);
 
         var executorService = Executors.newSingleThreadExecutor();