Refactoring Java tests: 1-17

- Refactor Java 6 tests: improve dynamic compilation and add assertions for class accessibility
- Adjust wait time in Java 5 concurrency test
- Correct file path in Java 17 deserialization test
- Remove redundant whitespace in Java 4 file read test
- Refactor functional interface declaration in Java 8 tests

Author: mperor

JavaReleases/src/test/java/pl/mperor/lab/java/Java1.java

@@ -55,7 +55,7 @@ public void testJavaBean() throws IOException, ClassNotFoundException {
     }
 
     private void assertJavaBeanSerializationAndDeserialization(JavaBean bean) throws IOException, ClassNotFoundException {
-        var file = new File("src/test/resources/bean");
+        var file = new File("src/test/resources/bean.bin");
         try (ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream(file))) {
             out.writeObject(bean);
         }
@@ -107,13 +107,13 @@ public void testRemoteMethodInvocationAkaRMI() throws RemoteException, NotBoundE
         HelloService stub = (HelloService) registry.lookup("HelloService");
 
         // Call the remote method and verify the result
-        Assertions.assertEquals("Hello World!", stub.sayHello());
+        Assertions.assertEquals("Hello World!", stub.getMessage());
 
         executor.shutdown();
     }
 
     interface HelloService extends Remote {
-        String sayHello() throws RemoteException;
+        String getMessage() throws RemoteException;
     }
 
     static class HelloServiceImpl extends UnicastRemoteObject implements HelloService {
@@ -122,7 +122,7 @@ protected HelloServiceImpl() throws RemoteException {
         }
 
         @Override
-        public String sayHello() throws RemoteException {
+        public String getMessage() throws RemoteException {
             return "Hello World!";
         }
     }

JavaReleases/src/test/java/pl/mperor/lab/java/Java17.java

@@ -146,7 +146,7 @@ public void testRmiActivationRemoved() {
 
     @Test
     public void testDeserializationFilters() throws IOException, ClassNotFoundException {
-        var file = new File("src/test/resources/bean");
+        var file = new File("src/test/resources/bean.bin");
 
         var basePackageFilter = ObjectInputFilter.Config.createFilter("java.base/*;!*");
         try (ObjectInputStream in = new ObjectInputStream(new FileInputStream(file))) {

JavaReleases/src/test/java/pl/mperor/lab/java/Java3.java

@@ -27,14 +27,14 @@ public void testJavaNamingAndDirectoryInterfaceAkaJNDILookup() throws NamingExce
         String bindingName = "hello";
         String bindingResult = "Hello World!";
 
-        Context context = new InitialContext();
-        context.bind(bindingName, bindingResult);
-        String lookupResult = (String) context.lookup(bindingName);
+        Context ctx = new InitialContext();
+        ctx.bind(bindingName, bindingResult);
+        String lookupResult = (String) ctx.lookup(bindingName);
         Assertions.assertEquals(bindingResult, lookupResult);
 
-        context.unbind(bindingName);
+        ctx.unbind(bindingName);
         Assertions.assertThrows(NamingException.class, () -> {
-            context.lookup(bindingName);
+            ctx.lookup(bindingName);
         });
     }
 

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

@@ -12,7 +12,6 @@
 import java.nio.channels.SocketChannel;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.nio.file.Paths;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.Executors;
 import java.util.logging.Logger;
@@ -35,21 +34,22 @@ public void testAssertionKeyWord() {
 
     @Test
     public void testNewInputOutputAkaNIO() throws IOException {
-        Path path = Paths.get("src", "test", "resources", "nio.txt");
+        Path path = Path.of("src", "test", "resources", "nio.txt");
         byte[] fileBytes = Files.readAllBytes(path);
         String content = new String(fileBytes);
+
         Assertions.assertEquals("Hello NIO!", content);
     }
 
     @Test
     public void testRegex() {
         Pattern pattern = Pattern.compile("<title>(.*)</title>", Pattern.DOTALL);
-        Matcher matcher = pattern.matcher(getTestHtml());
+        Matcher matcher = pattern.matcher(createTestHtml());
         Assertions.assertTrue(matcher.find());
         Assertions.assertEquals("Title", matcher.group(1));
     }
 
-    private String getTestHtml() {
+    private String createTestHtml() {
         return """
                 <!DOCTYPE html>
                     <html lang="en">
@@ -89,6 +89,7 @@ public void testImageIO() throws IOException {
         BufferedImage image = ImageIO.read(new File("src/test/resources/imageio.png"));
         Assertions.assertTrue(ImageIO.write(image, "jpg", File.createTempFile("imageio", ".jpg")));
     }
+
     @Test
     public void testServerClientSocketChannel() throws IOException, InterruptedException {
         int port = 8004;
@@ -124,5 +125,4 @@ private void handleConnectedClient(ServerSocket serverSocket) throws IOException
         }
     }
 
-
 }

JavaReleases/src/test/java/pl/mperor/lab/java/Java5.java

@@ -31,7 +31,7 @@ public void testGenerics() {
         Box rawBox = new Box();
         rawBox.setContent("Hello").setContent(1);
         Assertions.assertThrows(ClassCastException.class, () -> {
-            String rawBoxContent = (String) rawBox.getContent();
+            String wrongTypeContent = (String) rawBox.getContent();
         });
         Integer rawBoxContent = (Integer) rawBox.getContent();
         Assertions.assertEquals(1, rawBoxContent);
@@ -124,7 +124,7 @@ public void testScheduledExecutor() throws InterruptedException {
             latch.countDown();
         }, 0, 100, TimeUnit.MILLISECONDS);
 
-        boolean completed = latch.await(300, TimeUnit.MILLISECONDS);
+        boolean completed = latch.await(200, TimeUnit.MILLISECONDS);
         Assertions.assertTrue(completed, "Task did not execute twice in time");
         Assertions.assertEquals(2, counter.get());
 

JavaReleases/src/test/java/pl/mperor/lab/java/Java6.java

@@ -2,6 +2,7 @@
 
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
+import pl.mperor.lab.common.TestUtils;
 
 import javax.script.ScriptEngine;
 import javax.script.ScriptEngineManager;
@@ -11,6 +12,10 @@
 import java.awt.*;
 import java.io.File;
 import java.io.IOException;
+import java.lang.reflect.InvocationTargetException;
+import java.net.MalformedURLException;
+import java.net.URL;
+import java.net.URLClassLoader;
 import java.nio.file.Files;
 
 /**
@@ -32,24 +37,36 @@ public void testScriptingLanguageSupport() throws ScriptException {
     }
 
     @Test
-    public void testJavaDynamicCompilation() throws IOException {
-        File sourceFile = new File("./HelloWorld.java");
+    public void testJavaDynamicCompilation() throws IOException, ClassNotFoundException, InvocationTargetException, NoSuchMethodException, InstantiationException, IllegalAccessException {
+        File sourceFile = new File("HelloWorld.java");
         String javaSourceCode = """
                 public class HelloWorld {
-                    public static void main(String[] args) {
-                        System.out.println("Hello World!");
+                    public void sayHello() {
+                        System.out.print("Hello World!");
                     }
                 }
                 """;
         Files.write(sourceFile.toPath(), javaSourceCode.getBytes());
 
         JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
         Assertions.assertNotNull(compiler, "JavaCompiler should not be null");
-
         int compilationResult = compiler.run(null, null, null, sourceFile.getAbsolutePath());
         Assertions.assertEquals(0, compilationResult, "Compilation should succeed with result 0!");
+        assertHelloWorldClassAccessible();
+
         Assertions.assertTrue(sourceFile.delete(), "Source file should be deleted after compilation");
-        Assertions.assertTrue(new File("./HelloWorld.class").delete(), "Now compilation result can be deleted!");
+        Assertions.assertTrue(new File("HelloWorld.class").delete(), "Now compilation result can be deleted!");
+    }
+
+    private void assertHelloWorldClassAccessible() throws MalformedURLException, ClassNotFoundException, NoSuchMethodException, InvocationTargetException, InstantiationException, IllegalAccessException {
+        URL[] urls = {new File("").toURI().toURL()};
+        URLClassLoader loader = new URLClassLoader(urls);
+        Class<?> clazz = loader.loadClass("HelloWorld");
+        Object instance = clazz.getDeclaredConstructor().newInstance();
+        var readableOut = TestUtils.setTempSystemOut();
+        clazz.getDeclaredMethod("sayHello").invoke(instance);
+        Assertions.assertEquals(readableOut.all(), "Hello World!");
+        TestUtils.resetSystemOut();
     }
 
     @Test

JavaReleases/src/test/java/pl/mperor/lab/java/Java8.java

@@ -72,6 +72,11 @@ public void testCustomFunctionalInterface() {
         assertFunctionalInterface(Testable.class);
     }
 
+    @FunctionalInterface
+    public interface Testable {
+        void test();
+    }
+
     private static void assertFunctionalInterface(Class<?> clazz) {
         if (!clazz.isInterface()) {
             Assertions.fail("Clazz is not an interface!");
@@ -86,11 +91,6 @@ private static void assertFunctionalInterface(Class<?> clazz) {
                 "Functional interface should contain exactly one abstract method, but @FunctionalInterface is optional!");
     }
 
-    @FunctionalInterface
-    public interface Testable {
-        void test();
-    }
-
     @Test
     public void testDefaultAndStaticMethodsInInterface() throws NoSuchMethodException {
         Tester tester = () -> new Testable[]{