Update test classes for Java 4-17

- 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/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/Java4.java

@@ -37,6 +37,7 @@ public void testNewInputOutputAkaNIO() throws IOException {
         Path path = Path.of("src", "test", "resources", "nio.txt");
         byte[] fileBytes = Files.readAllBytes(path);
         String content = new String(fileBytes);
+
         Assertions.assertEquals("Hello NIO!", content);
     }
 

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

@@ -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[]{