Add test for validating a resolved Class before initialization

Signed-off-by: farkhalit rida <farkhlait@sproutxp.com>

Author: farkhalit

src/test/java/org/apache/commons/cli/ConverterTests.java

@@ -58,9 +58,24 @@ public AClassWithoutADefaultConstructor(final int i) {
         }
     }
 
+    // Marker type a caller might validate a resolved Class against before touching it.
+    public interface Plugin {
+    }
+
+    // A Plugin whose static initializer has an observable side effect.
+    public static class PluginImpl implements Plugin {
+
+        static {
+            pluginInitializerRan = true;
+        }
+    }
+
     // Set by the static initializer of AClassWithAStaticInitializer; readable without initializing that class.
     private static boolean classInitializerRan;
 
+    // Set by the static initializer of PluginImpl; readable without initializing that class.
+    private static boolean pluginInitializerRan;
+
     private static Stream<Arguments> numberTestParameters() {
         final List<Arguments> lst = new ArrayList<>();
         lst.add(Arguments.of("123", Long.valueOf("123")));
@@ -94,6 +109,18 @@ void testClassDoesNotInitialize() throws Exception {
         assertTrue(classInitializerRan);
     }
 
+    @Test
+    void testClassValidatedBeforeInitialization() throws Exception {
+        // The caller pattern this enables: resolve the option, gate it with isAssignableFrom, then instantiate.
+        // The assignability check must not run the class's static initializer; only newInstance() should.
+        final Class<?> cls = Converter.CLASS.apply(PluginImpl.class.getName());
+        assertTrue(Plugin.class.isAssignableFrom(cls));
+        assertFalse(pluginInitializerRan);
+        final Object instance = cls.getConstructor().newInstance();
+        assertTrue(instance instanceof Plugin);
+        assertTrue(pluginInitializerRan);
+    }
+
     @Test
     void testDate() throws Exception {
         assertThrows(java.text.ParseException.class, () -> Converter.DATE.apply("whatever"));