Update Java test classes ...

- refactoring,
- extend sealed test,
- amend smart casting

Author: mperor

src/main/java/pl/mperor/lab/java/sealed/Sealed.java

@@ -1,6 +1,6 @@
 package pl.mperor.lab.java.sealed;
 
-public sealed interface Sealed permits AlsoSealed, NonSealed, Final {
+public sealed interface Sealed permits AlsoSealed, Final, NonSealed {
 
     default String sealedMethod() {
         return "sealed";

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

@@ -35,12 +35,18 @@ private String getTypeOfDayByNumber(Integer dayOfWeek) {
     }
 
     @Test
-    public void testPatternMatchingInstanceOf() {
+    public void testPatternMatchingInstanceOfAkaSmartCasting() {
         Object o = "Hello String!";
         if (o instanceof String s) {
             Assertions.assertNotNull(s);
             Assertions.assertInstanceOf(String.class, s);
         }
+        Assertions.assertTrue(nonEmptyString("Hello World!"));
+        Assertions.assertFalse(nonEmptyString(null));
+    }
+
+    private static boolean nonEmptyString(Object obj) {
+        return (obj instanceof String str) && !str.isEmpty();
     }
 
     @Test

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

@@ -10,7 +10,7 @@
 public class Java15 {
 
     @Test
-    public void testSealedClasses() {
+    public void testSealedClassesAndInterfaces() {
         Assertions.assertTrue(Sealed.class.isSealed());
         Assertions.assertFalse(NonSealed.class.isSealed());
         Assertions.assertFalse(Final.class.isSealed());
@@ -20,14 +20,35 @@ public void testSealedClasses() {
         Assertions.assertEquals("final", switchSealed(new Final()));
         Assertions.assertEquals("non-sealed", switchSealed(new NonSealed()));
         Assertions.assertEquals("sealed", switchSealed(new AlsoSealed()));
+
+        SealedClient client = new SealedClient(new NonSealedChild());
+        Assertions.assertEquals("non-sealed", client.call());
     }
 
-    private String switchSealed(Sealed sealed) {
+    private static String switchSealed(Sealed sealed) {
         return switch (sealed) {
             case AlsoSealed a -> a.alsoSealedMethod();
             case Final f -> f.finalMethod();
             case NonSealed ns -> ns.nonSealedMethod();
         };
     }
 
+    private static class NonSealedChild extends NonSealed {
+    }
+
+    // not permitted
+    // private static class SealedChild implements Sealed {
+    // }
+    public static class SealedClient {
+        private Sealed s;
+
+        public SealedClient(Sealed s) {
+            this.s = s;
+        }
+
+        public String call() {
+            return switchSealed(s);
+        }
+    }
+
 }

src/test/java/pl/mperor/lab/java/Java16.java

@@ -3,8 +3,6 @@
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
-import org.junit.jupiter.api.condition.DisabledIf;
-import org.junit.jupiter.api.condition.EnabledIfSystemProperty;
 import pl.mperor.lab.TestUtils;
 
 import java.io.IOException;