Add basic tests for Java 20, deactivate Java 19 preview tests

Signed-off-by: Alexander Kriegisch <Alexander@Kriegisch.name>

2 files changed, 184 insertions, 0 deletions

diff --git a/tests/features1920/java20/SwitchPatternPreview4Error.java b/tests/features1920/java20/SwitchPatternPreview4Error.java
new file mode 100644
index 000000000..a682c15c4
--- /dev/null
+++ b/tests/features1920/java20/SwitchPatternPreview4Error.java
@@ -0,0 +1,37 @@
+/**
+ * This used to work up to preview 3 (Java 19), but no longer in preview 4 (Java 20).
+ * Now, the default case seems to need to be the last one in the list.
+ *
+ * Javac says 4x: "this case label is dominated by a preceding case label"
+ *
+ * ECJ/AJC says 11x: "This case label is dominated by one of the preceding case label" (yes, "label" singular)
+ * See https://github.com/eclipse-jdt/eclipse.jdt.core/issues/919.
+ */
+public class SwitchPatternPreview4Error {
+  static void defaultCanAppearBeforePattern(Integer i) {
+    switch (i) {
+      case null -> System.out.println("value unavailable: " + i);
+      case -1, 1 -> System.out.println("absolute value 1: " + i);
+      default -> System.out.println("other integer: " + i);
+      case Integer value when value > 0 -> System.out.println("positive integer: " + i);
+    }
+  }
+
+  static void defaultCanAppearBeforeNull(Integer i) {
+    switch (i) {
+      case -1, 1 -> System.out.println("absolute value 1: " + i);
+      default -> System.out.println("other integer: " + i);
+      case null -> System.out.println("value unavailable: " + i);
+      case Integer value when value > 0 -> System.out.println("positive integer: " + i);
+    }
+  }
+
+  static void defaultCanAppearBeforeConstantLabel(Integer i) {
+    switch (i) {
+      case null -> System.out.println("value unavailable: " + i);
+      default -> System.out.println("other integer: " + i);
+      case -1, 1 -> System.out.println("absolute value 1: " + i);
+      case Integer value when value > 0 -> System.out.println("positive integer: " + i);
+    }
+  }
+}
diff --git a/tests/features1920/java20/SwitchPatternPreview4OK.java b/tests/features1920/java20/SwitchPatternPreview4OK.java
new file mode 100644
index 000000000..f5518d496
--- /dev/null
+++ b/tests/features1920/java20/SwitchPatternPreview4OK.java
@@ -0,0 +1,147 @@
+import java.util.List;
+import java.util.Locale;
+
+/**
+ * Inspired by examples in https://openjdk.org/jeps/427
+ */
+public class SwitchPatternPreview4OK {
+  public static void main(String[] args) {
+
+    System.out.println(formatterPatternSwitch(null));
+    System.out.println(formatterPatternSwitch(123));
+    System.out.println(formatterPatternSwitch(999L));
+    System.out.println(formatterPatternSwitch(12.34));
+    System.out.println(formatterPatternSwitch("foo"));
+    System.out.println(formatterPatternSwitch(List.of(123, "foo", 999L, 12.34)));
+
+    System.out.println(testCircle(new Rectangle()));
+    System.out.println(testCircle(new Circle(5)));
+    System.out.println(testCircle(new Circle(6)));
+
+    System.out.println(testSealedCoverage(new A()));
+    System.out.println(testSealedCoverage(new B()));
+    System.out.println(testSealedCoverage(new C(5)));
+
+//    constantLabelMustAppearBeforePattern(-1);
+//    constantLabelMustAppearBeforePattern(0);
+//    constantLabelMustAppearBeforePattern(42);
+//    constantLabelMustAppearBeforePattern(-99);
+//    constantLabelMustAppearBeforePattern(Integer.valueOf(123));
+//    constantLabelMustAppearBeforePattern(null);
+
+    constantLabelMustAppearBeforePatternInteger(-1);
+    constantLabelMustAppearBeforePatternInteger(0);
+    constantLabelMustAppearBeforePatternInteger(42);
+    constantLabelMustAppearBeforePatternInteger(-99);
+    constantLabelMustAppearBeforePatternInteger(Integer.valueOf(123));
+    constantLabelMustAppearBeforePatternInteger(null);
+
+//    System.out.println(testGenericSealedExhaustive(new E<Integer>()));
+  }
+
+  static String formatterPatternSwitch(Object o) {
+    return switch (o) {
+      case null      -> "null";
+      case Integer i -> String.format("int %d", i);
+      case Long l    -> String.format("long %d", l);
+      case Double d  -> String.format(Locale.ENGLISH, "double %f", d);
+      case String s  -> String.format("String %s", s);
+      default        -> o.toString();
+    };
+  }
+
+  static class Shape {}
+  static class Rectangle extends Shape {}
+  static class Circle extends Shape {
+    private final double radius;
+    public Circle(double radius) { this.radius = radius; }
+    double calculateArea() { return Math.PI * radius * radius; }
+  }
+
+  static String testCircle(Shape s) {
+    return switch (s) {
+      case Circle c when (c.calculateArea() > 100) -> "Large circle";
+      case Circle c -> "Small circle";
+      default -> "Non-circle";
+    };
+  }
+
+  sealed interface S permits A, B, C {}
+  final static class A implements S {}
+  final static class B implements S {}
+  static record C(int i) implements S {}  // Implicitly final
+
+  static String testSealedCoverage(S s) {
+    return switch (s) {
+      case A a -> "Sealed sub-class A";
+      case B b -> "Sealed sub-class B";
+      case C c -> "Sealed sub-record C";
+    };
+  }
+
+  /**
+   * According to an example from JEP 420, this should work, but it does not, neither with Javac nor ECJ.
+   *
+   * See:
+   *   https://openjdk.java.net/jeps/420#1b--Dominance-of-pattern-labels
+   *   https://bugs.openjdk.java.net/browse/JDK-8273326
+   *   https://bugs.eclipse.org/bugs/show_bug.cgi?id=579355
+   *
+   * TODO: reactivate when implemented or move to preview 5 with Java 21, Eclipse 4.28.
+   */
+/*
+  static String constantLabelMustAppearBeforePattern(Object o) {
+    switch (o) {
+      case null -> System.out.println("value unavailable: " + o);
+      case -1, 1 -> System.out.println("special case:" + o);
+      case Integer value when value > 0 -> System.out.println("positive integer: " + o);
+      case Integer i -> System.out.println("other integer: " + o);
+      default -> System.out.println("non-integer: " + o);
+    }
+    return o == null ? "null" : o.toString();
+  }
+*/
+
+  static String constantLabelMustAppearBeforePatternInteger(Integer i) {
+    switch (i) {
+      case null -> System.out.println("value unavailable: " + i);
+      case -1, 1 -> System.out.println("absolute value 1: " + i);
+      case Integer value when value > 0 -> System.out.println("positive integer: " + i);
+      default -> System.out.println("other integer: " + i);
+    }
+    return i == null ? "null" : i.toString();
+  }
+
+  static void nullCanAppearAfterConstantLabel(Integer i) {
+    switch (i) {
+      case -1, 1 -> System.out.println("absolute value 1: " + i);
+      case null -> System.out.println("value unavailable: " + i);
+      case Integer value when value > 0 -> System.out.println("positive integer: " + i);
+      default -> System.out.println("other integer: " + i);
+    }
+  }
+
+  /**
+   * According to an example from JEP 420, this should work with preview 2 (Java 18), and it does with Javac,
+   * but not with ECJ for Java 18, 19 and 20.
+   *
+   * See:
+   *   https://openjdk.java.net/jeps/420#2--Exhaustiveness-of-switch-expressions-and-statements
+   *   https://bugs.eclipse.org/bugs/show_bug.cgi?id=579360
+   *   https://github.com/eclipse-jdt/eclipse.jdt.core/issues/587
+   *
+   * TODO: reactivate when implemented or move to preview 5 with Java 21.
+   */
+/*
+  sealed interface I<T> permits D, E {}
+  final static class D<X> implements I<String> {}
+  final static class E<Y> implements I<Y> {}
+
+  static int testGenericSealedExhaustive(I<Integer> i) {
+    return switch (i) {
+      // Exhaustive as no D case possible!
+      case E<Integer> bi -> 42;
+    };
+  }
+*/
+}