[Wasm] Add tests for jsenum boxing with partial inlining to check box…

…ing around cases such as `checkNotNull`

PiperOrigin-RevId: 592687191

transpiler/javatests/com/google/j2cl/integration/java/jsenum/Main.java

@@ -19,6 +19,7 @@
 import static com.google.j2cl.integration.testing.Asserts.assertFalse;
 import static com.google.j2cl.integration.testing.Asserts.assertThrows;
 import static com.google.j2cl.integration.testing.Asserts.assertThrowsClassCastException;
+import static com.google.j2cl.integration.testing.Asserts.assertThrowsNullPointerException;
 import static com.google.j2cl.integration.testing.Asserts.assertTrue;
 import static com.google.j2cl.integration.testing.Asserts.assertUnderlyingTypeEquals;
 import static com.google.j2cl.integration.testing.Asserts.fail;
@@ -72,6 +73,7 @@ public static void main(String... args) {
     testAutoBoxing_intersectionCasts();
     testSpecializedSuperType();
     testSpecializedSuperTypeUnderlyingType();
+    testBoxingPartialInlining();
   }
 
   @Wasm("nop") // TODO(b/288145698): Support native JsEnum.
@@ -925,4 +927,23 @@ private static Object passThrough(Object o) {
     assertTrue(o instanceof String || o instanceof Double || o instanceof Boolean);
     return o;
   }
+
+  private static void testBoxingPartialInlining() {
+    // TODO(b/315214896) Check the size difference to see if cases such as these take advantage of
+    // partial inlining in Wasm to turn this into a simple null check, avoiding boxing.
+    PlainJsEnum nonnullJsEnum = PlainJsEnum.ONE;
+    checkNotNull(nonnullJsEnum);
+    // Use the local so it doesn't get removed.
+    assertTrue(nonnullJsEnum == PlainJsEnum.ONE);
+
+    PlainJsEnum nullJsEnum = null;
+    assertThrowsNullPointerException(() -> checkNotNull(nullJsEnum));
+    assertTrue(nullJsEnum == null);
+  }
+
+  private static void checkNotNull(Object obj) {
+    if (obj == null) {
+      throw new NullPointerException();
+    }
+  }
 }