Painless: add tests for cached boxing (#24163)

We had a TODO about adding tests around cached boxing. In #24077
I tracked down the uncached boxing tests and saw the TODO. Cached
boxing testing is a fairly small extension to that work.

modules/lang-painless/src/test/java/org/elasticsearch/painless/EqualsTests.java

@@ -23,7 +23,6 @@ import org.elasticsearch.test.ESTestCase;
 
 import static java.util.Collections.singletonMap;
 
-// TODO: Figure out a way to test autobox caching properly from methods such as Integer.valueOf(int);
 public class EqualsTests extends ScriptTestCase {
     public void testTypesEquals() {
         assertEquals(true, exec("return false === false;"));
@@ -133,7 +132,7 @@ public class EqualsTests extends ScriptTestCase {
         assertEquals(0, exec("def a = 1; Object b = new HashMap(); if (a === (Object)b) return 1; else return 0;"));
     }
     
-    public void testBranchEqualsDefAndPrimitive() {
+    public void testEqualsDefAndPrimitive() {
         /* This test needs an Integer that isn't cached by Integer.valueOf so we draw one randomly. We can't use any fixed integer because
          * we can never be sure that the JVM hasn't configured itself to cache that Integer. It is sneaky like that. */
         int uncachedAutoboxedInt = randomValueOtherThanMany(i -> Integer.valueOf(i) == Integer.valueOf(i), ESTestCase::randomInt);
@@ -141,6 +140,15 @@ public class EqualsTests extends ScriptTestCase {
         assertEquals(false, exec("def x = params.i; int y = params.i; return x === y;", singletonMap("i", uncachedAutoboxedInt), true));
         assertEquals(true, exec("def x = params.i; int y = params.i; return y == x;", singletonMap("i", uncachedAutoboxedInt), true));
         assertEquals(false, exec("def x = params.i; int y = params.i; return y === x;", singletonMap("i", uncachedAutoboxedInt), true));
+
+        /* Now check that we use valueOf with the boxing used for comparing primitives to def. For this we need an
+         * integer that is cached by Integer.valueOf. The JLS says 0 should always be cached. */
+        int cachedAutoboxedInt = 0;
+        assertSame(Integer.valueOf(cachedAutoboxedInt), Integer.valueOf(cachedAutoboxedInt));
+        assertEquals(true, exec("def x = params.i; int y = params.i; return x == y;", singletonMap("i", cachedAutoboxedInt), true));
+        assertEquals(true, exec("def x = params.i; int y = params.i; return x === y;", singletonMap("i", cachedAutoboxedInt), true));
+        assertEquals(true, exec("def x = params.i; int y = params.i; return y == x;", singletonMap("i", cachedAutoboxedInt), true));
+        assertEquals(true, exec("def x = params.i; int y = params.i; return y === x;", singletonMap("i", cachedAutoboxedInt), true));
     }
 
     public void testBranchNotEquals() {
@@ -153,7 +161,7 @@ public class EqualsTests extends ScriptTestCase {
         assertEquals(1, exec("def a = 1; Object b = new HashMap(); if (a !== (Object)b) return 1; else return 0;"));
     }
 
-    public void testBranchNotEqualsDefAndPrimitive() {
+    public void testNotEqualsDefAndPrimitive() {
         /* This test needs an Integer that isn't cached by Integer.valueOf so we draw one randomly. We can't use any fixed integer because
          * we can never be sure that the JVM hasn't configured itself to cache that Integer. It is sneaky like that. */
         int uncachedAutoboxedInt = randomValueOtherThanMany(i -> Integer.valueOf(i) == Integer.valueOf(i), ESTestCase::randomInt);
@@ -161,6 +169,15 @@ public class EqualsTests extends ScriptTestCase {
         assertEquals(true,  exec("def x = params.i; int y = params.i; return x !== y;", singletonMap("i", uncachedAutoboxedInt), true));
         assertEquals(false, exec("def x = params.i; int y = params.i; return y != x;", singletonMap("i", uncachedAutoboxedInt), true));
         assertEquals(true,  exec("def x = params.i; int y = params.i; return y !== x;", singletonMap("i", uncachedAutoboxedInt), true));
+
+        /* Now check that we use valueOf with the boxing used for comparing primitives to def. For this we need an
+         * integer that is cached by Integer.valueOf. The JLS says 0 should always be cached. */
+        int cachedAutoboxedInt = 0;
+        assertSame(Integer.valueOf(cachedAutoboxedInt), Integer.valueOf(cachedAutoboxedInt));
+        assertEquals(false, exec("def x = params.i; int y = params.i; return x != y;", singletonMap("i", cachedAutoboxedInt), true));
+        assertEquals(false,  exec("def x = params.i; int y = params.i; return x !== y;", singletonMap("i", cachedAutoboxedInt), true));
+        assertEquals(false, exec("def x = params.i; int y = params.i; return y != x;", singletonMap("i", cachedAutoboxedInt), true));
+        assertEquals(false,  exec("def x = params.i; int y = params.i; return y !== x;", singletonMap("i", cachedAutoboxedInt), true));
     }
 
     public void testRightHandNull() {