Fix array assertEquals failure message when an element is null or non-null

CHANGES.txt

@@ -1,6 +1,7 @@
 Current (7.11.0)
 Fixed: GITHUB-3028: Execution stalls when using "use-global-thread-pool" (Krishnan Mahadevan)
 Fixed: GITHUB-3122: Update JCommander to 1.83 (Antoine Dessaigne)
+Fixed: GITHUB-3135: assertEquals on arrays - Failure message is missing information about the array index when an array element is unexpectedly null or non-null (Albert Choi)
 
 7.10.2
 Fixed: GITHUB-3117: ListenerComparator doesn't work (Krishnan Mahadevan)

testng-asserts/src/main/java/org/testng/Assert.java

@@ -1780,7 +1780,7 @@ public static void assertEquals(Object[] actual, Object[] expected, String messa
         continue;
       }
       if ((a == null && e != null) || (a != null && e == null)) {
-        failNotEquals(a, e, message);
+        failNotEquals(a, e, errorMessage);
       }
       // Compare by value for multi-dimensional array.
       if (e.getClass().isArray()) {

testng-asserts/src/test/java/org/testng/AssertTest.java

@@ -355,6 +355,33 @@ public void testInequalityMessage() {
     Assert.assertEquals("x", "y");
   }
 
+  @Test(
+      description = "GITHUB-3135",
+      expectedExceptions = AssertionError.class,
+      expectedExceptionsMessageRegExp =
+          "Arrays differ at element \\[2\\]: 3 != 5 expected \\[3\\] but found \\[5\\]")
+  public void testAssertEqualsArrayElementDiffers() {
+    Assert.assertEquals(new Integer[] {1, 2, 5}, new Integer[] {1, 2, 3});
+  }
+
+  @Test(
+      description = "GITHUB-3135",
+      expectedExceptions = AssertionError.class,
+      expectedExceptionsMessageRegExp =
+          "Arrays differ at element \\[2\\]: 3 != null expected \\[3\\] but found \\[null\\]")
+  public void testAssertEqualsArrayElementIsNull() {
+    Assert.assertEquals(new Integer[] {1, 2, null}, new Integer[] {1, 2, 3});
+  }
+
+  @Test(
+      description = "GITHUB-3135",
+      expectedExceptions = AssertionError.class,
+      expectedExceptionsMessageRegExp =
+          "Arrays differ at element \\[2\\]: null != 5 expected \\[null\\] but found \\[5\\]")
+  public void testAssertEqualsArrayElementIsNotNull() {
+    Assert.assertEquals(new Integer[] {1, 2, 5}, new Integer[] {1, 2, null});
+  }
+
   @Test
   public void testAssertEqualsNoOrder() {
     String[] actual = {"a", "b"};