Tests: Fix failing malformed date test

Dates without leading zeros (e.g., `2012-1-08`, `2012-01-8`) are now correctly recognized as valid dates. This change fixes the test cases to correctly reflect that these formats are valid and fixes an undefined variable reference.

Follow-up to [61172].

Props wildworks, westonruter.
Fixes #26798.

git-svn-id: https://develop.svn.wordpress.org/trunk@61173 602fd350-edb4-49c9-b593-d223f7449a82

Author: t-hamano

tests/phpunit/tests/post.php

@@ -826,7 +826,7 @@ public function test_use_block_editor_for_post() {
 	 */
 	public function test_wp_insert_post_handle_malformed_post_date( $input, $expected ) {
 		$post = array(
-			'post_author'  => self::$editor_id,
+			'post_author'  => self::$user_ids['editor'],
 			'post_status'  => 'publish',
 			'post_content' => 'content',
 			'post_title'   => 'title',
@@ -893,37 +893,38 @@ public function data_wp_insert_post_handle_malformed_post_date() {
 				'2012-01-01 00:60:00',
 				true,
 			),
-			// Failures.
+			// Dates without leading zeros (valid but malformed format).
 			array(
-				'2012-08-0z',
-				false,
+				'2012-08-1',
+				true,
 			),
 			array(
-				'2012-08-1',
-				false,
+				'2012-1-08 00:00:00',
+				true,
 			),
 			array(
-				'201-01-08 00:00:00',
-				false,
+				'2012-01-8 00:00:00',
+				true,
 			),
+			// Failures.
 			array(
-				'201-01-08 00:60:00',
+				'2012-08-0z',
 				false,
 			),
 			array(
-				'201a-01-08 00:00:00',
+				'201-01-08 00:00:00',
 				false,
 			),
 			array(
-				'2012-1-08 00:00:00',
+				'201-01-08 00:60:00',
 				false,
 			),
 			array(
-				'2012-31-08 00:00:00',
+				'201a-01-08 00:00:00',
 				false,
 			),
 			array(
-				'2012-01-8 00:00:00',
+				'2012-31-08 00:00:00',
 				false,
 			),
 			array(
@@ -1016,24 +1017,25 @@ public function data_wp_resolve_post_date_regex() {
 				'2012-01-01 00:00:60',
 				'2012-01-01 00:00:60',
 			),
+			// Dates without leading zeros (valid but malformed format).
 			array(
-				'201-01-08',
-				false,
+				'2012-1-08',
+				'2012-1-08',
 			),
 			array(
-				'201a-01-08',
-				false,
+				'2012-01-8',
+				'2012-01-8',
 			),
 			array(
-				'2012-1-08',
+				'201-01-08',
 				false,
 			),
 			array(
-				'2012-31-08',
+				'201a-01-08',
 				false,
 			),
 			array(
-				'2012-01-8',
+				'2012-31-08',
 				false,
 			),
 			array(