Un-trash validation post status to re-use instead of adding new post …

…with duplicated name

includes/utils/class-amp-validation-utils.php

@@ -1066,7 +1066,13 @@ public static function store_validation_errors( $validation_errors, $url ) {
 
 		// If there already exists a post for the given validation errors, just amend the $url to the existing post.
 		$post_for_other_url = get_page_by_path( $post_name, OBJECT, self::POST_TYPE_SLUG );
+		if ( ! $post_for_other_url ) {
+			$post_for_other_url = get_page_by_path( $post_name . '__trashed', OBJECT, self::POST_TYPE_SLUG );
+		}
 		if ( $post_for_other_url ) {
+			if ( 'trash' === $post_for_other_url->post_status ) {
+				wp_untrash_post( $post_for_other_url->ID );
+			}
 			if ( ! in_array( $url, get_post_meta( $post_for_other_url->ID, self::AMP_URL_META, false ), true ) ) {
 				add_post_meta( $post_for_other_url->ID, self::AMP_URL_META, wp_slash( $url ), false );
 			}

tests/test-class-amp-validation-utils.php

@@ -624,7 +624,7 @@ public function test_register_post_type() {
 	 * @covers AMP_Validation_Utils::store_validation_errors()
 	 */
 	public function test_store_validation_errors() {
-		global $post, $wp;
+		global $post;
 		$post = $this->factory()->post->create_and_get(); // WPCS: global override ok.
 		add_theme_support( 'amp' );
 		AMP_Validation_Utils::process_markup( '<!--amp-source-stack:plugin:foo-->' . $this->disallowed_tag . '<!--/amp-source-stack:plugin:foo-->' );
@@ -703,6 +703,35 @@ public function test_store_validation_errors() {
 		remove_theme_support( 'amp' );
 	}
 
+	/**
+	 * Test for store_validation_errors() when existing post is trashed.
+	 *
+	 * @covers AMP_Validation_Utils::store_validation_errors()
+	 */
+	public function test_store_validation_errors_untrashing() {
+		$validation_errors = $this->get_mock_errors();
+
+		$first_post_id = AMP_Validation_Utils::store_validation_errors( $validation_errors, home_url( '/foo/' ) );
+		$this->assertInternalType( 'int', $first_post_id );
+
+		$post_name = get_post( $first_post_id )->post_name;
+		wp_trash_post( $first_post_id );
+		$this->assertEquals( $post_name . '__trashed', get_post( $first_post_id )->post_name );
+
+		$next_post_id = AMP_Validation_Utils::store_validation_errors( $validation_errors, home_url( '/bar/' ) );
+		$this->assertInternalType( 'int', $next_post_id );
+		$this->assertEquals( $post_name, get_post( $next_post_id )->post_name );
+		$this->assertEquals( $next_post_id, $first_post_id );
+
+		$this->assertEqualSets(
+			array(
+				home_url( '/foo/' ),
+				home_url( '/bar/' ),
+			),
+			get_post_meta( $next_post_id, AMP_Validation_Utils::AMP_URL_META, false )
+		);
+	}
+
 	/**
 	 * Test for get_validation_status_post().
 	 *