(bug 41042) Regression: API action=parse with nonexistent page

Changeset Iec98e472 changed the behavior of action=parse&page=... when
passed a page that does not exist: previously, it would return a
"missingtitle" error instead of assuming an empty page. As some people
had been depending on this old behavior, restore the error checking.

Change-Id: I4c76ce458ceb01e233c6074cd9251879013ec143

RELEASE-NOTES-1.21

@@ -47,6 +47,7 @@ production.
   page content; See docs/contenthandler.txt for details.
 * (bug 35693) ApiQueryImageInfo now suppresses errors when unserializing metadata.
 * (bug 40111) Disable minor edit for page/section creation by API
+* (bug 41042) Revert change to action=parse&page=... behavior when the page does not exist.
 
 === Languages updated in 1.21 ===
 

includes/api/ApiParse.php

@@ -147,6 +147,9 @@ class ApiParse extends ApiBase {
 
 				$pageObj = $this->getTitleOrPageId( $pageParams, 'fromdb' );
 				$titleObj = $pageObj->getTitle();
+				if ( !$titleObj || !$titleObj->exists() ) {
+					$this->dieUsage( "The page you specified doesn't exist", 'missingtitle' );
+				}
 				$wgTitle = $titleObj;
 
 				if ( isset( $prop['revid'] ) ) {

tests/phpunit/includes/api/ApiParseTest.php

@@ -0,0 +1,29 @@
+<?php
+
+/**
+ * @group API
+ * @group Database
+ */
+class ApiParseTest extends ApiTestCase {
+
+	protected function setUp() {
+		parent::setUp();
+		$this->doLogin();
+	}
+
+	function testParseNonexistentPage() {
+		$somePage = mt_rand();
+
+		try {
+			$data = $this->doApiRequest( array(
+				'action' => 'parse',
+				'page' => $somePage ) );
+
+			$this->fail( "API did not return an error when parsing a nonexistent page" );
+		} catch(UsageException $ex){
+			$this->assertEquals( 'missingtitle', $ex->getCodeString(),
+				"Parse request for nonexistent page must give 'missingtitle' error: " . var_export( $ex->getMessageArray(), true ) );
+		}
+	}
+
+}