Correctly set $wgAutoCreateTempUser['matchPattern'] config in JS

Why:

* $wgAutoCreateTempUser['matchPattern'] is set to null by default
* In util.js, isTemporaryUser throws an error if the matchPattern
  is null, because it expects an array of strings.
* This means that with the default config, a JavaScript error is
  thrown.

What:

* If matchPattern is null, set it to an array containing genPattern,
  which is the same as what RealTempUserConfig::__construct does in
  PHP.

Bug: T367108
Change-Id: I22d3eb223dcc549335a62c3bca51319e37528a81

resources/src/mediawiki.util/util.js

@@ -1158,6 +1158,8 @@ var util = {
  var matchPatterns = config.AutoCreateTempUser.matchPattern;
  if ( typeof matchPatterns === 'string' ) {
  matchPatterns = [ matchPatterns ];
+ } else if ( matchPatterns === null ) {
+ matchPatterns = [ config.AutoCreateTempUser.genPattern ];
  }
  for ( var i = 0; i < matchPatterns.length; i++ ) {
  var autoCreateUserMatchPattern = matchPatterns[ i ];

tests/qunit/resources/mediawiki.util/util.test.js

@@ -838,6 +838,17 @@ QUnit.module( 'mediawiki.util', QUnit.newMwEnvironment( {
  assert.strictEqual( util.isTemporaryUser( username[ 1 ] ), username[ 2 ] );
  } );
 
+ QUnit.test.each( 'isTemporaryUser matchPattern null', {
+ 'prefix mismatch': [ '*$1', 'Test', false, true ],
+ 'prefix match': [ '*$1', '*Some user', true, true ]
+ }, ( assert, username ) => {
+ mw.util.setOptionsForTest( {
+ AutoCreateTempUser: { enabled: username[ 3 ], genPattern: username[ 0 ], matchPattern: null }
+ } );
+
+ assert.strictEqual( util.isTemporaryUser( username[ 1 ] ), username[ 2 ] );
+ } );
+
  QUnit.test( 'isInfinity', ( assert ) => {
  assert.true( util.isInfinity( 'indefinite' ) );
  assert.true( util.isInfinity( 'infinite' ) );