Index: includes/bootstrap.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/bootstrap.inc,v
retrieving revision 1.220
diff -u -p -r1.220 bootstrap.inc
--- includes/bootstrap.inc	21 Aug 2008 19:36:36 -0000	1.220
+++ includes/bootstrap.inc	3 Sep 2008 08:45:57 -0000
@@ -1135,14 +1135,20 @@ function drupal_init_language() {
  * Get a list of languages set up indexed by the specified key
  *
  * @param $field The field to index the list with.
- * @param $reset Boolean to request a reset of the list.
+ * @param $reset Boolean to request a reset of the list,
+ *  or (internal) an array of languages to feed that function with.
  */
 function language_list($field = 'language', $reset = FALSE) {
   static $languages = NULL;
 
   // Reset language list
   if ($reset) {
-    $languages = NULL;
+    if (is_array($reset)) {
+      $languages = $reset;
+    }
+    else {
+      $languages = NULL;
+    }
   }
 
   // Init language list
Index: modules/simpletest/tests/language.test
===================================================================
RCS file: modules/simpletest/tests/language.test
diff -N modules/simpletest/tests/language.test
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ modules/simpletest/tests/language.test	3 Sep 2008 10:19:49 -0000
@@ -0,0 +1,108 @@
+<?php
+// $Id $
+
+class LanguageTestCase extends DrupalWebTestCase {
+
+  /**
+   * Implementation of getInfo().
+   */
+  function getInfo() {
+    return array(
+      'name' => t('Language negotiation test'),
+      'description' => t('Test the behavior of the language negotiation subsystem.'),
+      'group' => t('System')
+    );
+  }
+
+  /**
+   * Implementation of setUp().
+   */
+  function setUp() {
+    parent::setUp('locale');
+  }
+  
+  /**
+   * Unit tests for the language_from_browser() function.
+   */
+  function testLanguageFromBrowser() {
+    $languages = array(
+      'language' => array(
+        // In our test case, 'en' has priority over 'en-US'.
+        'en' => (object) array(
+          'language' => 'en',
+          'enabled' => 1,
+          'weight' => 1,
+        ),
+        'en-US' => (object) array(
+          'language' => 'en-US',
+          'enabled' => 1,
+          'weight' => 0.6,
+        ),
+        // But 'fr-CA' has priority over 'fr'.
+        'fr-CA' => (object) array(
+          'language' => 'fr-CA',
+          'enabled' => 1,
+          'weight' => 0.5,
+        ),
+        'fr' => (object) array(
+          'language' => 'fr',
+          'enabled' => 1,
+          'weight' => 0.4,
+        ),
+        // And 'es-MX' is alone.
+        'es-MX' => (object) array(
+          'language' => 'es-MX',
+          'enabled' => 1,
+          'weight' => 0.3,
+        ),
+      )
+    );
+
+    drupal_function_exists('language_from_browser');
+
+    // Initialize the language list.
+    language_list('language', $languages);
+
+    $test_cases = array(
+      // Equal qvalue for each language, choose the site prefered one.
+      'en,en-US,fr-CA,fr,es-MX' => 'en',
+      'fr,en' => 'en',
+      'en,fr' => 'en',
+      'en-US,fr' => 'en-US',
+      'fr,en-US' => 'en-US',
+      'fr' => 'fr-CA',
+      'fr,es-MX' => 'fr-CA',
+      'fr,es' => 'fr-CA',
+      'es,fr' => 'fr-CA',
+      'es-MX,de' => 'es-MX',
+      'de,es-MX' => 'es-MX',
+
+      // Different qvalues.
+      'en-US,en;q=0.5,fr;q=0.25' => 'en-US',
+      'fr,en;q=0.5' => 'fr-CA',
+      'fr,en;q=0.5,fr-CA;q=0.25' => 'fr',
+
+      // Those should be equivalent, because a selector matches all sub-languages
+      'es-MX,en;q=0.5' => 'es-MX',
+      'es,en;q=0.5' => 'es-MX',
+
+      // Silly wildcards are also valid.
+      '*,fr-CA;q=0.5' => 'en',
+      '*,en;q=0.25' => 'fr-CA',
+      'en,en-US;q=0.5,fr;q=0.25' => 'en',
+      'en-US,en;q=0.5,fr;q=0.25' => 'en-US',
+      
+      // Unresolvable cases.
+      '' => NULL,
+      'de,pl' => NULL,
+      $this->randomName(10) => NULL,
+    );
+    
+    foreach ($test_cases as $accept_language => $expected_result) {
+      $_SERVER['HTTP_ACCEPT_LANGUAGE'] = $accept_language;
+      $result = language_from_browser();
+      $this->assertIdentical(isset($result->language) ? $result->language : NULL, $expected_result, t("Language selection '@accept-language' selects '@result', result = '@actual'", array('@accept-language' => $accept_language, '@result' => $expected_result, '@actual' => isset($result->language) ? $result->language : 'none')));
+    }
+  }
+}
+