Why does drupal_lookup_path() return NULL?

Question

In a Drupal 7 site, I installed the Pathauto module. The user account I am using to log in has the permission to create new path aliases.

When I manually create a node, unselect the checkbox for automatic alias generation, and enter a custom alias (for example, qwerty), I can use drupal_lookup_path() to get the path alias.

$path = drupal_lookup_path('node/' . $node->nid);

However, using the following code in a test doesn't work.

$edit = array(
  'title' => 'asdf',
  'path[alias]' => 'qwerty',
);
$this->drupalPost("node/add/{$this->content_type}", $edit, t('Save'));

$path = drupal_lookup_path('node/' . $node->nid);

The value of $path is NULL, even when the path alias exists and $this->drupalGet('qwerty') returns a 200 status.

Why is drupal_lookup_path() failing to find the path alias only when called from a test?

Answer 1

I tracked this down to the fact that current_path(), which returns path/to/content in the browser, instead returns batch when called from within Simpletest.

Since drupal_lookup_path() uses the output of current_path() to generate the $cache[map] variable that it uses to find and store the path alias, this prevents drupal_lookup_path() from working in tests.

I have filed this as an issue on d.o.