Test DRUPAL_NO_CACHE.
function testNoCache() {
$this
->setCacheMode(DRUPAL_NO_CACHE);
$current_content = $this
->randomName();
variable_set('block_test_content', $current_content);
// If DRUPAL_NO_CACHE has no effect, the next request would be cached.
$this
->drupalGet('');
$this
->assertText($current_content, 'Block content displays.');
// A cached copy should not be served.
$current_content = $this
->randomName();
variable_set('block_test_content', $current_content);
$this
->drupalGet('');
$this
->assertText($current_content, 'DRUPAL_NO_CACHE prevents blocks from being cached.');
}