Index: wp-testcase/test-ajax-actions/test_admin_ajax_dim_comments.php
===================================================================
--- wp-testcase/test-ajax-actions/test_admin_ajax_dim_comments.php	(revision 676)
+++ wp-testcase/test-ajax-actions/test_admin_ajax_dim_comments.php	(working copy)
@@ -188,9 +188,14 @@
 		$_POST['_page']       = 1;
 		$_POST['_url']        = admin_url( 'edit-comments.php' );

-		// Make the request
-		$this->setExpectedException( 'WPAjaxDieException', (string) time() );
-		$this->_handleAjax( 'dim-comment' );
+		// Make the request, look for a timestamp in the exception
+		try {
+			$this->_handleAjax( 'dim-comment' );
+			$this->fail( 'Expected exception' );
+		} catch ( WPAjaxDieException $e ) {
+			$this->assertEquals( 10, strlen( $e->getMessage() ) );
+			$this->assertInternalType( 'integer', $e->getMessage() );
+		}
 	}