diff --git a/tests/mocks/core/common.php b/tests/mocks/core/common.php
index b073f23..9eb6b09 100644
--- a/tests/mocks/core/common.php
+++ b/tests/mocks/core/common.php
@@ -87,40 +87,6 @@
 	}
 }
 
-// This is sort of meh. Should probably be mocked up with
-// controllable output, so that we can test some of our
-// security code. The function itself will be tested in the
-// bootstrap testsuite.
-// --------------------------------------------------------------------
-
-if ( ! function_exists('remove_invisible_characters'))
-{
-	function remove_invisible_characters($str, $url_encoded = TRUE)
-	{
-		$non_displayables = array();
-
-		// every control character except newline (dec 10)
-		// carriage return (dec 13), and horizontal tab (dec 09)
-
-		if ($url_encoded)
-		{
-			$non_displayables[] = '/%0[0-8bcef]/';	// url encoded 00-08, 11, 12, 14, 15
-			$non_displayables[] = '/%1[0-9a-f]/';	// url encoded 16-31
-		}
-
-		$non_displayables[] = '/[\x00-\x08\x0B\x0C\x0E-\x1F\x7F]+/S';	// 00-08, 11, 12, 14-31, 127
-
-		do
-		{
-			$str = preg_replace($non_displayables, '', $str, -1, $count);
-		}
-		while ($count);
-
-		return $str;
-	}
-}
-
-
 // Clean up error messages
 // --------------------------------------------------------------------
 
@@ -150,23 +116,6 @@
 
 // We assume a few things about our environment ...
 // --------------------------------------------------------------------
-
-if ( ! function_exists('is_php'))
-{
-	function is_php($version = '5.0.0')
-	{
-		return ! (version_compare(PHP_VERSION, $version) < 0);
-	}
-}
-
-if ( ! function_exists('is_really_writable'))
-{
-	function is_really_writable($file)
-	{
-		return is_writable($file);
-	}
-}
-
 if ( ! function_exists('is_loaded'))
 {
 	function &is_loaded()