Not everbody has PHP 5.4 just yet.

sebastianbergmann · sebastianbergmann · commit ab901b0c2f8d · 2011-01-12T07:43:16.000+01:00
diff --git a/PHP/CodeCoverage/Util.php b/PHP/CodeCoverage/Util.php
@@ -47,6 +47,13 @@
     define('T_NAMESPACE', 377);
 }
 
+if (!function_exists('trait_exists')) {
+    function trait_exists($name)
+    {
+        return FALSE;
+    }
+}
+
 /**
  * Utility methods.
  *

Original file line number	Diff line number	Diff line change
`@@ -47,6 +47,13 @@`
`47`	`47`	`define('T_NAMESPACE', 377);`
`48`	`48`	`}`
`49`	`49`
	`50`	`+if (!function_exists('trait_exists')) {`
	`51`	`+ function trait_exists($name)`
	`52`	`+ {`
	`53`	`+ return FALSE;`
	`54`	`+ }`
	`55`	`+}`
	`56`	`+`
`50`	`57`	`/**`
`51`	`58`	`* Utility methods.`
`52`	`59`	`*`