Test bootstrap/printPHPCodeSnifferTestOutput(): bug fix

PR 2289 added a count of the number of test case files to the test output, however did not take into account that when only the unit tests for the utility functions would be run, i.e. `phpunit --filter FindExtendedClassNameTest`, the `$GLOBALS['PHP_CODESNIFFER_SNIFF_CASE_FILES']` variable would not have any arrays in it.

This adds some minor defensive coding which gets rid of the error messages which would be generated in that situation.

Author: jrfnl

tests/bootstrap.php

@@ -52,17 +52,33 @@ class_alias('PHPUnit_Framework_TestResult', 'PHPUnit'.'\Framework\TestResult');
  */
 function printPHPCodeSnifferTestOutput()
 {
+    echo PHP_EOL.PHP_EOL;
+
+    $output = 'The test files';
+    $data   = [];
+
     $codeCount = count($GLOBALS['PHP_CODESNIFFER_SNIFF_CODES']);
-    $files     = call_user_func_array('array_merge', $GLOBALS['PHP_CODESNIFFER_SNIFF_CASE_FILES']);
-    $files     = array_unique($files);
-    $fileCount = count($files);
+    if (empty($GLOBALS['PHP_CODESNIFFER_SNIFF_CASE_FILES']) === false) {
+        $files     = call_user_func_array('array_merge', $GLOBALS['PHP_CODESNIFFER_SNIFF_CASE_FILES']);
+        $files     = array_unique($files);
+        $fileCount = count($files);
+
+        $output = '%d sniff test files';
+        $data[] = $fileCount;
+    }
+
+    $output .= ' generated %d unique error codes';
+    $data[]  = $codeCount;
 
-    echo PHP_EOL.PHP_EOL;
-    echo "$fileCount sniff test files generated $codeCount unique error codes";
     if ($codeCount > 0) {
         $fixes   = count($GLOBALS['PHP_CODESNIFFER_FIXABLE_CODES']);
         $percent = round(($fixes / $codeCount * 100), 2);
-        echo "; $fixes were fixable ($percent%)";
+
+        $output .= '; %d were fixable (%d%%)';
+        $data[]  = $fixes;
+        $data[]  = $percent;
     }
 
+    vprintf($output, $data);
+
 }//end printPHPCodeSnifferTestOutput()