Change unit testing to match phpDocumentor itself

tests/coverage-checker.php

@@ -0,0 +1,31 @@
+<?php
+// based on https://ocramius.github.io/blog/automated-code-coverage-check-for-github-pull-requests-with-travis/
+$inputFile  = __DIR__ . '/../build/logs/clover.xml';
+$percentage = min(100, max(0, (int) $argv[1]));
+
+if (!file_exists($inputFile)) {
+    throw new InvalidArgumentException('Invalid input file provided');
+}
+
+if (!$percentage) {
+    throw new InvalidArgumentException('An integer checked percentage must be given as parameter');
+}
+
+$xml             = new SimpleXMLElement(file_get_contents($inputFile));
+$metrics         = $xml->xpath('//metrics');
+$totalElements   = 0;
+$checkedElements = 0;
+
+foreach ($metrics as $metric) {
+    $totalElements   += (int) $metric['elements'];
+    $checkedElements += (int) $metric['coveredelements'];
+}
+
+$coverage = ($checkedElements / $totalElements) * 100;
+
+if ($coverage < $percentage) {
+    echo 'Code coverage is ' . $coverage . '%, which is below the accepted ' . $percentage . '%' . PHP_EOL;
+    exit(1);
+}
+
+echo 'Code coverage is ' . $coverage . '% - OK!' . PHP_EOL;