Support disabling fetching by ENV variable

Author: petrkotek

src/PHPUnit/Listeners/NaughtyTestListener.php

@@ -21,6 +21,8 @@ class NaughtyTestListener extends BaseTestListener
     /** @var string Config key enabling execution of MetricFetcher before & after running all tests (bool) */
     const CONFIG_KEY_LEVEL_GLOBAL = 'executeOnGlobalLevel';
 
+    const DISABLE_ENV_KEY = 'DISABLE_NAUGHTY_TEST_DETECTOR';
+
     private $defaultOptions = [
         self::CONFIG_KEY_LEVEL_TEST => false,
         self::CONFIG_KEY_LEVEL_SUITE => true,
@@ -60,7 +62,8 @@ public function __construct(
         array $constructorArgs = [],
         array $options = []
     ) {
-        if ($metricFetcherClass !== null) {
+        $disabledByEnv = in_array(getenv(self::DISABLE_ENV_KEY), ['1', 'true', 'TRUE'], true);
+        if (!$disabledByEnv && $metricFetcherClass !== null) {
             $this->metricFetcher = new $metricFetcherClass(...$constructorArgs);
         }
         $this->flags = array_merge($this->defaultOptions, $options);

tests/PHPUnit/Listeners/NaughtyTestListenerTest.php

@@ -205,6 +205,27 @@ public function testAllLevels()
         ], $output);
     }
 
+    public function testDisabledByEnv()
+    {
+        // setup env
+        putenv('DISABLE_NAUGHTY_TEST_DETECTOR=1');
+
+        $testListener = new NaughtyTestListener('NonExistingClassName', [], [
+            NaughtyTestListener::CONFIG_KEY_LEVEL_GLOBAL => true,
+            NaughtyTestListener::CONFIG_KEY_LEVEL_SUITE => true,
+            NaughtyTestListener::CONFIG_KEY_LEVEL_TEST => true,
+        ]);
+
+        $this->startOutputCapture();
+        $this->runTestSuites($testListener, [1, 1]);
+        $output = $this->finishOutputCapture();
+
+        static::assertSame('', $output);
+
+        // revert env
+        putenv('DISABLE_NAUGHTY_TEST_DETECTOR=');
+    }
+
     private function createTestSuiteMock($name)
     {
         $mock = $this->getMock(TestSuite::class);