MDL-85400 PHPunit: Hard to test code that uses encryption

This change stops the encryption code setting created key files to
read-only during PHPunit runs, which means they will be safely
deleted when the system resets after a test.

lib/classes/encryption.php

@@ -61,8 +61,8 @@ class encryption {
             throw new \moodle_exception('encryption_keyalreadyexists', 'error');
         }
 
-        // Don't make it read-only in Behat or it will fail to clear for future runs.
-        if (defined('BEHAT_SITE_RUNNING')) {
+        // Don't make it read-only in tests or it will fail to clear for future runs.
+        if (defined('BEHAT_SITE_RUNNING') || PHPUNIT_TEST) {
             $chmod = false;
         }
 

lib/tests/encryption_test.php

@@ -28,25 +28,8 @@ use advanced_testcase;
  */
 final class encryption_test extends advanced_testcase {
 
-    /**
-     * Clear junk created by tests.
-     */
-    protected function tearDown(): void {
-        global $CFG;
-
-        $keyfile = encryption::get_key_file(encryption::METHOD_SODIUM);
-        if (file_exists($keyfile)) {
-            chmod($keyfile, 0700);
-        }
-        remove_dir($CFG->dataroot . '/secret');
-        unset($CFG->nokeygeneration);
-        parent::tearDown();
-    }
-
     protected function setUp(): void {
         parent::setUp();
-        $this->tearDown();
-
         require_once(__DIR__ . '/fixtures/testable_encryption.php');
     }