test: Add a router script for the built-in server to initialize SSP's configuration.

With this script, which will be executed for every request performed to the built-in server, we can preload the configuration from a temporary file, making it possible to configure SimpleSAMLphp dynamically when testing.

tests/routers/configLoader.php

+<?php
+
+/*
+ * This "router" (a script that's executed for every request received by PHP's built-in web server) will look
+ * for a file in the system's temporary directory, with the PID of the current process as its name, and the
+ * '.lock' extension. If the file exists, it will try to include it and preload SimpleSAMLphp's configuration with
+ * the $config array defined in that file.
+ * This is useful to configure SimpleSAMLphp dynamically when running inside the built-in server, so that
+ * we can test different configurations without the need to keep a structure of files.
+ *
+ * In order to use it:
+ *
+ * 1. Create an array with the SimpleSAMLphp configuration you would like to use.
+ * 2. Start the built-in server passing "configLoader" as the first parameter to the constructor:
+ *      $server = new BuiltInServer('configLoader');
+ *      $addr = $server->start();
+ * 3. Get the PID of the server once it has started:
+ *      $pid = $server->getPid();
+ * 4. Build the path to the file that this script will use:
+ *      $file = sys_get_temp_dir().'/'.$pid.'.lock';
+ * 5. Dump the configuration array to the file:
+ *      file_put_contents("<?php\n\$config = ".var_export($config, true).";\n");
+ * 6. Make a request to the server:
+ *      $server->get($query, $parameters);
+ * 7. Remove the temporary file when done:
+ *      unlink($file);
+ */
+
+include_once(sys_get_temp_dir().'/'.getmypid().'.lock');
+
+// load SimpleSAMLphp's autoloader
+require_once(dirname(__FILE__).'/../../vendor/autoload.php');
+
+// initialize configuration
+if (isset($config)) {
+    SimpleSAML_Configuration::loadFromArray($config, '[ARRAY]', 'simplesaml');
+}
+
+// let the script proceed
+// see: http://php.net/manual/en/features.commandline.webserver.php
+return false;