adjust list of magic files

vendor/composer/installed.php is critical component of Composer's runtime API -
methods from \Composer\InstalledVersions class do not work without it. Include
this file in the mocked composer of 'happy path' tests.

Author: lavarou

agent/php_execute.c

@@ -1109,9 +1109,11 @@ static void nr_execute_handle_autoload_composer(const char* filename) {
 // Composer signature file"
 #define COMPOSER_MAGIC_FILE_1 "composer/autoload_real.php"
 #define COMPOSER_MAGIC_FILE_1_LEN (sizeof(COMPOSER_MAGIC_FILE_1) - 1)
-// Composer runtime API file:
+// Composer runtime API files:
 #define COMPOSER_MAGIC_FILE_2 "composer/InstalledVersions.php"
 #define COMPOSER_MAGIC_FILE_2_LEN (sizeof(COMPOSER_MAGIC_FILE_2) - 1)
+#define COMPOSER_MAGIC_FILE_3 "composer/installed.php"
+#define COMPOSER_MAGIC_FILE_3_LEN (sizeof(COMPOSER_MAGIC_FILE_3) - 1)
   char* vendor_path = NULL; // result of dirname(filename)
 
   vendor_path = nr_execute_handle_autoload_composer_get_vendor_path(filename);
@@ -1130,6 +1132,11 @@ static void nr_execute_handle_autoload_composer(const char* filename) {
     return;
   }
 
+  if (!nr_execute_handle_autoload_composer_file_exists(vendor_path, COMPOSER_MAGIC_FILE_3)) {
+    nrl_verbosedebug(NRL_FRAMEWORK, "'%s' not found in '%s'", COMPOSER_MAGIC_FILE_3, vendor_path);
+    return;
+  }
+
   nrl_verbosedebug(NRL_FRAMEWORK, "detected composer");
   NRPRG(txn)->composer_info.composer_detected = true;
   nr_fw_support_add_library_supportability_metric(NRPRG(txn), "Composer");

tests/integration/autoloader/autoload-with-composer/vendor/composer/installed.php

@@ -0,0 +1,11 @@
+<?php
+/*
+ * Copyright 2020 New Relic Corporation. All rights reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/*DESCRIPTION
+This file is needed by real Composer's runtime API, and agent verifies its presence to determine if Composer is used.
+Therefore, even though mocked version of Composer's runtime API does not use this file but (and that's why its empty),
+it still needs to be present.
+*/