Adds PSR-16 integration test for Filesystem adapter

None of the setMultiple* tests appear to work; they each produce
`unserialize()` errors.

test/Psr/SimpleCache/FilesystemIntegrationTest.php

@@ -0,0 +1,99 @@
+<?php
+/**
+ * @see       https://github.com/zendframework/zend-cache for the canonical source repository
+ * @copyright Copyright (c) 2018 Zend Technologies USA Inc. (https://www.zend.com)
+ * @license   https://github.com/zendframework/zend-cache/blob/master/LICENSE.md New BSD License
+ */
+
+namespace ZendTest\Cache\Psr\SimpleCache;
+
+use Cache\IntegrationTests\SimpleCacheTest;
+use DirectoryIterator;
+use Zend\Cache\Psr\SimpleCacheDecorator;
+use Zend\Cache\Storage\Adapter\Filesystem;
+use Zend\Cache\Storage\Adapter\FilesystemOptions;
+
+class FilesystemIntegrationTest extends SimpleCacheTest
+{
+    /** @var string */
+    private $tmpCacheDir;
+
+    /** @var int */
+    protected $umask;
+
+    public function setUp()
+    {
+        $this->umask = umask();
+
+        if (getenv('TESTS_ZEND_CACHE_FILESYSTEM_DIR')) {
+            $cacheDir = getenv('TESTS_ZEND_CACHE_FILESYSTEM_DIR');
+        } else {
+            $cacheDir = sys_get_temp_dir();
+        }
+
+        $this->tmpCacheDir = @tempnam($cacheDir, 'zend_cache_test_');
+        if (! $this->tmpCacheDir) {
+            $err = error_get_last();
+            $this->fail("Can't create temporary cache directory-file: {$err['message']}");
+        } elseif (! @unlink($this->tmpCacheDir)) {
+            $err = error_get_last();
+            $this->fail("Can't remove temporary cache directory-file: {$err['message']}");
+        } elseif (! @mkdir($this->tmpCacheDir, 0777)) {
+            $err = error_get_last();
+            $this->fail("Can't create temporary cache directory: {$err['message']}");
+        }
+
+        $ttlMessage = 'Filesystem adapter does not honor TTL';
+        $keyMessage = 'Filesystem adapter supports a subset of PSR-16 characters for keys';
+
+        $this->skippedTests['testSetTtl'] = $ttlMessage;
+        $this->skippedTests['testSetMultipleTtl'] = $ttlMessage;
+        $this->skippedTests['testSetValidKeys'] = $keyMessage;
+        $this->skippedTests['testSetMultipleValidKeys'] = $keyMessage;
+
+        parent::setUp();
+    }
+
+    public function tearDown()
+    {
+        $this->removeRecursive($this->tmpCacheDir);
+
+        if ($this->umask != umask()) {
+            umask($this->umask);
+            $this->fail('Umask was not reset');
+        }
+
+        parent::tearDown();
+    }
+
+    public function removeRecursive($dir)
+    {
+        if (file_exists($dir)) {
+            $dirIt = new DirectoryIterator($dir);
+            foreach ($dirIt as $entry) {
+                $fname = $entry->getFilename();
+                if ($fname == '.' || $fname == '..') {
+                    continue;
+                }
+
+                if ($entry->isFile()) {
+                    unlink($entry->getPathname());
+                } else {
+                    $this->removeRecursive($entry->getPathname());
+                }
+            }
+
+            rmdir($dir);
+        }
+    }
+
+    public function createSimpleCache()
+    {
+        $storage = new Filesystem();
+        $storage->setOptions(new FilesystemOptions([
+            'cache_dir' => $this->tmpCacheDir,
+        ]));
+
+        return new SimpleCacheDecorator($storage);
+    }
+}