Fix gzopen and user creation issues

tests/Unit/Extensions/HelperCoverUrlTest.php

@@ -8,6 +8,20 @@ use Tests\TestCase;
 
 class HelperCoverUrlTest extends TestCase
 {
+    public function test_unzip_gzip_file_returns_uncompressed_contents(): void
+    {
+        $path = tempnam(sys_get_temp_dir(), 'nntmux-gzip-');
+        $this->assertIsString($path);
+
+        file_put_contents($path, gzencode('gzip fixture contents'));
+
+        try {
+            $this->assertSame('gzip fixture contents', unzipGzipFile($path));
+        } finally {
+            @unlink($path);
+        }
+    }
+
     public function test_get_release_cover_returns_placeholder_for_negative_bookinfo_id(): void
     {
         $url = getReleaseCover((object) ['bookinfo_id' => -2]);