diff --git a/backend/src/test/java/de/grimsi/gameyfin/util/FilenameUtilTest.java b/backend/src/test/java/de/grimsi/gameyfin/util/FilenameUtilTest.java
index 9ea385b..306dcf5 100644
--- a/backend/src/test/java/de/grimsi/gameyfin/util/FilenameUtilTest.java
+++ b/backend/src/test/java/de/grimsi/gameyfin/util/FilenameUtilTest.java
@@ -2,14 +2,18 @@ package de.grimsi.gameyfin.util;
 
 import com.google.common.jimfs.Configuration;
 import com.google.common.jimfs.Jimfs;
+import org.apache.commons.io.FileUtils;
 import org.junit.jupiter.api.AfterAll;
-import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.Arguments;
 import org.junit.jupiter.params.provider.MethodSource;
 
 import java.io.IOException;
 import java.nio.file.FileSystem;
+import java.nio.file.FileSystems;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.List;
@@ -24,10 +28,16 @@ class FilenameUtilTest {
     private static final FileSystem unixFS = Jimfs.newFileSystem(Configuration.unix());
     private static final FileSystem osxFS = Jimfs.newFileSystem(Configuration.osX());
     private static final FileSystem winFS = Jimfs.newFileSystem(Configuration.windows());
+
     private static final List<String> gameFileExtensions = List.of("extension_1", "extension_2", "extension_3");
 
+    @BeforeAll
+    static void init() {
+        new FilenameUtil().setPossibleGameFileExtensions(gameFileExtensions);
+    }
+
     @AfterAll
-    static void close() throws IOException {
+    static void closeFileSystems() throws IOException {
         unixFS.close();
         osxFS.close();
         winFS.close();
@@ -44,6 +54,8 @@ class FilenameUtilTest {
         String result = FilenameUtil.getFilenameWithoutExtension(p);
 
         assertThat(result).isEqualTo(filename);
+
+        Files.deleteIfExists(p);
     }
 
     @ParameterizedTest
@@ -57,30 +69,49 @@ class FilenameUtilTest {
         String result = FilenameUtil.getFilenameWithoutExtension(p);
 
         assertThat(result).isEqualTo("%s.%s".formatted(filename, gameFileExtensions.get(0)));
+
+        Files.deleteIfExists(p);
     }
 
-    @Test
-    void getFilenameWithExtension_Unix() {
+    @ParameterizedTest
+    @MethodSource("fileSystems")
+    void getFilenameWithExtension(FileSystem fileSystem) throws IOException {
+        String filename = "example_file";
+
+        Path p = fileSystem.getPath("%s.%s".formatted(filename, gameFileExtensions.get(0)));
+        Files.createFile(p);
+
+        String result = FilenameUtil.getFilenameWithExtension(p);
+
+        assertThat(result).isEqualTo("%s.%s".formatted(filename, gameFileExtensions.get(0)));
+
+        Files.deleteIfExists(p);
     }
 
-    @Test
-    void getFilenameWithExtension_OSX() {
+    @ParameterizedTest
+    @MethodSource("fileSystems")
+    void hasGameArchiveExtension_gameArchive(FileSystem fileSystem) throws IOException {
+        String filename = "example_file";
+
+        Path p = fileSystem.getPath("%s.%s".formatted(filename, gameFileExtensions.get(0)));
+        Files.createFile(p);
+
+        assertThat(FilenameUtil.hasGameArchiveExtension(p)).isTrue();
+
+        Files.deleteIfExists(p);
     }
 
-    @Test
-    void getFilenameWithExtension_Windows() {
-    }
+    @ParameterizedTest
+    @MethodSource("fileSystems")
+    void hasGameArchiveExtension_notGameArchive(FileSystem fileSystem) throws IOException {
+        String filename = "example_file";
 
-    @Test
-    void hasGameArchiveExtension_Unix() {
-    }
+        Path p = fileSystem.getPath("%s.%s".formatted(filename, "some_other_extension"));
+        Files.createFile(p);
 
-    @Test
-    void hasGameArchiveExtension_OSX() {
-    }
+        assertThat(FilenameUtil.hasGameArchiveExtension(p)).isFalse();
 
-    @Test
-    void hasGameArchiveExtension_Windows() {
+        Files.deleteIfExists(p);
     }
 
     private static Stream<Arguments> fileSystems() {