diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..d724e8a
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,29 @@
+# Rust / Cargo
+/target
+**/*.rs.bk
+Cargo.lock
+*.pdb
+
+# IDEs
+.idea/
+.vscode/
+*.swp
+*.swo
+*~
+
+# OS
+.DS_Store
+Thumbs.db
+
+# Project-specific
+info/
+CLAUDE.md
+
+# Test artifacts
+/test/testverzeichnis
+
+# Temporary files
+*.tmp
+*.log
+*.bak
+
diff --git a/Cargo.lock b/Cargo.lock
index c0dc258..38641d5 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -7,6 +7,7 @@ name = "NameToUnix"
 version = "0.2.0"
 dependencies = [
  "anyhow",
+ "assert_cmd",
  "assert_fs",
  "clap",
  "dirs",
@@ -93,6 +94,21 @@ version = "1.0.97"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "dcfed56ad506cb2c684a14971b8861fdc3baaaae314b9e5f9bb532cbe3ba7a4f"
 
+[[package]]
+name = "assert_cmd"
+version = "2.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9c5bcfa8749ac45dd12cb11055aeeb6b27a3895560d60d71e3c23bf979e60514"
+dependencies = [
+ "anstyle",
+ "bstr",
+ "libc",
+ "predicates",
+ "predicates-core",
+ "predicates-tree",
+ "wait-timeout",
+]
+
 [[package]]
 name = "assert_fs"
 version = "1.1.2"
@@ -127,6 +143,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "531a9155a481e2ee699d4f98f43c0ca4ff8ee1bfd55c31e9e98fb29d2b176fe0"
 dependencies = [
  "memchr",
+ "regex-automata",
  "serde",
 ]
 
@@ -840,6 +857,15 @@ version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "06abde3611657adf66d383f00b093d7faecc7fa57071cce2578660c9f1010821"
 
+[[package]]
+name = "wait-timeout"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "09ac3b126d3914f9849036f826e054cbabdc8519970b8998ddaf3b5bd3c65f11"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "walkdir"
 version = "2.5.0"
diff --git a/Cargo.toml b/Cargo.toml
index a491460..71041b5 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -40,6 +40,7 @@ itertools = "0.12.1"        # Erweiterte Iterator-Funktionalität
 tempfile = "3.10.1"         # Temporäre Dateien für Tests
 assert_fs = "1.1.1"         # Dateisystem-Assertions für Tests
 predicates = "3.1.0"        # Prädikate für Tests
+assert_cmd = "2.0"          # Command-Line Testing
 
 [profile.release]
 lto = true                  # Link-Time-Optimierung
diff --git a/tests/integration_tests.rs b/tests/integration_tests.rs
new file mode 100644
index 0000000..58dba45
--- /dev/null
+++ b/tests/integration_tests.rs
@@ -0,0 +1,194 @@
+use assert_cmd::assert::OutputAssertExt;
+use assert_cmd::cargo::CommandCargoExt;
+use predicates::prelude::*;
+use std::fs;
+use std::process::Command;
+use tempfile::TempDir;
+
+#[test]
+fn test_help_flag() {
+    let mut cmd = Command::cargo_bin("ntu").unwrap();
+    cmd.arg("--help");
+    cmd.assert()
+        .success()
+        .stdout(predicate::str::contains("Usage: ntu"));
+}
+
+#[test]
+fn test_version_flag() {
+    let mut cmd = Command::cargo_bin("ntu").unwrap();
+    cmd.arg("--version");
+    cmd.assert()
+        .success()
+        .stdout(predicate::str::contains("NameToUnix"));
+}
+
+#[test]
+fn test_dry_run_no_changes() {
+    let temp_dir = TempDir::new().unwrap();
+    let file_path = temp_dir.path().join("test file.txt");
+    fs::write(&file_path, "test content").unwrap();
+
+    let mut cmd = Command::cargo_bin("ntu").unwrap();
+    cmd.arg("--dry-run").arg(temp_dir.path());
+    cmd.assert().success();
+
+    // File should still have spaces (not renamed)
+    assert!(file_path.exists());
+    assert!(!temp_dir.path().join("test_file.txt").exists());
+}
+
+#[test]
+fn test_actual_rename() {
+    let temp_dir = TempDir::new().unwrap();
+    let file_path = temp_dir.path().join("test file.txt");
+    fs::write(&file_path, "test content").unwrap();
+
+    let mut cmd = Command::cargo_bin("ntu").unwrap();
+    cmd.arg(temp_dir.path());
+    cmd.assert().success();
+
+    // File should be renamed
+    assert!(!file_path.exists());
+    assert!(temp_dir.path().join("test_file.txt").exists());
+}
+
+#[test]
+fn test_hidden_files_preserved() {
+    let temp_dir = TempDir::new().unwrap();
+    let file_path = temp_dir.path().join(".gitignore");
+    fs::write(&file_path, "*.tmp").unwrap();
+
+    let mut cmd = Command::cargo_bin("ntu").unwrap();
+    cmd.arg(temp_dir.path());
+    cmd.assert().success();
+
+    // Hidden file should not be renamed
+    assert!(file_path.exists());
+}
+
+#[test]
+fn test_hidden_file_with_spaces() {
+    let temp_dir = TempDir::new().unwrap();
+    let file_path = temp_dir.path().join(".my config");
+    fs::write(&file_path, "config content").unwrap();
+
+    let mut cmd = Command::cargo_bin("ntu").unwrap();
+    cmd.arg(temp_dir.path());
+    cmd.assert().success();
+
+    // Hidden file should be renamed but keep leading dot
+    assert!(!file_path.exists());
+    assert!(temp_dir.path().join(".my_config").exists());
+}
+
+#[test]
+fn test_umlaut_conversion() {
+    let temp_dir = TempDir::new().unwrap();
+    let file_path = temp_dir.path().join("Müller.txt");
+    fs::write(&file_path, "test").unwrap();
+
+    let mut cmd = Command::cargo_bin("ntu").unwrap();
+    cmd.arg(temp_dir.path());
+    cmd.assert().success();
+
+    // Umlaut should be converted
+    assert!(!file_path.exists());
+    assert!(temp_dir.path().join("Mueller.txt").exists());
+}
+
+#[test]
+fn test_double_extension() {
+    let temp_dir = TempDir::new().unwrap();
+    let file_path = temp_dir.path().join("my archive.tar.gz");
+    fs::write(&file_path, "archive").unwrap();
+
+    let mut cmd = Command::cargo_bin("ntu").unwrap();
+    cmd.arg(temp_dir.path());
+    cmd.assert().success();
+
+    // Should keep .tar.gz intact
+    assert!(!file_path.exists());
+    assert!(temp_dir.path().join("my_archive.tar.gz").exists());
+}
+
+#[test]
+fn test_exclude_pattern() {
+    let temp_dir = TempDir::new().unwrap();
+    let file1 = temp_dir.path().join("test file.txt");
+    let file2 = temp_dir.path().join("test file.tmp");
+    fs::write(&file1, "test1").unwrap();
+    fs::write(&file2, "test2").unwrap();
+
+    let mut cmd = Command::cargo_bin("ntu").unwrap();
+    cmd.arg("--exclude")
+        .arg("*.tmp")
+        .arg(temp_dir.path());
+    cmd.assert().success();
+
+    // .txt should be renamed, .tmp should not
+    assert!(!file1.exists());
+    assert!(temp_dir.path().join("test_file.txt").exists());
+    assert!(file2.exists()); // Excluded
+}
+
+#[test]
+fn test_quiet_mode() {
+    let temp_dir = TempDir::new().unwrap();
+    let file_path = temp_dir.path().join("test file.txt");
+    fs::write(&file_path, "test").unwrap();
+
+    let mut cmd = Command::cargo_bin("ntu").unwrap();
+    cmd.arg("--quiet").arg(temp_dir.path());
+    cmd.assert()
+        .success()
+        .stdout(predicate::str::is_empty());
+}
+
+#[test]
+fn test_multiple_paths() {
+    let temp_dir1 = TempDir::new().unwrap();
+    let temp_dir2 = TempDir::new().unwrap();
+    let file1 = temp_dir1.path().join("file 1.txt");
+    let file2 = temp_dir2.path().join("file 2.txt");
+    fs::write(&file1, "test1").unwrap();
+    fs::write(&file2, "test2").unwrap();
+
+    let mut cmd = Command::cargo_bin("ntu").unwrap();
+    cmd.arg(temp_dir1.path()).arg(temp_dir2.path());
+    cmd.assert().success();
+
+    // Both files should be renamed
+    assert!(temp_dir1.path().join("file_1.txt").exists());
+    assert!(temp_dir2.path().join("file_2.txt").exists());
+}
+
+#[test]
+fn test_parentheses_removed() {
+    let temp_dir = TempDir::new().unwrap();
+    let file_path = temp_dir.path().join("Document (1).txt");
+    fs::write(&file_path, "test").unwrap();
+
+    let mut cmd = Command::cargo_bin("ntu").unwrap();
+    cmd.arg(temp_dir.path());
+    cmd.assert().success();
+
+    // Parentheses should be replaced with underscores
+    assert!(!file_path.exists());
+    assert!(temp_dir.path().join("Document_1.txt").exists());
+}
+
+#[test]
+fn test_special_identifiers_preserved() {
+    let temp_dir = TempDir::new().unwrap();
+    let file_path = temp_dir.path().join("C++ Guide.pdf");
+    fs::write(&file_path, "test").unwrap();
+
+    let mut cmd = Command::cargo_bin("ntu").unwrap();
+    cmd.arg(temp_dir.path());
+    cmd.assert().success();
+
+    // C++ should be preserved
+    assert!(!file_path.exists());
+    assert!(temp_dir.path().join("C++_Guide.pdf").exists());
+}