diff --git a/pymkv/MKVFile.py b/pymkv/MKVFile.py
index 8de3221..fd1bd20 100644
--- a/pymkv/MKVFile.py
+++ b/pymkv/MKVFile.py
@@ -435,7 +435,7 @@ def add_attachment(self, attachment: str | MKVAttachment) -> None:
             msg = "Attachment is not str of MKVAttachment"
             raise TypeError(msg)
 
-    def get_track(self, track_num: int | None = None) -> MKVTrack:
+    def get_track(self, track_num: int | None = None) -> MKVTrack | list[MKVTrack]:
         """Get a :class:`~pymkv.MKVTrack` from the :class:`~pymkv.MKVFile` object.
 
         Parameters
diff --git a/pymkv/Timestamp.py b/pymkv/Timestamp.py
index 96a0af5..bf9dedd 100644
--- a/pymkv/Timestamp.py
+++ b/pymkv/Timestamp.py
@@ -1,6 +1,6 @@
 from __future__ import annotations
 
-from re import match
+import re
 
 
 class Timestamp:
@@ -175,7 +175,7 @@ def __getitem__(self, index: int) -> int:
     def ts(self) -> str:
         """Generates the timestamp specified in the object."""
         # parse timestamp format
-        format_groups = match(r"^(([Hh]{1,2}):)?([Mm]{1,2}):([Ss]{1,2})(\.([Nn]{1,9}))?$", self.form).groups()
+        format_groups = re.match(r"^(([Hh]{1,2}):)?([Mm]{1,2}):([Ss]{1,2})(\.([Nn]{1,9}))?$", self.form).groups()
         timestamp_format = [format_groups[i] is not None for i in (1, 2, 3, 5)]
 
         # create timestamp string
@@ -248,16 +248,16 @@ def form(self, form: str) -> None:
         self._form = form
 
     @staticmethod
-    def verify(timestamp: str | int) -> bool:
+    def verify(timestamp: str) -> bool:
         """Verify a timestamp has the proper form to be used in mkvmerge.
 
-        timestamp (str, int):
+        timestamp (str):
             The timestamp to be verified.
         """
         if not isinstance(timestamp, str):
             msg = f'"{type(timestamp)}" is not str type'
             raise TypeError(msg)
-        elif match(r"^[0-9]{1,2}(:[0-9]{1,2}){1,2}(\.[0-9]{1,9})?$", timestamp):  # noqa: RET506
+        elif re.match(r"^[0-9]{1,2}(:[0-9]{1,2}){1,2}(\.[0-9]{1,9})?$", timestamp):  # noqa: RET506
             return True
         return False
 
@@ -305,7 +305,7 @@ def splitting_timestamp(self, timestamp: str) -> None:
         The seconds (self.ss) will be set to 56.
         The nanoseconds (self.nn) will be set to 789012345.
         """
-        timestamp_groups = match(r"^(([0-9]{1,2}):)?([0-9]{1,2}):([0-9]{1,2})(\.([0-9]{1,9}))?$", timestamp).groups()
+        timestamp_groups = re.match(r"^(([0-9]{1,2}):)?([0-9]{1,2}):([0-9]{1,2})(\.([0-9]{1,9}))?$", timestamp).groups()
 
         timestamp = [timestamp_groups[i] for i in (1, 2, 3, 4)]
         timestamp_clean = []
diff --git a/tests/conftest.py b/tests/conftest.py
index 7bbb098..70b6aa7 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -21,7 +21,14 @@ def get_path_test_file_two(get_base_path: Path) -> Path:
 @pytest.fixture(autouse=True)
 def cleanup_mkv_files(get_base_path: Path, get_path_test_file: Path, get_path_test_file_two: Path) -> None:  # noqa: PT004
     yield
-    for ext in ["*.mkv", "*.mp4", "*.ogg"]:
+    for ext in ["*.mkv", "*.mp4", "*.ogg", "*.txt"]:
         for file_path in get_base_path.glob(ext):
             if file_path not in (get_path_test_file, get_path_test_file_two):
                 file_path.unlink()
+
+
+@pytest.fixture()
+def temp_file(tmp_path: Path) -> str:
+    file = tmp_path / "test_attachment.txt"
+    file.write_text("Test content")
+    return str(file)
diff --git a/tests/test_actions_track.py b/tests/test_actions_track.py
index b21da67..cec296f 100644
--- a/tests/test_actions_track.py
+++ b/tests/test_actions_track.py
@@ -66,3 +66,120 @@ def test_move_track_front_and_mux(get_base_path: Path, get_path_test_file: Path)
     assert len(mkv.tracks) == 2  # noqa: PLR2004
     assert mkv.tracks[0].track_type == "audio"
     assert mkv.tracks[1].track_type == "video"
+
+
+def test_mux_and_test_title(get_base_path: Path, get_path_test_file: Path) -> None:
+    output_file = get_base_path / "file-test.mkv"
+
+    mkv = MKVFile(get_path_test_file)
+    mkv.title = "Test title in mkv file"
+    mkv.mux(output_file)
+
+    mkv = MKVFile(output_file)
+
+    assert mkv.title == "Test title in mkv file"
+
+
+def test_mux_and_test_track_name(get_base_path: Path, get_path_test_file: Path) -> None:
+    output_file = get_base_path / "file-test.mkv"
+
+    mkv = MKVFile(get_path_test_file)
+    mkv.tracks[0].track_name = "Test track name"
+    mkv.mux(output_file)
+
+    mkv = MKVFile(output_file)
+
+    assert mkv.tracks[0].track_name == "Test track name"
+
+
+def test_move_track_end_raises(get_path_test_file: Path) -> None:
+    mkv = MKVFile(get_path_test_file)
+
+    with pytest.raises(IndexError):
+        mkv.move_track_end(-1)
+
+    with pytest.raises(IndexError):
+        mkv.move_track_end(2)
+
+
+def test_move_track_end_and_mux(get_base_path: Path, get_path_test_file: Path) -> None:
+    output_file = get_base_path / "file-test.mkv"
+
+    mkv = MKVFile(get_path_test_file)
+    mkv.move_track_end(0)
+    mkv.mux(output_file)
+
+    mkv = MKVFile(output_file)
+
+    assert len(mkv.tracks) == 2  # noqa: PLR2004
+    assert mkv.tracks[0].track_type == "audio"
+    assert mkv.tracks[1].track_type == "video"
+
+
+def test_move_track_forward_raises(get_path_test_file: Path) -> None:
+    mkv = MKVFile(get_path_test_file)
+
+    with pytest.raises(IndexError):
+        mkv.move_track_forward(-1)
+
+    with pytest.raises(IndexError):
+        mkv.move_track_forward(2)
+
+    with pytest.raises(IndexError):
+        mkv.move_track_forward(1)
+
+
+def test_move_track_forward_and_mux(get_base_path: Path, get_path_test_file: Path) -> None:
+    output_file = get_base_path / "file-test.mkv"
+
+    mkv = MKVFile(get_path_test_file)
+    mkv.move_track_forward(0)
+    mkv.mux(output_file)
+
+    mkv = MKVFile(output_file)
+
+    assert len(mkv.tracks) == 2  # noqa: PLR2004
+    assert mkv.tracks[0].track_type == "audio"
+    assert mkv.tracks[1].track_type == "video"
+
+
+def test_move_track_backward_raises(get_path_test_file: Path) -> None:
+    mkv = MKVFile(get_path_test_file)
+
+    with pytest.raises(IndexError):
+        mkv.move_track_backward(-1)
+
+    with pytest.raises(IndexError):
+        mkv.move_track_backward(2)
+
+
+def test_move_track_backward_and_mux(get_base_path: Path, get_path_test_file: Path) -> None:
+    output_file = get_base_path / "file-test.mkv"
+
+    mkv = MKVFile(get_path_test_file)
+    mkv.move_track_backward(1)
+    mkv.mux(output_file)
+
+    mkv = MKVFile(output_file)
+
+    assert len(mkv.tracks) == 2  # noqa: PLR2004
+    assert mkv.tracks[0].track_type == "audio"
+    assert mkv.tracks[1].track_type == "video"
+
+
+def test_get_track(get_path_test_file: Path) -> None:
+    mkv = MKVFile(get_path_test_file)
+    track = mkv.get_track(1)
+
+    assert track.track_type == "audio"
+
+    tracks = mkv.get_track()
+
+    assert isinstance(tracks, list)
+    assert len(tracks) == 2  # noqa: PLR2004
+
+
+def test_get_track_error(get_path_test_file: Path) -> None:
+    mkv = MKVFile(get_path_test_file)
+    with pytest.raises(IndexError):
+        mkv.get_track(2)
diff --git a/tests/test_add_file.py b/tests/test_add_file.py
index b976858..9168139 100644
--- a/tests/test_add_file.py
+++ b/tests/test_add_file.py
@@ -12,6 +12,12 @@ def test_add_file(get_base_path: Path, get_path_test_file: Path, get_path_test_f
     mkv_two = MKVFile(get_path_test_file_two)
     mkv.add_file(mkv_two)
 
+    for i, track in enumerate(mkv.tracks):
+        expected_file_id = i // 2  # the file_id should change every two tracks
+        expected_track_id = i % 2  # the track_id should alternate between 0 and 1
+        assert track.file_id == expected_file_id
+        assert track.track_id == expected_track_id
+
     assert len(mkv.tracks) == 4  # noqa: PLR2004
     mkv.mux(output_file)
 
diff --git a/tests/test_mkv_attachment.py b/tests/test_mkv_attachment.py
new file mode 100644
index 0000000..465c2f3
--- /dev/null
+++ b/tests/test_mkv_attachment.py
@@ -0,0 +1,74 @@
+from pathlib import Path
+
+import pytest
+
+from pymkv.MKVAttachment import MKVAttachment
+
+
+def test_init(temp_file: str) -> None:
+    attachment = MKVAttachment(temp_file)
+    assert attachment.file_path == temp_file
+    assert attachment.mime_type == "text/plain"
+    assert attachment.name is None
+    assert attachment.description is None
+    assert attachment.attach_once is False
+
+
+def test_init_with_options(temp_file: str) -> None:
+    attachment = MKVAttachment(temp_file, name="Test", description="Test Description", attach_once=True)
+    assert attachment.file_path == temp_file
+    assert attachment.name == "Test"
+    assert attachment.description == "Test Description"
+    assert attachment.attach_once is True
+
+
+def test_file_path_setter_valid(temp_file: str) -> None:
+    attachment = MKVAttachment(temp_file)
+    new_file = Path(temp_file).parent / "new_file.txt"
+    new_file.write_text("New content")
+    attachment.file_path = str(new_file)
+    assert attachment.file_path == str(new_file)
+    assert attachment.mime_type == "text/plain"
+    assert attachment.name is None
+
+
+def test_file_path_setter_invalid() -> None:
+    with pytest.raises(FileNotFoundError):
+        MKVAttachment("non_existent_file.txt")
+
+
+def test_repr(temp_file: str) -> None:
+    attachment = MKVAttachment(temp_file, name="Test", description="Test Description")
+    repr_str = repr(attachment)
+    assert "file_path" in repr_str
+    assert "name" in repr_str
+    assert "description" in repr_str
+    assert "mime_type" in repr_str
+
+
+def test_mime_type_guess(tmp_path: Path) -> None:
+    # Test different file types
+    file_types = {
+        "test.txt": "text/plain",
+        "test.jpg": "image/jpeg",
+        "test.png": "image/png",
+        "test.mp3": "audio/mpeg",
+    }
+
+    for file_name, expected_mime in file_types.items():
+        file_path = tmp_path / file_name
+        file_path.write_text("Test content")
+        attachment = MKVAttachment(str(file_path))
+        assert attachment.mime_type == expected_mime
+
+
+def test_file_path_expansion(tmp_path: Path, monkeypatch) -> None:  # noqa: ANN001
+    fake_home = tmp_path / "fake_home"
+    fake_home.mkdir()
+    monkeypatch.setenv("HOME", str(fake_home))
+
+    test_file = fake_home / "test_file.txt"
+    test_file.write_text("Test content")
+
+    attachment = MKVAttachment("~/test_file.txt")
+    assert attachment.file_path == str(test_file)
diff --git a/tests/test_open_files.py b/tests/test_open_files.py
index 9ed99d7..7475dbc 100644
--- a/tests/test_open_files.py
+++ b/tests/test_open_files.py
@@ -8,6 +8,7 @@
 def test_open_file(get_path_test_file: Path) -> None:
     mkv = MKVFile(get_path_test_file)
 
+    assert mkv.title is None
     assert len(mkv.tracks) == 2  # noqa: PLR2004
 
 
@@ -45,3 +46,11 @@ def test_empty_mkv_file() -> None:
 
     assert mkv.title == "test"
     assert len(mkv.tracks) == 0
+
+
+def test_verify_mkvmerge_in_mkv_file() -> None:
+    with pytest.raises(
+        FileNotFoundError,
+        match="mkvmerge is not at the specified path, add it there or changed mkvmerge_path property",
+    ):
+        MKVFile(title="test", mkvmerge_path="mkvmerge_test")
diff --git a/tests/test_timestamp.py b/tests/test_timestamp.py
new file mode 100644
index 0000000..0be9a87
--- /dev/null
+++ b/tests/test_timestamp.py
@@ -0,0 +1,91 @@
+import pytest
+
+from pymkv.Timestamp import Timestamp
+
+
+def test_init() -> None:
+    ts1 = Timestamp("01:23:45.678")
+    assert str(ts1) == "01:23:45.678"
+
+    ts2 = Timestamp(3661)  # 1 hour, 1 minute, 1 second
+    assert str(ts2) == "01:01:01"
+
+    ts3 = Timestamp(hh=2, mm=30, ss=15, nn=500000000)
+    assert str(ts3) == "02:30:15.5"
+
+
+def test_comparison() -> None:
+    ts1 = Timestamp("01:00:00")
+    ts2 = Timestamp("02:00:00")
+    ts3 = Timestamp("01:00:00")
+
+    assert ts1 < ts2
+    assert ts2 > ts1
+    assert ts1 <= ts3
+    assert ts1 >= ts3
+    assert ts1 == ts3
+    assert ts1 != ts2
+
+
+def test_properties() -> None:
+    ts = Timestamp("12:34:56.789")
+    assert ts.hh == 12  # noqa: PLR2004
+    assert ts.mm == 34  # noqa: PLR2004
+    assert ts.ss == 56  # noqa: PLR2004
+    assert ts.nn == 789000000  # noqa: PLR2004
+
+
+def test_setters() -> None:
+    ts = Timestamp()
+    ts.hh = 10
+    ts.mm = 20
+    ts.ss = 30
+    ts.nn = 400000000
+    assert str(ts) == "10:20:30.4"
+
+    # Test overflow handling
+    ts.mm = 70
+    assert ts.mm == 0
+
+
+def test_verify() -> None:
+    assert Timestamp.verify("01:23:45")
+    assert Timestamp.verify("01:23:45.678")
+    assert not Timestamp.verify("25.00:00")
+
+
+def test_extract() -> None:
+    ts = Timestamp()
+    ts.extract(3661)  # 1 hour, 1 minute, 1 second
+
+    assert ts.hh == 1
+    assert ts.mm == 1
+    assert ts.ss == 1
+    assert ts.nn == 0
+
+
+def test_getitem() -> None:
+    ts = Timestamp("01:23:45.678")
+    assert ts[0] == 1  # hours
+    assert ts[1] == 23  # minutes  # noqa: PLR2004
+    assert ts[2] == 45  # seconds  # noqa: PLR2004
+    assert ts[3] == 45  # seconds (again, as per the implementation)  # noqa: PLR2004
+
+
+def test_invalid_input() -> None:
+    with pytest.raises(TypeError):
+        Timestamp([])  # Invalid type
+
+    with pytest.raises(ValueError):  # noqa: PT011
+        Timestamp("invalid_timestamp")
+
+
+def test_ts_property() -> None:
+    ts = Timestamp("01:23:45.678")
+    assert ts.ts == "01:23:45.678"
+
+    ts.ts = "02:30:00"
+    assert ts.ts == "02:30:00"
+
+    with pytest.raises(TypeError):
+        ts.ts = []  # Invalid type