diff --git a/tests/test_utils.py b/tests/test_utils.py
index e1bbac4b..a2ba2c8e 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -8,20 +8,109 @@ from zoneinfo import ZoneInfo
 
 import time_machine
 
-from ffplayout.utils import get_date, playlist
+from ..ffplayout.utils import (gen_dummy, gen_filler, get_date, get_delta,
+                               get_float, is_advertisement, loop_input,
+                               playlist, pre, seek_in, set_length,
+                               src_or_dummy, str_to_sec)
 
 # set time zone
 _TZ = ZoneInfo("Europe/Berlin")
-# fake date and time
-SOURCE_TIME = [2021, 5, 26, 0, 0, 0]
 
 
-@time_machine.travel(datetime.datetime(*SOURCE_TIME, tzinfo=_TZ))
+def test_str_to_sec():
+    assert str_to_sec('06:00:00') == 21600
+
+
+@time_machine.travel(datetime.datetime(*[2021, 5, 26, 15, 30, 5], tzinfo=_TZ))
+def test_get_delta():
+    playlist.start = 0
+    current, total = get_delta(15 * 3600 + 30 * 60 + 1)
+    assert current == -4
+    assert total == 8 * 3600 + 29 * 60 + 55
+
+
+@time_machine.travel(datetime.datetime(*[2021, 5, 26, 0, 0, 0], tzinfo=_TZ))
 def test_playlist_start_zero():
     playlist.start = 0
-    assert get_date(False, (24*60*60) + 1) == '2021-05-27'
-    assert get_date(False, (24*60*60) - 1) == '2021-05-26'
+    assert get_date(False, 24 * 60 * 60 + 1) == '2021-05-27'
+    assert get_date(False, 24 * 60 * 60 - 1) == '2021-05-26'
 
 
-if __name__ == '__main__':
-    test_playlist_start_zero()
+@time_machine.travel(datetime.datetime(*[2021, 5, 26, 5, 59, 59], tzinfo=_TZ))
+def test_playlist_start_six_before():
+    playlist.start = 6 * 60 * 60
+    assert get_date(True) == '2021-05-25'
+    assert get_date(False) == '2021-05-26'
+
+
+@time_machine.travel(datetime.datetime(*[2021, 5, 26, 6, 0, 0], tzinfo=_TZ))
+def test_playlist_start_six_after():
+    playlist.start = 6 * 60 * 60
+    assert get_date(False) == '2021-05-26'
+
+
+def test_get_float():
+    assert get_float('5') == 5
+    assert get_float('5', None) == 5.0
+    assert get_float('5a', None) is None
+
+
+def test_is_advertisement():
+    assert is_advertisement({'category': 'advertisement'}) is True
+    assert is_advertisement({'category': ''}) is False
+    assert is_advertisement({}) is False
+
+
+def test_seek_in():
+    assert seek_in(10) == ['-ss', '10']
+    assert seek_in(0) == []
+
+
+def test_set_length():
+    assert set_length(300, 50, 200) == ['-t', '150']
+    assert set_length(300, 0, 300) == []
+
+
+def test_loop_input():
+    assert loop_input('/store/file.mp4', 300, 450) == ['-stream_loop', '2',
+                                                       '-i', '/store/file.mp4',
+                                                       '-t', '450']
+
+
+def test_gen_dummy():
+    pre.w = 1024
+    pre.h = 576
+    pre.fps = 25
+    assert gen_dummy(30) == ['-f', 'lavfi', '-i',
+                             'color=c=#121212:s=1024x576:d=30:r=25,'
+                             'format=pix_fmts=yuv420p', '-f', 'lavfi',
+                             '-i', 'anoisesrc=d=30:c=pink:r=48000:a=0.05']
+
+
+def test_gen_filler():
+    source = gen_filler({'source': '/store/file.mp4',
+                         'in': 0, 'out': 300, 'duration': 300, 'seek': 0})
+    filler = {'duration': 300, 'in': 0, 'out': 300, 'seek': 0,
+              'source': '/tv-media/ADtv/01 - Intro/seperator.clock.5-00.mp4',
+              'src_cmd': [
+                  '-i', '/tv-media/ADtv/01 - Intro/seperator.clock.5-00.mp4',
+                  '-t', '300']}
+
+    source.pop('probe')
+
+    assert source == filler
+
+
+def test_src_or_dummy():
+    source = src_or_dummy({'source': '/store/file.mp4',
+                           'in': 0, 'out': 300, 'duration': 300, 'seek': 0})
+
+    dummy = {'duration': 300, 'in': 0, 'out': 300, 'seek': 0,
+             'source': '/tv-media/ADtv/01 - Intro/seperator.clock.5-00.mp4',
+             'src_cmd': [
+                '-i', '/tv-media/ADtv/01 - Intro/seperator.clock.5-00.mp4',
+                '-t', '300']}
+
+    source.pop('probe')
+
+    assert source == dummy