diff --git a/tests/test_library.py b/tests/test_library.py
index e37b771..cc35233 100755
--- a/tests/test_library.py
+++ b/tests/test_library.py
@@ -16,7 +16,7 @@ class TestPyLastLibrary(TestPyLastWithLastFm):
         representation = repr(library)
 
         # Assert
-        self.assert_startswith(representation, "pylast.Library(")
+        assert representation.startswith("pylast.Library(")
 
     def test_str(self) -> None:
         # Arrange
@@ -26,7 +26,7 @@ class TestPyLastLibrary(TestPyLastWithLastFm):
         string = str(library)
 
         # Assert
-        self.assert_endswith(string, "'s Library")
+        assert string.endswith("'s Library")
 
     def test_library_is_hashable(self) -> None:
         # Arrange
diff --git a/tests/test_librefm.py b/tests/test_librefm.py
index 0647976..01c43d9 100755
--- a/tests/test_librefm.py
+++ b/tests/test_librefm.py
@@ -6,11 +6,11 @@ from flaky import flaky
 
 import pylast
 
-from .test_pylast import PyLastTestCase, load_secrets
+from .test_pylast import load_secrets
 
 
 @flaky(max_runs=3, min_passes=1)
-class TestPyLastWithLibreFm(PyLastTestCase):
+class TestPyLastWithLibreFm:
     """Own class for Libre.fm because we don't need the Last.fm setUp"""
 
     def test_libre_fm(self) -> None:
@@ -38,4 +38,4 @@ class TestPyLastWithLibreFm(PyLastTestCase):
         representation = repr(network)
 
         # Assert
-        self.assert_startswith(representation, "pylast.LibreFMNetwork(")
+        assert representation.startswith("pylast.LibreFMNetwork(")
diff --git a/tests/test_network.py b/tests/test_network.py
index d10cc66..51f0b18 100755
--- a/tests/test_network.py
+++ b/tests/test_network.py
@@ -330,12 +330,12 @@ class TestPyLastNetwork(TestPyLastWithLastFm):
         # Assert
         assert len(images) == 4
 
-        self.assert_startswith(images[pylast.SIZE_SMALL], "https://")
-        self.assert_endswith(images[pylast.SIZE_SMALL], ".png")
+        assert images[pylast.SIZE_SMALL].startswith("https://")
+        assert images[pylast.SIZE_SMALL].endswith(".png")
         assert "/34s/" in images[pylast.SIZE_SMALL]
 
-        self.assert_startswith(images[pylast.SIZE_EXTRA_LARGE], "https://")
-        self.assert_endswith(images[pylast.SIZE_EXTRA_LARGE], ".png")
+        assert images[pylast.SIZE_EXTRA_LARGE].startswith("https://")
+        assert images[pylast.SIZE_EXTRA_LARGE].endswith(".png")
         assert "/300x300/" in images[pylast.SIZE_EXTRA_LARGE]
 
     def test_artist_search(self) -> None:
@@ -362,12 +362,12 @@ class TestPyLastNetwork(TestPyLastWithLastFm):
         # Assert
         assert len(images) == 5
 
-        self.assert_startswith(images[pylast.SIZE_SMALL], "https://")
-        self.assert_endswith(images[pylast.SIZE_SMALL], ".png")
+        assert images[pylast.SIZE_SMALL].startswith("https://")
+        assert images[pylast.SIZE_SMALL].endswith(".png")
         assert "/34s/" in images[pylast.SIZE_SMALL]
 
-        self.assert_startswith(images[pylast.SIZE_EXTRA_LARGE], "https://")
-        self.assert_endswith(images[pylast.SIZE_EXTRA_LARGE], ".png")
+        assert images[pylast.SIZE_EXTRA_LARGE].startswith("https://")
+        assert images[pylast.SIZE_EXTRA_LARGE].endswith(".png")
         assert "/300x300/" in images[pylast.SIZE_EXTRA_LARGE]
 
     def test_track_search(self) -> None:
@@ -396,12 +396,12 @@ class TestPyLastNetwork(TestPyLastWithLastFm):
         # Assert
         assert len(images) == 4
 
-        self.assert_startswith(images[pylast.SIZE_SMALL], "https://")
-        self.assert_endswith(images[pylast.SIZE_SMALL], ".png")
+        assert images[pylast.SIZE_SMALL].startswith("https://")
+        assert images[pylast.SIZE_SMALL].endswith(".png")
         assert "/34s/" in images[pylast.SIZE_SMALL]
 
-        self.assert_startswith(images[pylast.SIZE_EXTRA_LARGE], "https://")
-        self.assert_endswith(images[pylast.SIZE_EXTRA_LARGE], ".png")
+        assert images[pylast.SIZE_EXTRA_LARGE].startswith("https://")
+        assert images[pylast.SIZE_EXTRA_LARGE].endswith(".png")
         assert "/300x300/" in images[pylast.SIZE_EXTRA_LARGE]
 
     def test_search_get_total_result_count(self) -> None:
diff --git a/tests/test_pylast.py b/tests/test_pylast.py
index cdaf50e..2c3c7c7 100755
--- a/tests/test_pylast.py
+++ b/tests/test_pylast.py
@@ -32,21 +32,13 @@ def load_secrets():  # pragma: no cover
     return doc
 
 
-class PyLastTestCase:
-    def assert_startswith(self, s, prefix, start=None, end=None) -> None:
-        assert s.startswith(prefix, start, end)
-
-    def assert_endswith(self, s, suffix, start=None, end=None) -> None:
-        assert s.endswith(suffix, start, end)
-
-
 def _no_xfail_rerun_filter(err, name, test, plugin) -> bool:
     for _ in test.iter_markers(name="xfail"):
         return False
 
 
 @flaky(max_runs=3, min_passes=1, rerun_filter=_no_xfail_rerun_filter)
-class TestPyLastWithLastFm(PyLastTestCase):
+class TestPyLastWithLastFm:
     secrets = None
 
     def unix_timestamp(self):
diff --git a/tests/test_user.py b/tests/test_user.py
index 6e0f3ba..12308eb 100755
--- a/tests/test_user.py
+++ b/tests/test_user.py
@@ -24,7 +24,7 @@ class TestPyLastUser(TestPyLastWithLastFm):
         representation = repr(user)
 
         # Assert
-        self.assert_startswith(representation, "pylast.User('RJ',")
+        assert representation.startswith("pylast.User('RJ',")
 
     def test_str(self) -> None:
         # Arrange
@@ -345,7 +345,7 @@ class TestPyLastUser(TestPyLastWithLastFm):
         url = user.get_image()
 
         # Assert
-        self.assert_startswith(url, "https://")
+        assert url.startswith("https://")
 
     def test_user_get_library(self) -> None:
         # Arrange
@@ -428,8 +428,8 @@ class TestPyLastUser(TestPyLastWithLastFm):
         image = user.get_image()
 
         # Assert
-        self.assert_startswith(image, "https://")
-        self.assert_endswith(image, ".png")
+        assert image.startswith("https://")
+        assert image.endswith(".png")
 
     def test_get_url(self) -> None:
         # Arrange