diff --git a/.appveyor.yml b/.appveyor.yml
index e300d19..57be9e6 100644
--- a/.appveyor.yml
+++ b/.appveyor.yml
@@ -14,7 +14,7 @@ install:
   - conda config --set always_yes yes --set changeps1 no
   - conda update -q conda
   - conda info -a
-  - conda create -q -n test-environment --channel=conda-forge mmtf-python numpy scipy pandas pytest looseversion python=%PYTHON_VERSION%
+  - conda create -q -n test-environment --channel=conda-forge mmtf-python numpy scipy pandas pytest looseversion importlib_resources python=%PYTHON_VERSION%
   - activate test-environment
 
 test_script:
diff --git a/.github/workflows/publish.yaml b/.github/workflows/publish.yaml
index b43841a..926e674 100644
--- a/.github/workflows/publish.yaml
+++ b/.github/workflows/publish.yaml
@@ -5,7 +5,7 @@ name: Publish BioPandas to PyPI / GitHub
 
 on:
   pull_request:
-    branches: [ main ]
+    branches: [main]
 
 jobs:
   test-style:
@@ -13,42 +13,42 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v3
+      - uses: actions/checkout@v3
 
-    - name: Set up Python
-      uses: actions/setup-python@v4
-      with:
-        python-version: '3.x'
-        cache: 'pip'
+      - name: Set up Python
+        uses: actions/setup-python@v4
+        with:
+          python-version: "3.x"
+          cache: "pip"
 
-    - name: Install package dependencies for testing
-      run: pip install .[test]
+      - name: Install package dependencies for testing
+        run: pip install .[test]
 
-    - name: Run all the pytest tests
-      run: flake8 ./biopandas
+      - name: Run all the pytest tests
+        run: flake8 ./biopandas
 
   test-pytest:
     name: Run pytest tests
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v3
+      - uses: actions/checkout@v3
 
-    - name: Set up Python
-      uses: actions/setup-python@v4
-      with:
-        python-version: '3.x'
-        cache: 'pip'
+      - name: Set up Python
+        uses: actions/setup-python@v4
+        with:
+          python-version: "3.x"
+          cache: "pip"
 
-    - name: Install package dependencies for testing
-      run: pip install .[test]
+      - name: Install package dependencies for testing
+        run: pip install .[test]
 
-    - name: Run all the pytest tests
-      run: pytest ./biopandas -sv
+      - name: Run all the pytest tests
+        run: pytest -sv
 
   build-n-publish:
     needs: [test-pytest] # only runs if tests are passing
-    if: startsWith(github.ref, 'refs/tags/v')  # Check if the tag starts with 'v'
+    if: startsWith(github.ref, 'refs/tags/v') # Check if the tag starts with 'v'
     name: Build and publish to PyPI
     runs-on: ubuntu-latest
 
diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index 1439afa..56db5e0 100755
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -8,6 +8,7 @@ The CHANGELOG for the current development version is available at
 
 - Feature: added method to `PandasMmcif` that allow to select by model ids. PR #[145](https://github.com/BioPandas/biopandas/pull/145))
 - Dev: switched testing framework entirely to pytest. Drops nose dependency due to version conflicts with Python 3.12 (`nose`) and 3.8 (`nose`) PR #[146](https://github.com/BioPandas/biopandas/pull/146))
+-  Avoid inclusion of test scripts and test data in the PyPI release of the Biopandas library. PR #[148](https://github.com/BioPandas/biopandas/pull/148). Addresses issue [#147](https://github.com/BioPandas/biopandas/issues/147)
 
 
 ### 0.5.0dev1 (31/7/2023)
diff --git a/biopandas/mmcif/tests/__init__.py b/tests/__init__.py
similarity index 100%
rename from biopandas/mmcif/tests/__init__.py
rename to tests/__init__.py
diff --git a/biopandas/mmtf/tests/__init__.py b/tests/mmcif/__init__.py
similarity index 100%
rename from biopandas/mmtf/tests/__init__.py
rename to tests/mmcif/__init__.py
diff --git a/biopandas/mmcif/tests/data/1ehz.cif b/tests/mmcif/data/1ehz.cif
similarity index 100%
rename from biopandas/mmcif/tests/data/1ehz.cif
rename to tests/mmcif/data/1ehz.cif
diff --git a/biopandas/mmcif/tests/data/1t48.cif b/tests/mmcif/data/1t48.cif
similarity index 100%
rename from biopandas/mmcif/tests/data/1t48.cif
rename to tests/mmcif/data/1t48.cif
diff --git a/biopandas/mmcif/tests/data/1t49.cif b/tests/mmcif/data/1t49.cif
similarity index 100%
rename from biopandas/mmcif/tests/data/1t49.cif
rename to tests/mmcif/data/1t49.cif
diff --git a/biopandas/mmcif/tests/data/2d7t.cif b/tests/mmcif/data/2d7t.cif
similarity index 100%
rename from biopandas/mmcif/tests/data/2d7t.cif
rename to tests/mmcif/data/2d7t.cif
diff --git a/biopandas/mmcif/tests/data/2jyf.cif.gz b/tests/mmcif/data/2jyf.cif.gz
similarity index 100%
rename from biopandas/mmcif/tests/data/2jyf.cif.gz
rename to tests/mmcif/data/2jyf.cif.gz
diff --git a/biopandas/mmcif/tests/data/3eiy.cif b/tests/mmcif/data/3eiy.cif
similarity index 100%
rename from biopandas/mmcif/tests/data/3eiy.cif
rename to tests/mmcif/data/3eiy.cif
diff --git a/biopandas/mmcif/tests/data/3eiy.cif.gz b/tests/mmcif/data/3eiy.cif.gz
similarity index 100%
rename from biopandas/mmcif/tests/data/3eiy.cif.gz
rename to tests/mmcif/data/3eiy.cif.gz
diff --git a/biopandas/mmcif/tests/data/3eiy_stripped_ele.cif b/tests/mmcif/data/3eiy_stripped_ele.cif
similarity index 100%
rename from biopandas/mmcif/tests/data/3eiy_stripped_ele.cif
rename to tests/mmcif/data/3eiy_stripped_ele.cif
diff --git a/biopandas/mmcif/tests/data/4eiy.cif b/tests/mmcif/data/4eiy.cif
similarity index 100%
rename from biopandas/mmcif/tests/data/4eiy.cif
rename to tests/mmcif/data/4eiy.cif
diff --git a/biopandas/mmcif/tests/data/5mtn_multichain.cif b/tests/mmcif/data/5mtn_multichain.cif
similarity index 100%
rename from biopandas/mmcif/tests/data/5mtn_multichain.cif
rename to tests/mmcif/data/5mtn_multichain.cif
diff --git a/biopandas/mmcif/tests/data/AF-Q5VSL9-F1-model_v2.cif b/tests/mmcif/data/AF-Q5VSL9-F1-model_v2.cif
similarity index 100%
rename from biopandas/mmcif/tests/data/AF-Q5VSL9-F1-model_v2.cif
rename to tests/mmcif/data/AF-Q5VSL9-F1-model_v2.cif
diff --git a/biopandas/mmcif/tests/data/AF-Q5VSL9-F1-model_v3.cif b/tests/mmcif/data/AF-Q5VSL9-F1-model_v3.cif
similarity index 100%
rename from biopandas/mmcif/tests/data/AF-Q5VSL9-F1-model_v3.cif
rename to tests/mmcif/data/AF-Q5VSL9-F1-model_v3.cif
diff --git a/biopandas/mmcif/tests/data/AF-Q5VSL9-F1-model_v4.cif b/tests/mmcif/data/AF-Q5VSL9-F1-model_v4.cif
similarity index 100%
rename from biopandas/mmcif/tests/data/AF-Q5VSL9-F1-model_v4.cif
rename to tests/mmcif/data/AF-Q5VSL9-F1-model_v4.cif
diff --git a/biopandas/mmcif/tests/test_amino3to1.py b/tests/mmcif/test_amino3to1.py
similarity index 96%
rename from biopandas/mmcif/tests/test_amino3to1.py
rename to tests/mmcif/test_amino3to1.py
index 83a671c..1effebe 100644
--- a/biopandas/mmcif/tests/test_amino3to1.py
+++ b/tests/mmcif/test_amino3to1.py
@@ -4,14 +4,23 @@
 # Project Website: http://rasbt.github.io/biopandas/
 # Code Repository: https://github.com/rasbt/biopandas
 
-import os
+import sys
+
+if sys.version_info >= (3, 9):
+    import importlib.resources as pkg_resources
+else:
+    import importlib_resources as pkg_resources
 
 import numpy as np
+
+import tests.mmcif.data
 from biopandas.mmcif import PandasMmcif
 
+TEST_DATA = pkg_resources.files(tests.mmcif.data)
+
 
 def test_defaults():
-    TESTDATA_1t48 = os.path.join(os.path.dirname(__file__), "data", "1t48.cif")
+    TESTDATA_1t48 = str(TEST_DATA.joinpath("1t48.cif"))
     p1t48 = PandasMmcif()
     p1t48.read_mmcif(TESTDATA_1t48)
     expect_res = [
@@ -309,7 +318,7 @@ def test_defaults():
 
 
 def test_sameindex():
-    TESTDATA_1t48 = os.path.join(os.path.dirname(__file__), "data", "1t48.cif")
+    TESTDATA_1t48 = str(TEST_DATA.joinpath("1t48.cif"))
     p1t48 = PandasMmcif()
     p1t48.read_mmcif(TESTDATA_1t48)
     p1t48.df["ATOM"].index = np.zeros(p1t48.df["ATOM"].shape[0], dtype=int)
@@ -608,9 +617,7 @@ def test_sameindex():
 
 
 def test_multichain():
-    TESTDATA_5mtn = os.path.join(
-        os.path.dirname(__file__), "data", "5mtn_multichain.cif"
-    )
+    TESTDATA_5mtn = str(TEST_DATA.joinpath("5mtn_multichain.cif"))
     mtn = PandasMmcif()
     mtn.read_mmcif(TESTDATA_5mtn)
     expect_res_a = [
@@ -818,7 +825,7 @@ def test_multichain():
 
 
 def test_pdb_with_insertion_codes():
-    PDB_2D7T_PATH = os.path.join(os.path.dirname(__file__), "data", "2d7t.cif")
+    PDB_2D7T_PATH = str(TEST_DATA.joinpath("2d7t.cif"))
 
     ppdb = PandasMmcif().read_mmcif(PDB_2D7T_PATH)
     sequence = ppdb.amino3to1()
diff --git a/biopandas/mmcif/tests/test_assign_df.py b/tests/mmcif/test_assign_df.py
similarity index 67%
rename from biopandas/mmcif/tests/test_assign_df.py
rename to tests/mmcif/test_assign_df.py
index 2706637..b012d60 100644
--- a/biopandas/mmcif/tests/test_assign_df.py
+++ b/tests/mmcif/test_assign_df.py
@@ -4,16 +4,22 @@
 # Project Website: http://rasbt.github.io/biopandas/
 # Code Repository: https://github.com/rasbt/biopandas
 
-import os
+import sys
 
+if sys.version_info >= (3, 9):
+    import importlib.resources as pkg_resources
+else:
+    import importlib_resources as pkg_resources
+
+import tests.mmcif.data
 from biopandas.mmcif import PandasMmcif
-from biopandas.testutils import assert_raises
+from tests.testutils import assert_raises
 
-TESTDATA_FILENAME = os.path.join(os.path.dirname(__file__), "data", "3eiy.cif")
+TEST_DATA = pkg_resources.files(tests.mmcif.data)
 
 
 def test_overwrite_df():
-    data_path = os.path.join(os.path.dirname(__file__), "data", "3eiy.cif")
+    data_path = str(TEST_DATA.joinpath("3eiy.cif"))
     pdb = PandasMmcif().read_mmcif(data_path)
 
     def overwrite():
diff --git a/biopandas/mmcif/tests/test_distance.py b/tests/mmcif/test_distance.py
similarity index 77%
rename from biopandas/mmcif/tests/test_distance.py
rename to tests/mmcif/test_distance.py
index e7cd116..df45be9 100644
--- a/biopandas/mmcif/tests/test_distance.py
+++ b/tests/mmcif/test_distance.py
@@ -4,14 +4,23 @@
 # Project Website: http://rasbt.github.io/biopandas/
 # Code Repository: https://github.com/rasbt/biopandas
 
-import os
+import sys
+
+if sys.version_info >= (3, 9):
+    import importlib.resources as pkg_resources
+else:
+    import importlib_resources as pkg_resources
 
 import pandas as pd
+
+import tests.mmcif.data
 from biopandas.mmcif import PandasMmcif
 
+TEST_DATA = pkg_resources.files(tests.mmcif.data)
+
 
 def test_equal():
-    TESTDATA_1t48 = os.path.join(os.path.dirname(__file__), "data", "1t48.cif")
+    TESTDATA_1t48 = str(TEST_DATA.joinpath("1t48.cif"))
 
     p1t48 = PandasMmcif()
     p1t48.read_mmcif(TESTDATA_1t48)
@@ -25,7 +34,7 @@ def test_equal():
 
 
 def test_deprecated_str_arg():
-    TESTDATA_1t48 = os.path.join(os.path.dirname(__file__), "data", "1t48.cif")
+    TESTDATA_1t48 = str(TEST_DATA.joinpath("1t48.cif"))
 
     p1t48 = PandasMmcif()
     p1t48.read_mmcif(TESTDATA_1t48)
@@ -39,7 +48,7 @@ def test_deprecated_str_arg():
 
 
 def test_use_external_df():
-    TESTDATA_1t48 = os.path.join(os.path.dirname(__file__), "data", "1t48.cif")
+    TESTDATA_1t48 = str(TEST_DATA.joinpath("1t48.cif"))
 
     p1t48 = PandasMmcif()
     p1t48.read_mmcif(TESTDATA_1t48)
diff --git a/biopandas/mmcif/tests/test_multiple_models.py b/tests/mmcif/test_multiple_models.py
similarity index 63%
rename from biopandas/mmcif/tests/test_multiple_models.py
rename to tests/mmcif/test_multiple_models.py
index e8cf496..084fd15 100644
--- a/biopandas/mmcif/tests/test_multiple_models.py
+++ b/tests/mmcif/test_multiple_models.py
@@ -4,22 +4,35 @@
 # License: BSD 3 clause
 # Project Website: http://rasbt.github.io/biopandas/
 # Code Repository: https://github.com/rasbt/biopandas
-import os
+import sys
 
+if sys.version_info >= (3, 9):
+    import importlib.resources as pkg_resources
+else:
+    import importlib_resources as pkg_resources
+
+import tests.mmcif.data
 from biopandas.mmcif import PandasMmcif
 
-TESTDATA_FILENAME = os.path.join(os.path.dirname(__file__), "data", "2jyf.cif.gz")
+TEST_DATA = pkg_resources.files(tests.mmcif.data)
+
+TESTDATA_FILENAME = str(TEST_DATA.joinpath("2jyf.cif.gz"))
+
 
 def test_label_models():
     biopandas_structure = PandasMmcif().read_mmcif(TESTDATA_FILENAME)
     biopandas_structure.label_models()
     assert "model_id" in biopandas_structure.df["ATOM"].columns
 
+
 def test_get_model():
     biopandas_structure = PandasMmcif().read_mmcif(TESTDATA_FILENAME)
     MODEL_INDEX = 1
     new_biopandas_structure = biopandas_structure.get_model(MODEL_INDEX)
-    assert new_biopandas_structure.df["ATOM"]["pdbx_PDB_model_num"].all() == MODEL_INDEX
+    assert (
+        new_biopandas_structure.df["ATOM"]["pdbx_PDB_model_num"].all()
+        == MODEL_INDEX
+    )
 
 
 def test_get_models():
@@ -27,4 +40,7 @@ def test_get_models():
     MODEL_INDICES = [1, 3, 5]
 
     new_biopandas_structure = biopandas_structure.get_models(MODEL_INDICES)
-    assert new_biopandas_structure.df["ATOM"]["pdbx_PDB_model_num"].all() in MODEL_INDICES
\ No newline at end of file
+    assert (
+        new_biopandas_structure.df["ATOM"]["pdbx_PDB_model_num"].all()
+        in MODEL_INDICES
+    )
diff --git a/biopandas/mmcif/tests/test_read_mmcif.py b/tests/mmcif/test_read_mmcif.py
similarity index 93%
rename from biopandas/mmcif/tests/test_read_mmcif.py
rename to tests/mmcif/test_read_mmcif.py
index bfba806..e2a907b 100644
--- a/biopandas/mmcif/tests/test_read_mmcif.py
+++ b/tests/mmcif/test_read_mmcif.py
@@ -5,36 +5,35 @@
 # Code Repository: https://github.com/rasbt/biopandas
 
 
-import os
+import sys
+
+if sys.version_info >= (3, 9):
+    import importlib.resources as pkg_resources
+else:
+    import importlib_resources as pkg_resources
 from pathlib import Path
 from urllib.error import HTTPError
 
 import pandas as pd
 import pytest
+from pandas.testing import assert_frame_equal
+
+import tests.mmcif.data
 from biopandas.mmcif import PandasMmcif
 from biopandas.pdb import PandasPdb
-from biopandas.testutils import assert_raises
-from pandas.testing import assert_frame_equal
+from tests.testutils import assert_raises
+
+TEST_DATA = pkg_resources.files(tests.mmcif.data)
 
-TESTDATA_FILENAME = os.path.join(os.path.dirname(__file__), "data", "3eiy.cif")
+TESTDATA_FILENAME = str(TEST_DATA.joinpath("3eiy.cif"))
 
 # Not clear on how ANISOU records are handled in mmCIF files so skipping
-# TESTDATA_FILENAME2 = os.path.join(
-#    os.path.dirname(__file__), "data", "4eiy_anisouchunk.cif"
-# )
-TESTDATA_FILENAME2 = os.path.join(
-    os.path.dirname(__file__), "data", "4eiy.cif"
-)
-TESTDATA_FILENAME_GZ = os.path.join(
-    os.path.dirname(__file__), "data", "3eiy.cif.gz"
-)
-
-TESTDATA_FILENAME_AF2_V4 = os.path.join(
-    os.path.dirname(__file__), "data", "AF-Q5VSL9-F1-model_v4.cif"
-)
-TESTDATA_FILENAME_AF2_V3 = os.path.join(
-    os.path.dirname(__file__), "data", "AF-Q5VSL9-F1-model_v3.cif"
-)
+# TESTDATA_FILENAME2 = str(TEST_DATA.joinpath("4eiy_anisouchunk.cif"))
+TESTDATA_FILENAME2 = str(TEST_DATA.joinpath("4eiy.cif"))
+TESTDATA_FILENAME_GZ = str(TEST_DATA.joinpath("3eiy.cif.gz"))
+
+TESTDATA_FILENAME_AF2_V4 = str(TEST_DATA.joinpath("AF-Q5VSL9-F1-model_v4.cif"))
+TESTDATA_FILENAME_AF2_V3 = str(TEST_DATA.joinpath("AF-Q5VSL9-F1-model_v3.cif"))
 
 ATOM_DF_COLUMNS = [
     "B_iso_or_equiv",
diff --git a/biopandas/mmcif/tests/test_rmsd.py b/tests/mmcif/test_rmsd.py
similarity index 77%
rename from biopandas/mmcif/tests/test_rmsd.py
rename to tests/mmcif/test_rmsd.py
index 054f3b2..0c21bbf 100644
--- a/biopandas/mmcif/tests/test_rmsd.py
+++ b/tests/mmcif/test_rmsd.py
@@ -4,17 +4,26 @@
 # Project Website: http://rasbt.github.io/biopandas/
 # Code Repository: https://github.com/rasbt/biopandas
 
-import os
+import sys
+
+if sys.version_info >= (3, 9):
+    import importlib.resources as pkg_resources
+else:
+    import importlib_resources as pkg_resources
 
 import pytest
+
+import tests.mmcif.data
 from biopandas.mmcif import PandasMmcif
 
-TESTDATA_1t48 = os.path.join(os.path.dirname(__file__), "data", "1t48.cif")
-TESTDATA_1t49 = os.path.join(os.path.dirname(__file__), "data", "1t49.cif")
-# TESTDATA_lig1 = os.path.join(os.path.dirname(__file__), "data", "lig_conf_1.pdb")
-# TESTDATA_lig2 = os.path.join(os.path.dirname(__file__), "data", "lig_conf_2.pdb")
+TEST_DATA = pkg_resources.files(tests.mmcif.data)
+
+TESTDATA_1t48 = str(TEST_DATA.joinpath("1t48.cif"))
+TESTDATA_1t49 = str(TEST_DATA.joinpath("1t49.cif"))
+# TESTDATA_lig1 = str(TEST_DATA.joinpath("lig_conf_1.pdb"))
+# TESTDATA_lig2 = str(TEST_DATA.joinpath("lig_conf_2.pdb"))
 
-TESTDATA_rna = os.path.join(os.path.dirname(__file__), "data", "1ehz.cif")
+TESTDATA_rna = str(TEST_DATA.joinpath("1ehz.cif"))
 
 p1t48 = PandasMmcif()
 p1t48.read_mmcif(TESTDATA_1t48)
diff --git a/biopandas/pdb/tests/__init__.py b/tests/mmtf/__init__.py
similarity index 100%
rename from biopandas/pdb/tests/__init__.py
rename to tests/mmtf/__init__.py
diff --git a/biopandas/mmtf/tests/data/1ehz.mmtf b/tests/mmtf/data/1ehz.mmtf
similarity index 100%
rename from biopandas/mmtf/tests/data/1ehz.mmtf
rename to tests/mmtf/data/1ehz.mmtf
diff --git a/biopandas/mmtf/tests/data/1t48.mmtf b/tests/mmtf/data/1t48.mmtf
similarity index 100%
rename from biopandas/mmtf/tests/data/1t48.mmtf
rename to tests/mmtf/data/1t48.mmtf
diff --git a/biopandas/mmtf/tests/data/1t49.mmtf b/tests/mmtf/data/1t49.mmtf
similarity index 100%
rename from biopandas/mmtf/tests/data/1t49.mmtf
rename to tests/mmtf/data/1t49.mmtf
diff --git a/biopandas/mmtf/tests/data/2d7t.mmtf b/tests/mmtf/data/2d7t.mmtf
similarity index 100%
rename from biopandas/mmtf/tests/data/2d7t.mmtf
rename to tests/mmtf/data/2d7t.mmtf
diff --git a/biopandas/mmtf/tests/data/2jyf.mmtf b/tests/mmtf/data/2jyf.mmtf
similarity index 100%
rename from biopandas/mmtf/tests/data/2jyf.mmtf
rename to tests/mmtf/data/2jyf.mmtf
diff --git a/biopandas/mmtf/tests/data/3eiy.mmtf b/tests/mmtf/data/3eiy.mmtf
similarity index 100%
rename from biopandas/mmtf/tests/data/3eiy.mmtf
rename to tests/mmtf/data/3eiy.mmtf
diff --git a/biopandas/mmtf/tests/data/3eiy.mmtf.gz b/tests/mmtf/data/3eiy.mmtf.gz
similarity index 100%
rename from biopandas/mmtf/tests/data/3eiy.mmtf.gz
rename to tests/mmtf/data/3eiy.mmtf.gz
diff --git a/biopandas/mmtf/tests/data/4CUP.mmtf b/tests/mmtf/data/4CUP.mmtf
similarity index 100%
rename from biopandas/mmtf/tests/data/4CUP.mmtf
rename to tests/mmtf/data/4CUP.mmtf
diff --git a/biopandas/mmtf/tests/data/4eiy.mmtf b/tests/mmtf/data/4eiy.mmtf
similarity index 100%
rename from biopandas/mmtf/tests/data/4eiy.mmtf
rename to tests/mmtf/data/4eiy.mmtf
diff --git a/biopandas/mmtf/tests/data/5mtn.mmtf b/tests/mmtf/data/5mtn.mmtf
similarity index 100%
rename from biopandas/mmtf/tests/data/5mtn.mmtf
rename to tests/mmtf/data/5mtn.mmtf
diff --git a/biopandas/mmtf/tests/test_amino3to1.py b/tests/mmtf/test_amino3to1.py
similarity index 96%
rename from biopandas/mmtf/tests/test_amino3to1.py
rename to tests/mmtf/test_amino3to1.py
index 081265f..ea0c51f 100644
--- a/biopandas/mmtf/tests/test_amino3to1.py
+++ b/tests/mmtf/test_amino3to1.py
@@ -4,16 +4,23 @@
 # Project Website: http://rasbt.github.io/biopandas/
 # Code Repository: https://github.com/rasbt/biopandas
 
-import os
+import sys
+
+if sys.version_info >= (3, 9):
+    import importlib.resources as pkg_resources
+else:
+    import importlib_resources as pkg_resources
 
 import numpy as np
+
+import tests.mmtf.data
 from biopandas.mmtf import PandasMmtf
 
+TEST_DATA = pkg_resources.files(tests.mmtf.data)
+
 
 def test_defaults():
-    TESTDATA_1t48 = os.path.join(
-        os.path.dirname(__file__), "data", "1t48.mmtf"
-    )
+    TESTDATA_1t48 = str(TEST_DATA.joinpath("1t48.mmtf"))
     p1t48 = PandasMmtf()
     p1t48.read_mmtf(TESTDATA_1t48)
     expect_res = [
@@ -321,9 +328,7 @@ def test_defaults():
 
 
 def test_sameindex():
-    TESTDATA_1t48 = os.path.join(
-        os.path.dirname(__file__), "data", "1t48.mmtf"
-    )
+    TESTDATA_1t48 = str(TEST_DATA.joinpath("1t48.mmtf"))
     p1t48 = PandasMmtf()
     p1t48.read_mmtf(TESTDATA_1t48)
     p1t48.df["ATOM"].index = np.zeros(p1t48.df["ATOM"].shape[0], dtype=int)
@@ -632,9 +637,7 @@ def test_sameindex():
 
 
 def test_multichain():
-    TESTDATA_5mtn = os.path.join(
-        os.path.dirname(__file__), "data", "5mtn.mmtf"
-    )
+    TESTDATA_5mtn = str(TEST_DATA.joinpath("5mtn.mmtf"))
     mtn = PandasMmtf()
     mtn.read_mmtf(TESTDATA_5mtn)
     expect_res_a = [
@@ -842,9 +845,7 @@ def test_multichain():
 
 
 def test_pdb_with_insertion_codes():
-    PDB_2D7T_PATH = os.path.join(
-        os.path.dirname(__file__), "data", "2d7t.mmtf"
-    )
+    PDB_2D7T_PATH = str(TEST_DATA.joinpath("2d7t.mmtf"))
 
     ppdb = PandasMmtf().read_mmtf(PDB_2D7T_PATH)
     sequence = ppdb.amino3to1()
diff --git a/biopandas/mmtf/tests/test_assign_df.py b/tests/mmtf/test_assign_df.py
similarity index 61%
rename from biopandas/mmtf/tests/test_assign_df.py
rename to tests/mmtf/test_assign_df.py
index f9dd1bd..72d2363 100644
--- a/biopandas/mmtf/tests/test_assign_df.py
+++ b/tests/mmtf/test_assign_df.py
@@ -4,19 +4,24 @@
 # Project Website: http://rasbt.github.io/biopandas/
 # Code Repository: https://github.com/rasbt/biopandas
 
-import os
+import sys
 
+if sys.version_info >= (3, 9):
+    import importlib.resources as pkg_resources
+else:
+    import importlib_resources as pkg_resources
+
+import tests.mmtf.data
 from biopandas.mmtf import PandasMmtf
-from biopandas.testutils import assert_raises
+from tests.testutils import assert_raises
+
+TEST_DATA = pkg_resources.files(tests.mmtf.data)
 
-TESTDATA_FILENAME = os.path.join(
-    os.path.dirname(__file__), "data", "3eiy.mmtf"
-)
+TESTDATA_FILENAME = str(TEST_DATA.joinpath("3eiy.mmtf"))
 
 
 def test_overwrite_df():
-    data_path = os.path.join(os.path.dirname(__file__), "data", "3eiy.mmtf")
-    pdb = PandasMmtf().read_mmtf(data_path)
+    pdb = PandasMmtf().read_mmtf(TESTDATA_FILENAME)
 
     def overwrite():
         pdb.df = "bla"
diff --git a/biopandas/mmtf/tests/test_distance.py b/tests/mmtf/test_distance.py
similarity index 77%
rename from biopandas/mmtf/tests/test_distance.py
rename to tests/mmtf/test_distance.py
index 96291e3..856feff 100644
--- a/biopandas/mmtf/tests/test_distance.py
+++ b/tests/mmtf/test_distance.py
@@ -4,16 +4,23 @@
 # Project Website: http://rasbt.github.io/biopandas/
 # Code Repository: https://github.com/rasbt/biopandas
 
-import os
+import sys
+
+if sys.version_info >= (3, 9):
+    import importlib.resources as pkg_resources
+else:
+    import importlib_resources as pkg_resources
 
 import pandas as pd
+
+import tests.mmtf.data
 from biopandas.mmtf import PandasMmtf
 
+TEST_DATA = pkg_resources.files(tests.mmtf.data)
+
 
 def test_equal():
-    TESTDATA_1t48 = os.path.join(
-        os.path.dirname(__file__), "data", "1t48.mmtf"
-    )
+    TESTDATA_1t48 = str(TEST_DATA.joinpath("1t48.mmtf"))
 
     p1t48 = PandasMmtf()
     p1t48.read_mmtf(TESTDATA_1t48)
@@ -27,9 +34,7 @@ def test_equal():
 
 
 def test_deprecated_str_arg():
-    TESTDATA_1t48 = os.path.join(
-        os.path.dirname(__file__), "data", "1t48.mmtf"
-    )
+    TESTDATA_1t48 = str(TEST_DATA.joinpath("1t48.mmtf"))
 
     p1t48 = PandasMmtf()
     p1t48.read_mmtf(TESTDATA_1t48)
@@ -43,9 +48,7 @@ def test_deprecated_str_arg():
 
 
 def test_use_external_df():
-    TESTDATA_1t48 = os.path.join(
-        os.path.dirname(__file__), "data", "1t48.mmtf"
-    )
+    TESTDATA_1t48 = str(TEST_DATA.joinpath("1t48.mmtf"))
 
     p1t48 = PandasMmtf()
     p1t48.read_mmtf(TESTDATA_1t48)
diff --git a/biopandas/mmtf/tests/test_multiple_models.py b/tests/mmtf/test_multiple_models.py
similarity index 83%
rename from biopandas/mmtf/tests/test_multiple_models.py
rename to tests/mmtf/test_multiple_models.py
index 30be1cc..55ed818 100644
--- a/biopandas/mmtf/tests/test_multiple_models.py
+++ b/tests/mmtf/test_multiple_models.py
@@ -4,14 +4,23 @@
 # License: BSD 3 clause
 # Project Website: http://rasbt.github.io/biopandas/
 # Code Repository: https://github.com/rasbt/biopandas
+
+import sys
+
+if sys.version_info >= (3, 9):
+    import importlib.resources as pkg_resources
+else:
+    import importlib_resources as pkg_resources
 import os
 
-from biopandas.mmtf import PandasMmtf
 from pandas.testing import assert_frame_equal
 
-TESTDATA_FILENAME = os.path.join(
-    os.path.dirname(__file__), "data", "2jyf.mmtf"
-)
+import tests.mmtf.data
+from biopandas.mmtf import PandasMmtf
+
+TEST_DATA = pkg_resources.files(tests.mmtf.data)
+
+TESTDATA_FILENAME = str(TEST_DATA.joinpath("2jyf.mmtf"))
 
 
 def test_label_models():
diff --git a/biopandas/mmtf/tests/test_read_mmtf.py b/tests/mmtf/test_read_mmtf.py
similarity index 80%
rename from biopandas/mmtf/tests/test_read_mmtf.py
rename to tests/mmtf/test_read_mmtf.py
index 045ff1d..cba1b73 100644
--- a/biopandas/mmtf/tests/test_read_mmtf.py
+++ b/tests/mmtf/test_read_mmtf.py
@@ -4,32 +4,29 @@
 # Project Website: http://rasbt.github.io/biopandas/
 # Code Repository: https://github.com/rasbt/biopandas
 
-import os
+import sys
+
+if sys.version_info >= (3, 9):
+    import importlib.resources as pkg_resources
+else:
+    import importlib_resources as pkg_resources
 import unittest
 
 import pandas as pd
+
+import tests.mmtf.data
+import tests.pdb.data
 from biopandas.mmtf import PandasMmtf
 from biopandas.pdb import PandasPdb
 
-MMTF_TESTDATA_FILENAME = os.path.join(
-    os.path.dirname(__file__), "data", "3eiy.mmtf"
-)
-MMTF_TESTDATA_FILENAME_GZ = os.path.join(
-    os.path.dirname(__file__), "data", "3eiy.mmtf.gz"
-)
-
-PDB_TESTDATA_FILENAME = os.path.join(
-    os.path.dirname(__file__), "..", "..", "pdb", "tests", "data", "3eiy.pdb"
-)
-PDB_TESTDATA_FILENAME_GZ = os.path.join(
-    os.path.dirname(__file__),
-    "..",
-    "..",
-    "pdb",
-    "tests",
-    "data",
-    "3eiy.pdb.gz",
-)
+TEST_DATA = pkg_resources.files(tests.mmtf.data)
+PDB_TEST_DATA = pkg_resources.files(tests.pdb.data)
+
+MMTF_TESTDATA_FILENAME = str(TEST_DATA.joinpath("3eiy.mmtf"))
+MMTF_TESTDATA_FILENAME_GZ = str(TEST_DATA.joinpath("3eiy.mmtf.gz"))
+
+PDB_TESTDATA_FILENAME = str(PDB_TEST_DATA.joinpath("3eiy.pdb"))
+PDB_TESTDATA_FILENAME_GZ = str(PDB_TEST_DATA.joinpath("3eiy.pdb.gz"))
 
 
 ATOM_DF_COLUMNS = [
diff --git a/biopandas/mmtf/tests/test_rmsd.py b/tests/mmtf/test_rmsd.py
similarity index 80%
rename from biopandas/mmtf/tests/test_rmsd.py
rename to tests/mmtf/test_rmsd.py
index 1131009..32538af 100644
--- a/biopandas/mmtf/tests/test_rmsd.py
+++ b/tests/mmtf/test_rmsd.py
@@ -4,17 +4,26 @@
 # Project Website: http://rasbt.github.io/biopandas/
 # Code Repository: https://github.com/rasbt/biopandas
 
-import os
+import sys
+
+if sys.version_info >= (3, 9):
+    import importlib.resources as pkg_resources
+else:
+    import importlib_resources as pkg_resources
 
 import pytest
+
+import tests.mmtf.data
 from biopandas.mmtf import PandasMmtf
 
-TESTDATA_1t48 = os.path.join(os.path.dirname(__file__), "data", "1t48.mmtf")
-TESTDATA_1t49 = os.path.join(os.path.dirname(__file__), "data", "1t49.mmtf")
-# TESTDATA_lig1 = os.path.join(os.path.dirname(__file__), "data", "lig_conf_1.pdb")
-# TESTDATA_lig2 = os.path.join(os.path.dirname(__file__), "data", "lig_conf_2.pdb")
+TEST_DATA = pkg_resources.files(tests.mmtf.data)
+
+TESTDATA_1t48 = str(TEST_DATA.joinpath("1t48.mmtf"))
+TESTDATA_1t49 = str(TEST_DATA.joinpath("1t49.mmtf"))
+# TESTDATA_lig1 = str(TEST_DATA.joinpath("lig_conf_1.pdb"))
+# TESTDATA_lig2 = str(TEST_DATA.joinpath("lig_conf_2.pdb"))
 
-TESTDATA_rna = os.path.join(os.path.dirname(__file__), "data", "1ehz.mmtf")
+TESTDATA_rna = str(TEST_DATA.joinpath("1ehz.mmtf"))
 
 p1t48 = PandasMmtf()
 p1t48.read_mmtf(TESTDATA_1t48)
diff --git a/biopandas/mmtf/tests/test_write_mmtf.py b/tests/mmtf/test_write_mmtf.py
similarity index 99%
rename from biopandas/mmtf/tests/test_write_mmtf.py
rename to tests/mmtf/test_write_mmtf.py
index 69452e8..f516f6c 100644
--- a/biopandas/mmtf/tests/test_write_mmtf.py
+++ b/tests/mmtf/test_write_mmtf.py
@@ -2,9 +2,10 @@
 import unittest
 
 import pandas as pd
-from biopandas.mmtf.pandas_mmtf import PandasMmtf, write_mmtf
 from pandas.testing import assert_frame_equal
 
+from biopandas.mmtf.pandas_mmtf import PandasMmtf, write_mmtf
+
 
 @unittest.skip(reason="PDB No longer serves MMTF files.")
 def test_write_mmtf_bp():
diff --git a/tests/mol2/__init__.py b/tests/mol2/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/biopandas/mol2/tests/data/1b5e_1.mol2 b/tests/mol2/data/1b5e_1.mol2
similarity index 100%
rename from biopandas/mol2/tests/data/1b5e_1.mol2
rename to tests/mol2/data/1b5e_1.mol2
diff --git a/biopandas/mol2/tests/data/1b5e_2.mol2 b/tests/mol2/data/1b5e_2.mol2
similarity index 100%
rename from biopandas/mol2/tests/data/1b5e_2.mol2
rename to tests/mol2/data/1b5e_2.mol2
diff --git a/biopandas/mol2/tests/data/40_mol2_files.mol2 b/tests/mol2/data/40_mol2_files.mol2
similarity index 100%
rename from biopandas/mol2/tests/data/40_mol2_files.mol2
rename to tests/mol2/data/40_mol2_files.mol2
diff --git a/biopandas/mol2/tests/data/40_mol2_files.mol2.gz b/tests/mol2/data/40_mol2_files.mol2.gz
similarity index 100%
rename from biopandas/mol2/tests/data/40_mol2_files.mol2.gz
rename to tests/mol2/data/40_mol2_files.mol2.gz
diff --git a/biopandas/mol2/tests/data/empty_line.mol2 b/tests/mol2/data/empty_line.mol2
similarity index 100%
rename from biopandas/mol2/tests/data/empty_line.mol2
rename to tests/mol2/data/empty_line.mol2
diff --git a/biopandas/mol2/tests/test_mol2_io.py b/tests/mol2/test_mol2_io.py
similarity index 66%
rename from biopandas/mol2/tests/test_mol2_io.py
rename to tests/mol2/test_mol2_io.py
index b6c4c98..5591829 100644
--- a/biopandas/mol2/tests/test_mol2_io.py
+++ b/tests/mol2/test_mol2_io.py
@@ -4,26 +4,29 @@
 # Project Website: http://rasbt.github.io/biopandas/
 # Code Repository: https://github.com/rasbt/biopandas
 
-import os
+import sys
 
+if sys.version_info >= (3, 9):
+    import importlib.resources as pkg_resources
+else:
+    import importlib_resources as pkg_resources
+
+import tests.mol2.data
 from biopandas.mol2.mol2_io import split_multimol2
-from biopandas.testutils import assert_raises
+from tests.testutils import assert_raises
 
-this_dir = os.path.dirname(os.path.realpath(__file__))
+TEST_DATA = pkg_resources.files(tests.mol2.data)
 
 
 def test_split_multimol2():
     all_mol2 = []
-    for i in split_multimol2(
-        os.path.join(this_dir, "data", "40_mol2_files.mol2")
-    ):
+    for i in split_multimol2(str(TEST_DATA.joinpath("40_mol2_files.mol2"))):
         all_mol2.append(i[0])
     assert all_mol2[1] == "ZINC04084113"
     assert len(all_mol2) == 40
 
 
 def test_split_multimol2_wrong_format():
-
     expect = (
         "Wrong file format;" "allowed file formats are .mol2 and .mol2.gz."
     )
@@ -36,9 +39,7 @@ def run_code():
 
 def test_split_multimol2_gz():
     all_mol2 = []
-    for i in split_multimol2(
-        os.path.join(this_dir, "data", "40_mol2_files.mol2.gz")
-    ):
+    for i in split_multimol2(str(TEST_DATA.joinpath("40_mol2_files.mol2.gz"))):
         all_mol2.append(i[0])
     assert all_mol2[1].decode() == "ZINC04084113"
     assert len(all_mol2) == 40
diff --git a/biopandas/mol2/tests/test_pandas_mol2.py b/tests/mol2/test_pandas_mol2.py
similarity index 74%
rename from biopandas/mol2/tests/test_pandas_mol2.py
rename to tests/mol2/test_pandas_mol2.py
index ba88dd0..b7b2867 100644
--- a/biopandas/mol2/tests/test_pandas_mol2.py
+++ b/tests/mol2/test_pandas_mol2.py
@@ -1,4 +1,4 @@
-""" Utility function for reading Tripos MOL2 files from files"""
+"""Utility function for reading Tripos MOL2 files from files"""
 
 # BioPandas
 # Author: Sebastian Raschka <mail@sebastianraschka.com>
@@ -6,20 +6,25 @@
 # Project Website: http://rasbt.github.io/biopandas/
 # Code Repository: https://github.com/rasbt/biopandas
 
-import os
+import sys
 
+if sys.version_info >= (3, 9):
+    import importlib.resources as pkg_resources
+else:
+    import importlib_resources as pkg_resources
+
+import tests.mol2.data
 from biopandas.mol2 import PandasMol2
 from biopandas.mol2.mol2_io import split_multimol2
-from biopandas.testutils import assert_raises
+from tests.testutils import assert_raises
 
-this_dir = os.path.dirname(os.path.realpath(__file__))
+TEST_DATA = pkg_resources.files(tests.mol2.data)
 
 
 def test_read_mol2():
-
-    data_path_1 = os.path.join(this_dir, "data", "40_mol2_files.mol2")
-    data_path_2 = os.path.join(this_dir, "data", "40_mol2_files.mol2.gz")
-    data_path_3 = os.path.join(this_dir, "data", "empty_line.mol2")
+    data_path_1 = str(TEST_DATA.joinpath("40_mol2_files.mol2"))
+    data_path_2 = str(TEST_DATA.joinpath("40_mol2_files.mol2.gz"))
+    data_path_3 = str(TEST_DATA.joinpath("empty_line.mol2"))
 
     for data_path in (data_path_1, data_path_2):
         pdmol = PandasMol2().read_mol2(data_path)
@@ -46,8 +51,7 @@ def test_read_mol2():
 
 
 def test_read_mol2_from_list():
-
-    data_path = os.path.join(this_dir, "data", "40_mol2_files.mol2")
+    data_path = str(TEST_DATA.joinpath("40_mol2_files.mol2"))
     mol2 = next(split_multimol2(data_path))
 
     pdmol = PandasMol2().read_mol2_from_list(
@@ -58,8 +62,8 @@ def test_read_mol2_from_list():
 
 
 def test_rmsd():
-    data_path_1 = os.path.join(this_dir, "data", "1b5e_1.mol2")
-    data_path_2 = os.path.join(this_dir, "data", "1b5e_2.mol2")
+    data_path_1 = str(TEST_DATA.joinpath("1b5e_1.mol2"))
+    data_path_2 = str(TEST_DATA.joinpath("1b5e_2.mol2"))
 
     pdmol_1 = PandasMol2().read_mol2(data_path_1)
     pdmol_2 = PandasMol2().read_mol2(data_path_2)
@@ -69,14 +73,14 @@ def test_rmsd():
 
 
 def test_distance():
-    data_path = os.path.join(this_dir, "data", "1b5e_1.mol2")
+    data_path = str(TEST_DATA.joinpath("1b5e_1.mol2"))
 
     pdmol = PandasMol2().read_mol2(data_path)
     assert round(pdmol.distance().values[0], 3) == 31.185
 
 
 def test_distance_external_df():
-    data_path = os.path.join(this_dir, "data", "1b5e_1.mol2")
+    data_path = str(TEST_DATA.joinpath("1b5e_1.mol2"))
 
     pdmol = PandasMol2().read_mol2(data_path)
     new_df = pdmol.df.iloc[1:, :].copy()
@@ -84,7 +88,7 @@ def test_distance_external_df():
 
 
 def test_overwrite_df():
-    data_path = os.path.join(this_dir, "data", "1b5e_1.mol2")
+    data_path = str(TEST_DATA.joinpath("1b5e_1.mol2"))
     pdmol = PandasMol2().read_mol2(data_path)
 
     def overwrite():
diff --git a/tests/pdb/__init__.py b/tests/pdb/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/biopandas/pdb/tests/data/1ehz-rna_short.pdb b/tests/pdb/data/1ehz-rna_short.pdb
similarity index 100%
rename from biopandas/pdb/tests/data/1ehz-rna_short.pdb
rename to tests/pdb/data/1ehz-rna_short.pdb
diff --git a/biopandas/pdb/tests/data/1t48_995.pdb b/tests/pdb/data/1t48_995.pdb
similarity index 100%
rename from biopandas/pdb/tests/data/1t48_995.pdb
rename to tests/pdb/data/1t48_995.pdb
diff --git a/biopandas/pdb/tests/data/1t49_995.pdb b/tests/pdb/data/1t49_995.pdb
similarity index 100%
rename from biopandas/pdb/tests/data/1t49_995.pdb
rename to tests/pdb/data/1t49_995.pdb
diff --git a/biopandas/pdb/tests/data/2d7t.pdb b/tests/pdb/data/2d7t.pdb
similarity index 100%
rename from biopandas/pdb/tests/data/2d7t.pdb
rename to tests/pdb/data/2d7t.pdb
diff --git a/biopandas/pdb/tests/data/2jyf.pdb b/tests/pdb/data/2jyf.pdb
similarity index 100%
rename from biopandas/pdb/tests/data/2jyf.pdb
rename to tests/pdb/data/2jyf.pdb
diff --git a/biopandas/pdb/tests/data/3eiy.pdb b/tests/pdb/data/3eiy.pdb
similarity index 100%
rename from biopandas/pdb/tests/data/3eiy.pdb
rename to tests/pdb/data/3eiy.pdb
diff --git a/biopandas/pdb/tests/data/3eiy.pdb.gz b/tests/pdb/data/3eiy.pdb.gz
similarity index 100%
rename from biopandas/pdb/tests/data/3eiy.pdb.gz
rename to tests/pdb/data/3eiy.pdb.gz
diff --git a/biopandas/pdb/tests/data/3eiy_stripped_no_ele.pdb b/tests/pdb/data/3eiy_stripped_no_ele.pdb
similarity index 100%
rename from biopandas/pdb/tests/data/3eiy_stripped_no_ele.pdb
rename to tests/pdb/data/3eiy_stripped_no_ele.pdb
diff --git a/biopandas/pdb/tests/data/4eiy_anisouchunk.pdb b/tests/pdb/data/4eiy_anisouchunk.pdb
similarity index 100%
rename from biopandas/pdb/tests/data/4eiy_anisouchunk.pdb
rename to tests/pdb/data/4eiy_anisouchunk.pdb
diff --git a/biopandas/pdb/tests/data/5mtn_multichain.pdb b/tests/pdb/data/5mtn_multichain.pdb
similarity index 100%
rename from biopandas/pdb/tests/data/5mtn_multichain.pdb
rename to tests/pdb/data/5mtn_multichain.pdb
diff --git a/biopandas/pdb/tests/data/AF-Q5VSL9-F1-model_v2.pdb b/tests/pdb/data/AF-Q5VSL9-F1-model_v2.pdb
similarity index 100%
rename from biopandas/pdb/tests/data/AF-Q5VSL9-F1-model_v2.pdb
rename to tests/pdb/data/AF-Q5VSL9-F1-model_v2.pdb
diff --git a/biopandas/pdb/tests/data/AF-Q5VSL9-F1-model_v3.pdb b/tests/pdb/data/AF-Q5VSL9-F1-model_v3.pdb
similarity index 100%
rename from biopandas/pdb/tests/data/AF-Q5VSL9-F1-model_v3.pdb
rename to tests/pdb/data/AF-Q5VSL9-F1-model_v3.pdb
diff --git a/biopandas/pdb/tests/data/AF-Q5VSL9-F1-model_v4.pdb b/tests/pdb/data/AF-Q5VSL9-F1-model_v4.pdb
similarity index 100%
rename from biopandas/pdb/tests/data/AF-Q5VSL9-F1-model_v4.pdb
rename to tests/pdb/data/AF-Q5VSL9-F1-model_v4.pdb
diff --git a/biopandas/pdb/tests/data/lig_conf_1.pdb b/tests/pdb/data/lig_conf_1.pdb
similarity index 100%
rename from biopandas/pdb/tests/data/lig_conf_1.pdb
rename to tests/pdb/data/lig_conf_1.pdb
diff --git a/biopandas/pdb/tests/data/lig_conf_2.pdb b/tests/pdb/data/lig_conf_2.pdb
similarity index 100%
rename from biopandas/pdb/tests/data/lig_conf_2.pdb
rename to tests/pdb/data/lig_conf_2.pdb
diff --git a/biopandas/pdb/tests/test_amino3to1.py b/tests/pdb/test_amino3to1.py
similarity index 94%
rename from biopandas/pdb/tests/test_amino3to1.py
rename to tests/pdb/test_amino3to1.py
index cabc9e4..276e2e3 100644
--- a/biopandas/pdb/tests/test_amino3to1.py
+++ b/tests/pdb/test_amino3to1.py
@@ -4,16 +4,23 @@
 # Project Website: http://rasbt.github.io/biopandas/
 # Code Repository: https://github.com/rasbt/biopandas
 
-import os
+import sys
+
+if sys.version_info >= (3, 9):
+    import importlib.resources as pkg_resources
+else:
+    import importlib_resources as pkg_resources
 
 import numpy as np
+
+import tests.pdb.data
 from biopandas.pdb import PandasPdb
 
+TEST_DATA = pkg_resources.files(tests.pdb.data)
+
 
 def test_defaults():
-    TESTDATA_1t48 = os.path.join(
-        os.path.dirname(__file__), "data", "1t48_995.pdb"
-    )
+    TESTDATA_1t48 = str(TEST_DATA.joinpath("1t48_995.pdb"))
     p1t48 = PandasPdb()
     p1t48.read_pdb(TESTDATA_1t48)
     expect_res = [
@@ -149,9 +156,7 @@ def test_defaults():
 
 
 def test_sameindex():
-    TESTDATA_1t48 = os.path.join(
-        os.path.dirname(__file__), "data", "1t48_995.pdb"
-    )
+    TESTDATA_1t48 = str(TEST_DATA.joinpath("1t48_995.pdb"))
     p1t48 = PandasPdb()
     p1t48.read_pdb(TESTDATA_1t48)
     print(p1t48)
@@ -290,9 +295,7 @@ def test_sameindex():
 
 
 def test_multichain():
-    TESTDATA_5mtn = os.path.join(
-        os.path.dirname(__file__), "data", "5mtn_multichain.pdb"
-    )
+    TESTDATA_5mtn = str(TEST_DATA.joinpath("5mtn_multichain.pdb"))
     mtn = PandasPdb()
     mtn.read_pdb(TESTDATA_5mtn)
     expect_res_a = [
@@ -500,8 +503,7 @@ def test_multichain():
 
 
 def test_pdb_with_insertion_codes():
-
-    PDB_2D7T_PATH = os.path.join(os.path.dirname(__file__), "data", "2d7t.pdb")
+    PDB_2D7T_PATH = str(TEST_DATA.joinpath("2d7t.pdb"))
 
     ppdb = PandasPdb().read_pdb(PDB_2D7T_PATH)
     sequence = ppdb.amino3to1()
diff --git a/biopandas/pdb/tests/test_assign_df.py b/tests/pdb/test_assign_df.py
similarity index 60%
rename from biopandas/pdb/tests/test_assign_df.py
rename to tests/pdb/test_assign_df.py
index f339609..84bb93c 100644
--- a/biopandas/pdb/tests/test_assign_df.py
+++ b/tests/pdb/test_assign_df.py
@@ -4,17 +4,24 @@
 # Project Website: http://rasbt.github.io/biopandas/
 # Code Repository: https://github.com/rasbt/biopandas
 
-import os
+import sys
 
+if sys.version_info >= (3, 9):
+    import importlib.resources as pkg_resources
+else:
+    import importlib_resources as pkg_resources
+
+import tests.pdb.data
 from biopandas.pdb import PandasPdb
-from biopandas.testutils import assert_raises
+from tests.testutils import assert_raises
+
+TEST_DATA = pkg_resources.files(tests.pdb.data)
 
-TESTDATA_FILENAME = os.path.join(os.path.dirname(__file__), "data", "3eiy.pdb")
+TESTDATA_FILENAME = str(TEST_DATA.joinpath("3eiy.pdb"))
 
 
 def test_overwrite_df():
-    data_path = os.path.join(os.path.dirname(__file__), "data", "3eiy.pdb")
-    pdb = PandasPdb().read_pdb(data_path)
+    pdb = PandasPdb().read_pdb(TESTDATA_FILENAME)
 
     def overwrite():
         pdb.df = "bla"
diff --git a/biopandas/pdb/tests/test_distance.py b/tests/pdb/test_distance.py
similarity index 76%
rename from biopandas/pdb/tests/test_distance.py
rename to tests/pdb/test_distance.py
index aec7f2e..4c92f2c 100644
--- a/biopandas/pdb/tests/test_distance.py
+++ b/tests/pdb/test_distance.py
@@ -4,16 +4,23 @@
 # Project Website: http://rasbt.github.io/biopandas/
 # Code Repository: https://github.com/rasbt/biopandas
 
-import os
+import sys
+
+if sys.version_info >= (3, 9):
+    import importlib.resources as pkg_resources
+else:
+    import importlib_resources as pkg_resources
 
 import pandas as pd
+
+import tests.pdb.data
 from biopandas.pdb import PandasPdb
 
+TEST_DATA = pkg_resources.files(tests.pdb.data)
+
 
 def test_equal():
-    TESTDATA_1t48 = os.path.join(
-        os.path.dirname(__file__), "data", "1t48_995.pdb"
-    )
+    TESTDATA_1t48 = str(TEST_DATA.joinpath("1t48_995.pdb"))
 
     p1t48 = PandasPdb()
     p1t48.read_pdb(TESTDATA_1t48)
@@ -27,9 +34,7 @@ def test_equal():
 
 
 def test_deprecated_str_arg():
-    TESTDATA_1t48 = os.path.join(
-        os.path.dirname(__file__), "data", "1t48_995.pdb"
-    )
+    TESTDATA_1t48 = str(TEST_DATA.joinpath("1t48_995.pdb"))
 
     p1t48 = PandasPdb()
     p1t48.read_pdb(TESTDATA_1t48)
@@ -43,9 +48,7 @@ def test_deprecated_str_arg():
 
 
 def test_use_external_df():
-    TESTDATA_1t48 = os.path.join(
-        os.path.dirname(__file__), "data", "1t48_995.pdb"
-    )
+    TESTDATA_1t48 = str(TEST_DATA.joinpath("1t48_995.pdb"))
 
     p1t48 = PandasPdb()
     p1t48.read_pdb(TESTDATA_1t48)
diff --git a/biopandas/pdb/tests/test_gyradius.py b/tests/pdb/test_gyradius.py
similarity index 86%
rename from biopandas/pdb/tests/test_gyradius.py
rename to tests/pdb/test_gyradius.py
index ef4f4c8..7bba7a5 100644
--- a/biopandas/pdb/tests/test_gyradius.py
+++ b/tests/pdb/test_gyradius.py
@@ -4,12 +4,22 @@
 # Project Website: http://rasbt.github.io/biopandas/
 # Code Repository: https://github.com/rasbt/biopandas
 
-import os
+
+import sys
+
+if sys.version_info >= (3, 9):
+    import importlib.resources as pkg_resources
+else:
+    import importlib_resources as pkg_resources
 
 import pytest
+
+import tests.pdb.data
 from biopandas.pdb import PandasPdb
 
-TESTDATA_1t48 = os.path.join(os.path.dirname(__file__), "data", "1t48_995.pdb")
+TEST_DATA = pkg_resources.files(tests.pdb.data)
+
+TESTDATA_1t48 = str(TEST_DATA.joinpath("1t48_995.pdb"))
 
 p1t48 = PandasPdb()
 p1t48.read_pdb(TESTDATA_1t48)
diff --git a/biopandas/pdb/tests/test_impute.py b/tests/pdb/test_impute.py
similarity index 81%
rename from biopandas/pdb/tests/test_impute.py
rename to tests/pdb/test_impute.py
index 6035450..d188ef8 100644
--- a/biopandas/pdb/tests/test_impute.py
+++ b/tests/pdb/test_impute.py
@@ -5,13 +5,20 @@
 # Code Repository: https://github.com/rasbt/biopandas
 
 
-import os
+import sys
 
+if sys.version_info >= (3, 9):
+    import importlib.resources as pkg_resources
+else:
+    import importlib_resources as pkg_resources
+
+import tests.pdb.data
 from biopandas.pdb import PandasPdb
 
-TESTDATA_FILENAME = os.path.join(
-    os.path.dirname(__file__), "data", "3eiy_stripped_no_ele.pdb"
-)
+TEST_DATA = pkg_resources.files(tests.pdb.data)
+
+
+TESTDATA_FILENAME = str(TEST_DATA.joinpath("3eiy_stripped_no_ele.pdb"))
 
 ppdb = PandasPdb()
 ppdb.read_pdb(TESTDATA_FILENAME)
diff --git a/biopandas/pdb/tests/test_multiple_models.py b/tests/pdb/test_multiple_models.py
similarity index 78%
rename from biopandas/pdb/tests/test_multiple_models.py
rename to tests/pdb/test_multiple_models.py
index 85f0126..36e2780 100644
--- a/biopandas/pdb/tests/test_multiple_models.py
+++ b/tests/pdb/test_multiple_models.py
@@ -4,11 +4,19 @@
 # License: BSD 3 clause
 # Project Website: http://rasbt.github.io/biopandas/
 # Code Repository: https://github.com/rasbt/biopandas
-import os
+import sys
 
+if sys.version_info >= (3, 9):
+    import importlib.resources as pkg_resources
+else:
+    import importlib_resources as pkg_resources
+
+import tests.pdb.data
 from biopandas.pdb import PandasPdb
 
-TESTDATA_FILENAME = os.path.join(os.path.dirname(__file__), "data", "2jyf.pdb")
+TEST_DATA = pkg_resources.files(tests.pdb.data)
+
+TESTDATA_FILENAME = str(TEST_DATA.joinpath("2jyf.pdb"))
 
 
 def test_get_index_df():
diff --git a/biopandas/pdb/tests/test_read_pdb.py b/tests/pdb/test_read_pdb.py
similarity index 92%
rename from biopandas/pdb/tests/test_read_pdb.py
rename to tests/pdb/test_read_pdb.py
index 4477830..abb5cdc 100644
--- a/biopandas/pdb/tests/test_read_pdb.py
+++ b/tests/pdb/test_read_pdb.py
@@ -5,29 +5,30 @@
 # Code Repository: https://github.com/rasbt/biopandas
 
 
-import os
+import sys
+
+if sys.version_info >= (3, 9):
+    import importlib.resources as pkg_resources
+else:
+    import importlib_resources as pkg_resources
 from urllib.error import HTTPError
 
 import numpy as np
 import pandas as pd
 import pytest
+
+import tests.pdb.data
 from biopandas.pdb import PandasPdb
-from biopandas.testutils import assert_raises
-
-TESTDATA_FILENAME = os.path.join(os.path.dirname(__file__), "data", "3eiy.pdb")
-TESTDATA_FILENAME2 = os.path.join(
-    os.path.dirname(__file__), "data", "4eiy_anisouchunk.pdb"
-)
-TESTDATA_FILENAME_GZ = os.path.join(
-    os.path.dirname(__file__), "data", "3eiy.pdb.gz"
-)
-TESTDATA_FILENAME_AF2_V4 = os.path.join(
-    os.path.dirname(__file__), "data", "AF-Q5VSL9-F1-model_v4.pdb"
-)
-
-TESTDATA_FILENAME_AF2_V3 = os.path.join(
-    os.path.dirname(__file__), "data", "AF-Q5VSL9-F1-model_v3.pdb"
-)
+from tests.testutils import assert_raises
+
+TEST_DATA = pkg_resources.files(tests.pdb.data)
+
+TESTDATA_FILENAME = str(TEST_DATA.joinpath("3eiy.pdb"))
+TESTDATA_FILENAME2 = str(TEST_DATA.joinpath("4eiy_anisouchunk.pdb"))
+TESTDATA_FILENAME_GZ = str(TEST_DATA.joinpath("3eiy.pdb.gz"))
+TESTDATA_FILENAME_AF2_V4 = str(TEST_DATA.joinpath("AF-Q5VSL9-F1-model_v4.pdb"))
+
+TESTDATA_FILENAME_AF2_V3 = str(TEST_DATA.joinpath("AF-Q5VSL9-F1-model_v3.pdb"))
 
 ATOM_DF_COLUMNS = [
     "record_name",
diff --git a/biopandas/pdb/tests/test_rmsd.py b/tests/pdb/test_rmsd.py
similarity index 77%
rename from biopandas/pdb/tests/test_rmsd.py
rename to tests/pdb/test_rmsd.py
index 88c142b..578d1b8 100644
--- a/biopandas/pdb/tests/test_rmsd.py
+++ b/tests/pdb/test_rmsd.py
@@ -4,23 +4,26 @@
 # Project Website: http://rasbt.github.io/biopandas/
 # Code Repository: https://github.com/rasbt/biopandas
 
-import os
+import sys
+
+if sys.version_info >= (3, 9):
+    import importlib.resources as pkg_resources
+else:
+    import importlib_resources as pkg_resources
 
 import pytest
+
+import tests.pdb.data
 from biopandas.pdb import PandasPdb
 
-TESTDATA_1t48 = os.path.join(os.path.dirname(__file__), "data", "1t48_995.pdb")
-TESTDATA_1t49 = os.path.join(os.path.dirname(__file__), "data", "1t49_995.pdb")
-TESTDATA_lig1 = os.path.join(
-    os.path.dirname(__file__), "data", "lig_conf_1.pdb"
-)
-TESTDATA_lig2 = os.path.join(
-    os.path.dirname(__file__), "data", "lig_conf_2.pdb"
-)
-
-TESTDATA_rna = os.path.join(
-    os.path.dirname(__file__), "data", "1ehz-rna_short.pdb"
-)
+TEST_DATA = pkg_resources.files(tests.pdb.data)
+
+TESTDATA_1t48 = str(TEST_DATA.joinpath("1t48_995.pdb"))
+TESTDATA_1t49 = str(TEST_DATA.joinpath("1t49_995.pdb"))
+TESTDATA_lig1 = str(TEST_DATA.joinpath("lig_conf_1.pdb"))
+TESTDATA_lig2 = str(TEST_DATA.joinpath("lig_conf_2.pdb"))
+
+TESTDATA_rna = str(TEST_DATA.joinpath("1ehz-rna_short.pdb"))
 
 p1t48 = PandasPdb()
 p1t48.read_pdb(TESTDATA_1t48)
diff --git a/biopandas/pdb/tests/test_write_pdb.py b/tests/pdb/test_write_pdb.py
similarity index 90%
rename from biopandas/pdb/tests/test_write_pdb.py
rename to tests/pdb/test_write_pdb.py
index 352e51b..f16e5ad 100644
--- a/biopandas/pdb/tests/test_write_pdb.py
+++ b/tests/pdb/test_write_pdb.py
@@ -4,21 +4,27 @@
 # Project Website: http://rasbt.github.io/biopandas/
 # Code Repository: https://github.com/rasbt/biopandas
 
+import sys
+
+if sys.version_info >= (3, 9):
+    import importlib.resources as pkg_resources
+else:
+    import importlib_resources as pkg_resources
 import os
 import warnings
 
 import pandas as pd
+
+import tests.pdb.data
 from biopandas.pdb import PandasPdb
 
-TESTDATA_FILENAME = os.path.join(os.path.dirname(__file__), "data", "3eiy.pdb")
-TESTDATA_FILENAME2 = os.path.join(
-    os.path.dirname(__file__), "data", "4eiy_anisouchunk.pdb"
-)
-TESTDATA_FILENAME3 = os.path.join(
-    os.path.dirname(__file__), "data", "5mtn_multichain.pdb"
-)
-OUTFILE = os.path.join(os.path.dirname(__file__), "data", "tmp.pdb")
-OUTFILE_GZ = os.path.join(os.path.dirname(__file__), "data", "tmp.pdb.gz")
+TEST_DATA = pkg_resources.files(tests.pdb.data)
+
+TESTDATA_FILENAME = str(TEST_DATA.joinpath("3eiy.pdb"))
+TESTDATA_FILENAME2 = str(TEST_DATA.joinpath("4eiy_anisouchunk.pdb"))
+TESTDATA_FILENAME3 = str(TEST_DATA.joinpath("5mtn_multichain.pdb"))
+OUTFILE = str(TEST_DATA.joinpath("tmp.pdb"))
+OUTFILE_GZ = str(TEST_DATA.joinpath("tmp.pdb.gz"))
 
 hetatm = ""
 with open(TESTDATA_FILENAME, "r") as f:
diff --git a/biopandas/testutils/__init__.py b/tests/testutils/__init__.py
similarity index 100%
rename from biopandas/testutils/__init__.py
rename to tests/testutils/__init__.py
diff --git a/biopandas/testutils/testutils.py b/tests/testutils/testutils.py
similarity index 94%
rename from biopandas/testutils/testutils.py
rename to tests/testutils/testutils.py
index 6d71643..4560679 100644
--- a/biopandas/testutils/testutils.py
+++ b/tests/testutils/testutils.py
@@ -15,7 +15,8 @@ def assertMultiLineEqual(first, second, preserve_newline=True, msg=None):
     if first != second:
         message = "".join(
             difflib.ndiff(
-                first.splitlines(preserve_newline), second.splitlines(preserve_newline)
+                first.splitlines(preserve_newline),
+                second.splitlines(preserve_newline),
             )
         )
         if msg: