diff --git a/src/diffpy/pdfgui/tests/__init__.py b/src/diffpy/pdfgui/tests/__init__.py
@@ -78,28 +78,4 @@ def test():
     return result
 
 
-def testdeps():
-    """Execute all unit tests for diffpy.pdfgui and its dependencies.
-
-    Returns
-    -------
-    result : `unittest.TestResult`
-    """
-    from importlib import import_module
-
-    modulenames = """
-        diffpy.pdfgui.tests
-        diffpy.structure.tests
-        diffpy.pdffit2.tests
-        diffpy.utils.tests
-    """.split()
-    suite = unittest.TestSuite()
-    for mname in modulenames:
-        mod = import_module(mname)
-        suite.addTests(mod.testsuite())
-    runner = unittest.TextTestRunner()
-    result = runner.run(suite)
-    return result
-
-
 # End of file
diff --git a/src/diffpy/pdfgui/tests/conftest.py b/src/diffpy/pdfgui/tests/conftest.py
@@ -1,14 +1,9 @@
 import json
-import subprocess
 from pathlib import Path
 
 import pytest
 
 
-def pytest_collection_modifyitems(session, config, items):
-    subprocess.run(["python", "-m", "diffpy.pdfgui.tests.rundeps"], check=True)
-
-
 @pytest.fixture
 def user_filesystem(tmp_path):
     base_dir = Path(tmp_path)

diff --git a/src/diffpy/pdfgui/tests/rundeps.py b/src/diffpy/pdfgui/tests/rundeps.py