diff --git a/importlib_resources/tests/data01/__init__.py b/importlib_resources/tests/data01/__init__.py
deleted file mode 100644
index e69de29b..00000000
diff --git a/importlib_resources/tests/data01/binary.file b/importlib_resources/tests/data01/binary.file
deleted file mode 100644
index eaf36c1d..00000000
Binary files a/importlib_resources/tests/data01/binary.file and /dev/null differ
diff --git a/importlib_resources/tests/data01/subdirectory/__init__.py b/importlib_resources/tests/data01/subdirectory/__init__.py
deleted file mode 100644
index e69de29b..00000000
diff --git a/importlib_resources/tests/data01/subdirectory/binary.file b/importlib_resources/tests/data01/subdirectory/binary.file
deleted file mode 100644
index 5bd8bb89..00000000
--- a/importlib_resources/tests/data01/subdirectory/binary.file
+++ /dev/null
@@ -1 +0,0 @@
-
\ No newline at end of file
diff --git a/importlib_resources/tests/data01/utf-16.file b/importlib_resources/tests/data01/utf-16.file
deleted file mode 100644
index 2cb77229..00000000
Binary files a/importlib_resources/tests/data01/utf-16.file and /dev/null differ
diff --git a/importlib_resources/tests/data01/utf-8.file b/importlib_resources/tests/data01/utf-8.file
deleted file mode 100644
index 1c0132ad..00000000
--- a/importlib_resources/tests/data01/utf-8.file
+++ /dev/null
@@ -1 +0,0 @@
-Hello, UTF-8 world!
diff --git a/importlib_resources/tests/data02/__init__.py b/importlib_resources/tests/data02/__init__.py
deleted file mode 100644
index e69de29b..00000000
diff --git a/importlib_resources/tests/data02/one/__init__.py b/importlib_resources/tests/data02/one/__init__.py
deleted file mode 100644
index e69de29b..00000000
diff --git a/importlib_resources/tests/data02/one/resource1.txt b/importlib_resources/tests/data02/one/resource1.txt
deleted file mode 100644
index 61a813e4..00000000
--- a/importlib_resources/tests/data02/one/resource1.txt
+++ /dev/null
@@ -1 +0,0 @@
-one resource
diff --git a/importlib_resources/tests/data02/subdirectory/subsubdir/resource.txt b/importlib_resources/tests/data02/subdirectory/subsubdir/resource.txt
deleted file mode 100644
index 48f587a2..00000000
--- a/importlib_resources/tests/data02/subdirectory/subsubdir/resource.txt
+++ /dev/null
@@ -1 +0,0 @@
-a resource
\ No newline at end of file
diff --git a/importlib_resources/tests/data02/two/__init__.py b/importlib_resources/tests/data02/two/__init__.py
deleted file mode 100644
index e69de29b..00000000
diff --git a/importlib_resources/tests/data02/two/resource2.txt b/importlib_resources/tests/data02/two/resource2.txt
deleted file mode 100644
index a80ce46e..00000000
--- a/importlib_resources/tests/data02/two/resource2.txt
+++ /dev/null
@@ -1 +0,0 @@
-two resource
diff --git a/importlib_resources/tests/namespacedata01/binary.file b/importlib_resources/tests/namespacedata01/binary.file
deleted file mode 100644
index eaf36c1d..00000000
Binary files a/importlib_resources/tests/namespacedata01/binary.file and /dev/null differ
diff --git a/importlib_resources/tests/namespacedata01/subdirectory/binary.file b/importlib_resources/tests/namespacedata01/subdirectory/binary.file
deleted file mode 100644
index 100f5064..00000000
--- a/importlib_resources/tests/namespacedata01/subdirectory/binary.file
+++ /dev/null
@@ -1 +0,0 @@
-

\ No newline at end of file
diff --git a/importlib_resources/tests/namespacedata01/utf-16.file b/importlib_resources/tests/namespacedata01/utf-16.file
deleted file mode 100644
index 2cb77229..00000000
Binary files a/importlib_resources/tests/namespacedata01/utf-16.file and /dev/null differ
diff --git a/importlib_resources/tests/namespacedata01/utf-8.file b/importlib_resources/tests/namespacedata01/utf-8.file
deleted file mode 100644
index 1c0132ad..00000000
--- a/importlib_resources/tests/namespacedata01/utf-8.file
+++ /dev/null
@@ -1 +0,0 @@
-Hello, UTF-8 world!
diff --git a/importlib_resources/tests/test_contents.py b/importlib_resources/tests/test_contents.py
index 7dc3b0a6..741a7407 100644
--- a/importlib_resources/tests/test_contents.py
+++ b/importlib_resources/tests/test_contents.py
@@ -1,7 +1,6 @@
 import unittest
 import importlib_resources as resources
 
-from . import data01
 from . import util
 
 
@@ -19,16 +18,17 @@ def test_contents(self):
         assert self.expected <= contents
 
 
-class ContentsDiskTests(ContentsTests, unittest.TestCase):
-    def setUp(self):
-        self.data = data01
+class ContentsDiskTests(ContentsTests, util.DiskSetup, unittest.TestCase):
+    pass
 
 
 class ContentsZipTests(ContentsTests, util.ZipSetup, unittest.TestCase):
     pass
 
 
-class ContentsNamespaceTests(ContentsTests, unittest.TestCase):
+class ContentsNamespaceTests(ContentsTests, util.DiskSetup, unittest.TestCase):
+    MODULE = 'namespacedata01'
+
     expected = {
         # no __init__ because of namespace design
         'binary.file',
@@ -36,8 +36,3 @@ class ContentsNamespaceTests(ContentsTests, unittest.TestCase):
         'utf-16.file',
         'utf-8.file',
     }
-
-    def setUp(self):
-        from . import namespacedata01
-
-        self.data = namespacedata01
diff --git a/importlib_resources/tests/test_files.py b/importlib_resources/tests/test_files.py
index 3e86ec64..ce0f74a7 100644
--- a/importlib_resources/tests/test_files.py
+++ b/importlib_resources/tests/test_files.py
@@ -6,7 +6,6 @@
 
 import importlib_resources as resources
 from ..abc import Traversable
-from . import data01
 from . import util
 from . import _path
 from .compat.py39 import os_helper
@@ -48,20 +47,16 @@ def test_old_parameter(self):
             resources.files(package=self.data)
 
 
-class OpenDiskTests(FilesTests, unittest.TestCase):
-    def setUp(self):
-        self.data = data01
+class OpenDiskTests(FilesTests, util.DiskSetup, unittest.TestCase):
+    pass
 
 
 class OpenZipTests(FilesTests, util.ZipSetup, unittest.TestCase):
     pass
 
 
-class OpenNamespaceTests(FilesTests, unittest.TestCase):
-    def setUp(self):
-        from . import namespacedata01
-
-        self.data = namespacedata01
+class OpenNamespaceTests(FilesTests, util.DiskSetup, unittest.TestCase):
+    MODULE = 'namespacedata01'
 
 
 class OpenNamespaceZipTests(FilesTests, util.ZipSetup, unittest.TestCase):
diff --git a/importlib_resources/tests/test_functional.py b/importlib_resources/tests/test_functional.py
index 69706cf7..9ec717f2 100644
--- a/importlib_resources/tests/test_functional.py
+++ b/importlib_resources/tests/test_functional.py
@@ -1,6 +1,7 @@
 import unittest
 import os
 import contextlib
+import importlib
 
 try:
     from test.support.warnings_helper import ignore_warnings, check_warnings
@@ -10,22 +11,33 @@
 
 import importlib_resources as resources
 
+from . import util
+
 # Since the functional API forwards to Traversable, we only test
 # filesystem resources here -- not zip files, namespace packages etc.
 # We do test for two kinds of Anchor, though.
 
 
 class StringAnchorMixin:
-    anchor01 = 'importlib_resources.tests.data01'
-    anchor02 = 'importlib_resources.tests.data02'
+    anchor01 = 'data01'
+    anchor02 = 'data02'
 
 
 class ModuleAnchorMixin:
-    from . import data01 as anchor01
-    from . import data02 as anchor02
+    @property
+    def anchor01(self):
+        return importlib.import_module('data01')
+
+    @property
+    def anchor02(self):
+        return importlib.import_module('data02')
+
 
+class FunctionalAPIBase(util.DiskSetup):
+    def setUp(self):
+        super().setUp()
+        self.load_fixture('data02')
 
-class FunctionalAPIBase:
     def _gen_resourcetxt_path_parts(self):
         """Yield various names of a text file in anchor02, each in a subTest"""
         for path_parts in (
@@ -227,16 +239,16 @@ def test_text_errors(self):
 
 
 class FunctionalAPITest_StringAnchor(
-    unittest.TestCase,
-    FunctionalAPIBase,
     StringAnchorMixin,
+    FunctionalAPIBase,
+    unittest.TestCase,
 ):
     pass
 
 
 class FunctionalAPITest_ModuleAnchor(
-    unittest.TestCase,
-    FunctionalAPIBase,
     ModuleAnchorMixin,
+    FunctionalAPIBase,
+    unittest.TestCase,
 ):
     pass
diff --git a/importlib_resources/tests/test_open.py b/importlib_resources/tests/test_open.py
index 44f1018a..c40bb8c6 100644
--- a/importlib_resources/tests/test_open.py
+++ b/importlib_resources/tests/test_open.py
@@ -1,7 +1,6 @@
 import unittest
 
 import importlib_resources as resources
-from . import data01
 from . import util
 
 
@@ -65,16 +64,12 @@ def test_open_text_FileNotFoundError(self):
             target.open(encoding='utf-8')
 
 
-class OpenDiskTests(OpenTests, unittest.TestCase):
-    def setUp(self):
-        self.data = data01
-
+class OpenDiskTests(OpenTests, util.DiskSetup, unittest.TestCase):
+    pass
 
-class OpenDiskNamespaceTests(OpenTests, unittest.TestCase):
-    def setUp(self):
-        from . import namespacedata01
 
-        self.data = namespacedata01
+class OpenDiskNamespaceTests(OpenTests, util.DiskSetup, unittest.TestCase):
+    MODULE = 'namespacedata01'
 
 
 class OpenZipTests(OpenTests, util.ZipSetup, unittest.TestCase):
@@ -82,7 +77,7 @@ class OpenZipTests(OpenTests, util.ZipSetup, unittest.TestCase):
 
 
 class OpenNamespaceZipTests(OpenTests, util.ZipSetup, unittest.TestCase):
-    ZIP_MODULE = 'namespacedata01'
+    MODULE = 'namespacedata01'
 
 
 if __name__ == '__main__':
diff --git a/importlib_resources/tests/test_path.py b/importlib_resources/tests/test_path.py
index c3e1cbb4..1e30f2bc 100644
--- a/importlib_resources/tests/test_path.py
+++ b/importlib_resources/tests/test_path.py
@@ -3,7 +3,6 @@
 import unittest
 
 import importlib_resources as resources
-from . import data01
 from . import util
 
 
@@ -25,9 +24,7 @@ def test_reading(self):
             self.assertEqual('Hello, UTF-8 world!\n', path.read_text(encoding='utf-8'))
 
 
-class PathDiskTests(PathTests, unittest.TestCase):
-    data = data01
-
+class PathDiskTests(PathTests, util.DiskSetup, unittest.TestCase):
     def test_natural_path(self):
         """
         Guarantee the internal implementation detail that
diff --git a/importlib_resources/tests/test_read.py b/importlib_resources/tests/test_read.py
index 97d90128..6780a2d1 100644
--- a/importlib_resources/tests/test_read.py
+++ b/importlib_resources/tests/test_read.py
@@ -1,7 +1,6 @@
 import unittest
 import importlib_resources as resources
 
-from . import data01
 from . import util
 from importlib import import_module
 
@@ -52,8 +51,8 @@ def test_read_text_with_errors(self):
         )
 
 
-class ReadDiskTests(ReadTests, unittest.TestCase):
-    data = data01
+class ReadDiskTests(ReadTests, util.DiskSetup, unittest.TestCase):
+    pass
 
 
 class ReadZipTests(ReadTests, util.ZipSetup, unittest.TestCase):
@@ -69,15 +68,12 @@ def test_read_submodule_resource_by_name(self):
         self.assertEqual(result, bytes(range(4, 8)))
 
 
-class ReadNamespaceTests(ReadTests, unittest.TestCase):
-    def setUp(self):
-        from . import namespacedata01
-
-        self.data = namespacedata01
+class ReadNamespaceTests(ReadTests, util.DiskSetup, unittest.TestCase):
+    MODULE = 'namespacedata01'
 
 
 class ReadNamespaceZipTests(ReadTests, util.ZipSetup, unittest.TestCase):
-    ZIP_MODULE = 'namespacedata01'
+    MODULE = 'namespacedata01'
 
     def test_read_submodule_resource(self):
         submodule = import_module('namespacedata01.subdirectory')
diff --git a/importlib_resources/tests/test_reader.py b/importlib_resources/tests/test_reader.py
index 95c2fc85..0a77eb40 100644
--- a/importlib_resources/tests/test_reader.py
+++ b/importlib_resources/tests/test_reader.py
@@ -1,16 +1,21 @@
 import os.path
-import sys
 import pathlib
 import unittest
 
 from importlib import import_module
 from importlib_resources.readers import MultiplexedPath, NamespaceReader
 
+from . import util
 
-class MultiplexedPathTest(unittest.TestCase):
-    @classmethod
-    def setUpClass(cls):
-        cls.folder = pathlib.Path(__file__).parent / 'namespacedata01'
+
+class MultiplexedPathTest(util.DiskSetup, unittest.TestCase):
+    MODULE = 'namespacedata01'
+
+    def setUp(self):
+        super().setUp()
+        self.folder = pathlib.Path(self.data.__path__[0])
+        self.data01 = pathlib.Path(self.load_fixture('data01').__file__).parent
+        self.data02 = pathlib.Path(self.load_fixture('data02').__file__).parent
 
     def test_init_no_paths(self):
         with self.assertRaises(FileNotFoundError):
@@ -31,9 +36,8 @@ def test_iterdir(self):
         )
 
     def test_iterdir_duplicate(self):
-        data01 = pathlib.Path(__file__).parent.joinpath('data01')
         contents = {
-            path.name for path in MultiplexedPath(self.folder, data01).iterdir()
+            path.name for path in MultiplexedPath(self.folder, self.data01).iterdir()
         }
         for remove in ('__pycache__', '__init__.pyc'):
             try:
@@ -61,9 +65,8 @@ def test_open_file(self):
             path.open()
 
     def test_join_path(self):
-        data01 = pathlib.Path(__file__).parent.joinpath('data01')
-        prefix = str(data01.parent)
-        path = MultiplexedPath(self.folder, data01)
+        prefix = str(self.folder.parent)
+        path = MultiplexedPath(self.folder, self.data01)
         self.assertEqual(
             str(path.joinpath('binary.file'))[len(prefix) + 1 :],
             os.path.join('namespacedata01', 'binary.file'),
@@ -83,10 +86,8 @@ def test_join_path_compound(self):
         assert not path.joinpath('imaginary/foo.py').exists()
 
     def test_join_path_common_subdir(self):
-        data01 = pathlib.Path(__file__).parent.joinpath('data01')
-        data02 = pathlib.Path(__file__).parent.joinpath('data02')
-        prefix = str(data01.parent)
-        path = MultiplexedPath(data01, data02)
+        prefix = str(self.data02.parent)
+        path = MultiplexedPath(self.data01, self.data02)
         self.assertIsInstance(path.joinpath('subdirectory'), MultiplexedPath)
         self.assertEqual(
             str(path.joinpath('subdirectory', 'subsubdir'))[len(prefix) + 1 :],
@@ -106,16 +107,8 @@ def test_name(self):
         )
 
 
-class NamespaceReaderTest(unittest.TestCase):
-    site_dir = str(pathlib.Path(__file__).parent)
-
-    @classmethod
-    def setUpClass(cls):
-        sys.path.append(cls.site_dir)
-
-    @classmethod
-    def tearDownClass(cls):
-        sys.path.remove(cls.site_dir)
+class NamespaceReaderTest(util.DiskSetup, unittest.TestCase):
+    MODULE = 'namespacedata01'
 
     def test_init_error(self):
         with self.assertRaises(ValueError):
@@ -125,7 +118,7 @@ def test_resource_path(self):
         namespacedata01 = import_module('namespacedata01')
         reader = NamespaceReader(namespacedata01.__spec__.submodule_search_locations)
 
-        root = os.path.abspath(os.path.join(__file__, '..', 'namespacedata01'))
+        root = self.data.__path__[0]
         self.assertEqual(
             reader.resource_path('binary.file'), os.path.join(root, 'binary.file')
         )
@@ -134,9 +127,8 @@ def test_resource_path(self):
         )
 
     def test_files(self):
-        namespacedata01 = import_module('namespacedata01')
-        reader = NamespaceReader(namespacedata01.__spec__.submodule_search_locations)
-        root = os.path.abspath(os.path.join(__file__, '..', 'namespacedata01'))
+        reader = NamespaceReader(self.data.__spec__.submodule_search_locations)
+        root = self.data.__path__[0]
         self.assertIsInstance(reader.files(), MultiplexedPath)
         self.assertEqual(repr(reader.files()), f"MultiplexedPath('{root}')")
 
diff --git a/importlib_resources/tests/test_resource.py b/importlib_resources/tests/test_resource.py
index 32aa909a..a0da6a35 100644
--- a/importlib_resources/tests/test_resource.py
+++ b/importlib_resources/tests/test_resource.py
@@ -1,9 +1,6 @@
-import sys
 import unittest
 import importlib_resources as resources
-import pathlib
 
-from . import data01
 from . import util
 from importlib import import_module
 
@@ -25,9 +22,8 @@ def test_is_dir(self):
         self.assertTrue(target.is_dir())
 
 
-class ResourceDiskTests(ResourceTests, unittest.TestCase):
-    def setUp(self):
-        self.data = data01
+class ResourceDiskTests(ResourceTests, util.DiskSetup, unittest.TestCase):
+    pass
 
 
 class ResourceZipTests(ResourceTests, util.ZipSetup, unittest.TestCase):
@@ -38,33 +34,39 @@ def names(traversable):
     return {item.name for item in traversable.iterdir()}
 
 
-class ResourceLoaderTests(unittest.TestCase):
+class ResourceLoaderTests(util.DiskSetup, unittest.TestCase):
     def test_resource_contents(self):
         package = util.create_package(
-            file=data01, path=data01.__file__, contents=['A', 'B', 'C']
+            file=self.data, path=self.data.__file__, contents=['A', 'B', 'C']
         )
         self.assertEqual(names(resources.files(package)), {'A', 'B', 'C'})
 
     def test_is_file(self):
         package = util.create_package(
-            file=data01, path=data01.__file__, contents=['A', 'B', 'C', 'D/E', 'D/F']
+            file=self.data,
+            path=self.data.__file__,
+            contents=['A', 'B', 'C', 'D/E', 'D/F'],
         )
         self.assertTrue(resources.files(package).joinpath('B').is_file())
 
     def test_is_dir(self):
         package = util.create_package(
-            file=data01, path=data01.__file__, contents=['A', 'B', 'C', 'D/E', 'D/F']
+            file=self.data,
+            path=self.data.__file__,
+            contents=['A', 'B', 'C', 'D/E', 'D/F'],
         )
         self.assertTrue(resources.files(package).joinpath('D').is_dir())
 
     def test_resource_missing(self):
         package = util.create_package(
-            file=data01, path=data01.__file__, contents=['A', 'B', 'C', 'D/E', 'D/F']
+            file=self.data,
+            path=self.data.__file__,
+            contents=['A', 'B', 'C', 'D/E', 'D/F'],
         )
         self.assertFalse(resources.files(package).joinpath('Z').is_file())
 
 
-class ResourceCornerCaseTests(unittest.TestCase):
+class ResourceCornerCaseTests(util.DiskSetup, unittest.TestCase):
     def test_package_has_no_reader_fallback(self):
         """
         Test odd ball packages which:
@@ -73,7 +75,7 @@ def test_package_has_no_reader_fallback(self):
         # 3. Are not in a zip file
         """
         module = util.create_package(
-            file=data01, path=data01.__file__, contents=['A', 'B', 'C']
+            file=self.data, path=self.data.__file__, contents=['A', 'B', 'C']
         )
         # Give the module a dummy loader.
         module.__loader__ = object()
@@ -85,8 +87,6 @@ def test_package_has_no_reader_fallback(self):
 
 
 class ResourceFromZipsTest01(util.ZipSetup, unittest.TestCase):
-    ZIP_MODULE = 'data01'
-
     def test_is_submodule_resource(self):
         submodule = import_module('data01.subdirectory')
         self.assertTrue(resources.files(submodule).joinpath('binary.file').is_file())
@@ -118,7 +118,7 @@ def test_as_file_directory(self):
 
 
 class ResourceFromZipsTest02(util.ZipSetup, unittest.TestCase):
-    ZIP_MODULE = 'data02'
+    MODULE = 'data02'
 
     def test_unrelated_contents(self):
         """
@@ -217,16 +217,12 @@ def test_submodule_sub_contents_by_name(self):
         self.assertEqual(contents, {'binary.file'})
 
 
-class ResourceFromNamespaceDiskTests(ResourceFromNamespaceTests, unittest.TestCase):
-    site_dir = str(pathlib.Path(__file__).parent)
-
-    @classmethod
-    def setUpClass(cls):
-        sys.path.append(cls.site_dir)
-
-    @classmethod
-    def tearDownClass(cls):
-        sys.path.remove(cls.site_dir)
+class ResourceFromNamespaceDiskTests(
+    util.DiskSetup,
+    ResourceFromNamespaceTests,
+    unittest.TestCase,
+):
+    MODULE = 'namespacedata01'
 
 
 class ResourceFromNamespaceZipTests(
@@ -234,7 +230,7 @@ class ResourceFromNamespaceZipTests(
     ResourceFromNamespaceTests,
     unittest.TestCase,
 ):
-    ZIP_MODULE = 'namespacedata01'
+    MODULE = 'namespacedata01'
 
 
 if __name__ == '__main__':
diff --git a/importlib_resources/tests/util.py b/importlib_resources/tests/util.py
index b258aec0..6b901f67 100644
--- a/importlib_resources/tests/util.py
+++ b/importlib_resources/tests/util.py
@@ -6,10 +6,10 @@
 import pathlib
 import contextlib
 
-from . import data01
 from ..abc import ResourceReader
 from .compat.py39 import import_helper, os_helper
 from . import zip as zip_
+from . import _path
 
 
 from importlib.machinery import ModuleSpec
@@ -68,7 +68,7 @@ def create_package(file=None, path=None, is_package=True, contents=()):
     )
 
 
-class CommonTests(metaclass=abc.ABCMeta):
+class CommonTestsBase(metaclass=abc.ABCMeta):
     """
     Tests shared by test_open, test_path, and test_read.
     """
@@ -84,34 +84,34 @@ def test_package_name(self):
         """
         Passing in the package name should succeed.
         """
-        self.execute(data01.__name__, 'utf-8.file')
+        self.execute(self.data.__name__, 'utf-8.file')
 
     def test_package_object(self):
         """
         Passing in the package itself should succeed.
         """
-        self.execute(data01, 'utf-8.file')
+        self.execute(self.data, 'utf-8.file')
 
     def test_string_path(self):
         """
         Passing in a string for the path should succeed.
         """
         path = 'utf-8.file'
-        self.execute(data01, path)
+        self.execute(self.data, path)
 
     def test_pathlib_path(self):
         """
         Passing in a pathlib.PurePath object for the path should succeed.
         """
         path = pathlib.PurePath('utf-8.file')
-        self.execute(data01, path)
+        self.execute(self.data, path)
 
     def test_importing_module_as_side_effect(self):
         """
         The anchor package can already be imported.
         """
-        del sys.modules[data01.__name__]
-        self.execute(data01.__name__, 'utf-8.file')
+        del sys.modules[self.data.__name__]
+        self.execute(self.data.__name__, 'utf-8.file')
 
     def test_missing_path(self):
         """
@@ -141,20 +141,68 @@ def test_useless_loader(self):
             self.execute(package, 'utf-8.file')
 
 
-class ZipSetup:
-    ZIP_MODULE = 'data01'
-
+fixtures = dict(
+    data01={
+        '__init__.py': '',
+        'binary.file': bytes(range(4)),
+        'utf-16.file': 'Hello, UTF-16 world!\n'.encode('utf-16'),
+        'utf-8.file': 'Hello, UTF-8 world!\n'.encode('utf-8'),
+        'subdirectory': {
+            '__init__.py': '',
+            'binary.file': bytes(range(4, 8)),
+        },
+    },
+    data02={
+        '__init__.py': '',
+        'one': {'__init__.py': '', 'resource1.txt': 'one resource'},
+        'two': {'__init__.py': '', 'resource2.txt': 'two resource'},
+        'subdirectory': {'subsubdir': {'resource.txt': 'a resource'}},
+    },
+    namespacedata01={
+        'binary.file': bytes(range(4)),
+        'utf-16.file': 'Hello, UTF-16 world!\n'.encode('utf-16'),
+        'utf-8.file': 'Hello, UTF-8 world!\n'.encode('utf-8'),
+        'subdirectory': {
+            'binary.file': bytes(range(12, 16)),
+        },
+    },
+)
+
+
+class ModuleSetup:
     def setUp(self):
         self.fixtures = contextlib.ExitStack()
         self.addCleanup(self.fixtures.close)
 
         self.fixtures.enter_context(import_helper.isolated_modules())
+        self.data = self.load_fixture(self.MODULE)
+
+
+class ZipSetup(ModuleSetup):
+    MODULE = 'data01'
 
+    def load_fixture(self, module):
         temp_dir = self.fixtures.enter_context(os_helper.temp_dir())
         modules = pathlib.Path(temp_dir) / 'zipped modules.zip'
-        src_path = pathlib.Path(__file__).parent.joinpath(self.ZIP_MODULE)
         self.fixtures.enter_context(
-            import_helper.DirsOnSysPath(str(zip_.make_zip_file(src_path, modules)))
+            import_helper.DirsOnSysPath(
+                str(zip_.make_zip_file({module: fixtures[module]}, modules))
+            )
         )
 
-        self.data = importlib.import_module(self.ZIP_MODULE)
+        return importlib.import_module(module)
+
+
+class DiskSetup(ModuleSetup):
+    MODULE = 'data01'
+
+    def load_fixture(self, module):
+        temp_dir = self.fixtures.enter_context(os_helper.temp_dir())
+        _path.build({module: fixtures[module]}, pathlib.Path(temp_dir))
+        self.fixtures.enter_context(import_helper.DirsOnSysPath(temp_dir))
+
+        return importlib.import_module(module)
+
+
+class CommonTests(DiskSetup, CommonTestsBase):
+    pass
diff --git a/importlib_resources/tests/zip.py b/importlib_resources/tests/zip.py
index 962195a9..51ee5648 100755
--- a/importlib_resources/tests/zip.py
+++ b/importlib_resources/tests/zip.py
@@ -2,31 +2,25 @@
 Generate zip test data files.
 """
 
-import contextlib
-import os
-import pathlib
 import zipfile
 
 import zipp
 
 
-def make_zip_file(src, dst):
+def make_zip_file(tree, dst):
     """
-    Zip the files in src into a new zipfile at dst.
+    Zip the files in tree into a new zipfile at dst.
     """
     with zipfile.ZipFile(dst, 'w') as zf:
-        for src_path, rel in walk(src):
-            dst_name = src.name / pathlib.PurePosixPath(rel.as_posix())
-            zf.write(src_path, dst_name)
+        for name, contents in walk(tree):
+            zf.writestr(name, contents)
         zipp.CompleteDirs.inject(zf)
     return dst
 
 
-def walk(datapath):
-    for dirpath, dirnames, filenames in os.walk(datapath):
-        with contextlib.suppress(ValueError):
-            dirnames.remove('__pycache__')
-        for filename in filenames:
-            res = pathlib.Path(dirpath) / filename
-            rel = res.relative_to(datapath)
-            yield res, rel
+def walk(tree, prefix=''):
+    for name, contents in tree.items():
+        if isinstance(contents, dict):
+            yield from walk(contents, prefix=f'{prefix}{name}/')
+        else:
+            yield f'{prefix}{name}', contents