[3.12] gh-108303: Create Lib/test/test_dataclasses/ directory (GH-108978) (#109674)

* gh-108303: Create Lib/test/test_dataclasses/ directory (GH-108978)

Move test_dataclasses.py and its "dataclass_*.py" modules into the
new Lib/test/test_dataclasses/ subdirectory.
(cherry picked from commit 14d6e197cc)

Co-authored-by: Victor Stinner <vstinner@python.org>

* Fix Lint job: update Lib/test/.ruff.toml

---------

Co-authored-by: Victor Stinner <vstinner@python.org>

Lib/test/.ruff.toml

@@ -22,7 +22,7 @@ extend-exclude = [
     "test_capi/test_unicode.py",
     "test_ctypes/test_arrays.py",
     "test_ctypes/test_functions.py",
-    "test_dataclasses.py",
+    "test_dataclasses/__init__.py",
     "test_descr.py",
     "test_enum.py",
     "test_functools.py",

Lib/test/test_dataclasses/__init__.py

@@ -3684,10 +3684,10 @@ class TestStringAnnotations(unittest.TestCase):
                 self.assertEqual(C(10).x, 10)
 
     def test_classvar_module_level_import(self):
-        from test import dataclass_module_1
-        from test import dataclass_module_1_str
-        from test import dataclass_module_2
-        from test import dataclass_module_2_str
+        from test.test_dataclasses import dataclass_module_1
+        from test.test_dataclasses import dataclass_module_1_str
+        from test.test_dataclasses import dataclass_module_2
+        from test.test_dataclasses import dataclass_module_2_str
 
         for m in (dataclass_module_1, dataclass_module_1_str,
                   dataclass_module_2, dataclass_module_2_str,
@@ -3725,7 +3725,7 @@ class TestStringAnnotations(unittest.TestCase):
                     self.assertNotIn('not_iv4', c.__dict__)
 
     def test_text_annotations(self):
-        from test import dataclass_textanno
+        from test.test_dataclasses import dataclass_textanno
 
         self.assertEqual(
             get_type_hints(dataclass_textanno.Bar),

Makefile.pre.in

@@ -2134,6 +2134,7 @@ TESTSUBDIRS=	idlelib/idle_test \
 		test/test_capi \
 		test/test_cppext \
 		test/test_ctypes \
+		test/test_dataclasses \
 		test/test_email \
 		test/test_email/data \
 		test/test_import \