pythonGH-113528: Split up pathlib tests for invalid basenames.

Split test cases for invalid names into dedicated test methods. This will
make it easier to refactor tests for invalid name handling in ABCs later.

No change of coverage, just a change of test suite organisation.

Author: barneygale

Lib/test/test_pathlib/test_pathlib_abc.py

@@ -212,10 +212,13 @@ def test_eq_common(self):
         self.assertNotEqual(P(), {})
         self.assertNotEqual(P(), int)
 
-    def test_match_common(self):
+    def test_match_empty(self):
         P = self.cls
         self.assertRaises(ValueError, P('a').match, '')
         self.assertRaises(ValueError, P('a').match, '.')
+
+    def test_match_common(self):
+        P = self.cls
         # Simple relative pattern.
         self.assertTrue(P('b.py').match('b.py'))
         self.assertTrue(P('a/b.py').match('b.py'))
@@ -395,14 +398,17 @@ def test_anchor_common(self):
         self.assertEqual(P('/').anchor, sep)
         self.assertEqual(P('/a/b').anchor, sep)
 
-    def test_name_common(self):
+    def test_name_empty(self):
         P = self.cls
         self.assertEqual(P('').name, '')
         self.assertEqual(P('.').name, '')
+        self.assertEqual(P('/a/b/.').name, 'b')
+
+    def test_name_common(self):
+        P = self.cls
         self.assertEqual(P('/').name, '')
         self.assertEqual(P('a/b').name, 'b')
         self.assertEqual(P('/a/b').name, 'b')
-        self.assertEqual(P('/a/b/.').name, 'b')
         self.assertEqual(P('a/b.py').name, 'b.py')
         self.assertEqual(P('/a/b.py').name, 'b.py')
 
@@ -445,10 +451,13 @@ def test_suffixes_common(self):
         self.assertEqual(P('a/Some name. Ending with a dot.').suffixes, [])
         self.assertEqual(P('/a/Some name. Ending with a dot.').suffixes, [])
 
-    def test_stem_common(self):
+    def test_stem_empty(self):
         P = self.cls
         self.assertEqual(P('').stem, '')
         self.assertEqual(P('.').stem, '')
+
+    def test_stem_common(self):
+        P = self.cls
         self.assertEqual(P('..').stem, '..')
         self.assertEqual(P('/').stem, '')
         self.assertEqual(P('a/b').stem, 'b')
@@ -467,11 +476,17 @@ def test_with_name_common(self):
         self.assertEqual(P('/a/b.py').with_name('d.xml'), P('/a/d.xml'))
         self.assertEqual(P('a/Dot ending.').with_name('d.xml'), P('a/d.xml'))
         self.assertEqual(P('/a/Dot ending.').with_name('d.xml'), P('/a/d.xml'))
+
+    def test_with_name_empty(self):
+        P = self.cls
         self.assertRaises(ValueError, P('').with_name, 'd.xml')
         self.assertRaises(ValueError, P('.').with_name, 'd.xml')
         self.assertRaises(ValueError, P('/').with_name, 'd.xml')
         self.assertRaises(ValueError, P('a/b').with_name, '')
         self.assertRaises(ValueError, P('a/b').with_name, '.')
+
+    def test_with_name_seps(self):
+        P = self.cls
         self.assertRaises(ValueError, P('a/b').with_name, '/c')
         self.assertRaises(ValueError, P('a/b').with_name, 'c/')
         self.assertRaises(ValueError, P('a/b').with_name, 'c/d')
@@ -485,11 +500,17 @@ def test_with_stem_common(self):
         self.assertEqual(P('/a/b.tar.gz').with_stem('d'), P('/a/d.gz'))
         self.assertEqual(P('a/Dot ending.').with_stem('d'), P('a/d'))
         self.assertEqual(P('/a/Dot ending.').with_stem('d'), P('/a/d'))
+
+    def test_with_stem_empty(self):
+        P = self.cls
         self.assertRaises(ValueError, P('').with_stem, 'd')
         self.assertRaises(ValueError, P('.').with_stem, 'd')
         self.assertRaises(ValueError, P('/').with_stem, 'd')
         self.assertRaises(ValueError, P('a/b').with_stem, '')
         self.assertRaises(ValueError, P('a/b').with_stem, '.')
+
+    def test_with_stem_seps(self):
+        P = self.cls
         self.assertRaises(ValueError, P('a/b').with_stem, '/c')
         self.assertRaises(ValueError, P('a/b').with_stem, 'c/')
         self.assertRaises(ValueError, P('a/b').with_stem, 'c/d')
@@ -503,10 +524,16 @@ def test_with_suffix_common(self):
         # Stripping suffix.
         self.assertEqual(P('a/b.py').with_suffix(''), P('a/b'))
         self.assertEqual(P('/a/b').with_suffix(''), P('/a/b'))
+
+    def test_with_suffix_empty(self):
+        P = self.cls
         # Path doesn't have a "filename" component.
         self.assertRaises(ValueError, P('').with_suffix, '.gz')
         self.assertRaises(ValueError, P('.').with_suffix, '.gz')
         self.assertRaises(ValueError, P('/').with_suffix, '.gz')
+
+    def test_with_suffix_seps(self):
+        P = self.cls
         # Invalid suffix.
         self.assertRaises(ValueError, P('a/b').with_suffix, 'gz')
         self.assertRaises(ValueError, P('a/b').with_suffix, '/')