GH-73991: pathlib ABC tests: add `DummyPath.unlink()` and `rmdir()` (#120715)

In preparation for the addition of `PathBase.rmtree()`, implement
`DummyPath.unlink()` and `rmdir()`, and move corresponding tests into
`test_pathlib_abc` so they're run against `DummyPath`.

Lib/test/test_pathlib/test_pathlib.py

@@ -764,25 +764,6 @@ class PathTest(test_pathlib_abc.DummyPathTest, PurePathTest):
         self.assertEqual(expected_gid, gid_2)
         self.assertEqual(expected_name, link.group(follow_symlinks=False))
 
-    def test_unlink(self):
-        p = self.cls(self.base) / 'fileA'
-        p.unlink()
-        self.assertFileNotFound(p.stat)
-        self.assertFileNotFound(p.unlink)
-
-    def test_unlink_missing_ok(self):
-        p = self.cls(self.base) / 'fileAAA'
-        self.assertFileNotFound(p.unlink)
-        p.unlink(missing_ok=True)
-
-    def test_rmdir(self):
-        p = self.cls(self.base) / 'dirA'
-        for q in p.iterdir():
-            q.unlink()
-        p.rmdir()
-        self.assertFileNotFound(p.stat)
-        self.assertFileNotFound(p.unlink)
-
     @os_helper.skip_unless_hardlink
     def test_hardlink_to(self):
         P = self.cls(self.base)

Lib/test/test_pathlib/test_pathlib_abc.py

@@ -1496,7 +1496,7 @@ class DummyPath(PathBase):
         if path in self._files:
             raise NotADirectoryError(errno.ENOTDIR, "Not a directory", path)
         elif path in self._directories:
-            return (self / name for name in self._directories[path])
+            return iter([self / name for name in self._directories[path]])
         else:
             raise FileNotFoundError(errno.ENOENT, "File not found", path)
 
@@ -1517,6 +1517,37 @@ class DummyPath(PathBase):
             self.parent.mkdir(parents=True, exist_ok=True)
             self.mkdir(mode, parents=False, exist_ok=exist_ok)
 
+    def unlink(self, missing_ok=False):
+        path_obj = self.parent.resolve(strict=True) / self.name
+        path = str(path_obj)
+        name = path_obj.name
+        parent = str(path_obj.parent)
+        if path in self._directories:
+            raise IsADirectoryError(errno.EISDIR, "Is a directory", path)
+        elif path in self._files:
+            self._directories[parent].remove(name)
+            del self._files[path]
+        elif path in self._symlinks:
+            self._directories[parent].remove(name)
+            del self._symlinks[path]
+        elif not missing_ok:
+            raise FileNotFoundError(errno.ENOENT, "File not found", path)
+
+    def rmdir(self):
+        path_obj = self.parent.resolve(strict=True) / self.name
+        path = str(path_obj)
+        if path in self._files or path in self._symlinks:
+            raise NotADirectoryError(errno.ENOTDIR, "Not a directory", path)
+        elif path not in self._directories:
+            raise FileNotFoundError(errno.ENOENT, "File not found", path)
+        elif self._directories[path]:
+            raise OSError(errno.ENOTEMPTY, "Directory not empty", path)
+        else:
+            name = path_obj.name
+            parent = str(path_obj.parent)
+            self._directories[parent].remove(name)
+            del self._directories[path]
+
 
 class DummyPathTest(DummyPurePathTest):
     """Tests for PathBase methods that use stat(), open() and iterdir()."""
@@ -2400,6 +2431,25 @@ class DummyPathTest(DummyPurePathTest):
     def test_complex_symlinks_relative_dot_dot(self):
         self._check_complex_symlinks(self.parser.join('dirA', '..'))
 
+    def test_unlink(self):
+        p = self.cls(self.base) / 'fileA'
+        p.unlink()
+        self.assertFileNotFound(p.stat)
+        self.assertFileNotFound(p.unlink)
+
+    def test_unlink_missing_ok(self):
+        p = self.cls(self.base) / 'fileAAA'
+        self.assertFileNotFound(p.unlink)
+        p.unlink(missing_ok=True)
+
+    def test_rmdir(self):
+        p = self.cls(self.base) / 'dirA'
+        for q in p.iterdir():
+            q.unlink()
+        p.rmdir()
+        self.assertFileNotFound(p.stat)
+        self.assertFileNotFound(p.unlink)
+
     def setUpWalk(self):
         # Build:
         #     TESTFN/