[Apache v2] Implement delete_child() (#7521)

* Implement delete_child

* Fix linter

certbot-apache/certbot_apache/augeasparser.py

@@ -300,9 +300,18 @@ class AugeasBlockNode(AugeasDirectiveNode):
 
         return nodes
 
-    def delete_child(self, child):  # pragma: no cover
-        """Deletes a ParserNode from the sequence of children"""
-        pass
+    def delete_child(self, child):
+        """
+        Deletes a ParserNode from the sequence of children, and raises an
+        exception if it's unable to do so.
+        :param AugeasParserNode: child: A node to delete.
+        """
+        if not self.parser.aug.remove(child.metadata["augeaspath"]):
+
+            raise errors.PluginError(
+                ("Could not delete child node, the Augeas path: {} doesn't " +
+                 "seem to exist.").format(child.metadata["augeaspath"])
+            )
 
     def unsaved_files(self):
         """Returns a list of unsaved filepaths"""

certbot-apache/certbot_apache/tests/augeasnode_test.py

@@ -144,6 +144,24 @@ class AugeasParserNodeTest(util.ApacheTest):  # pylint: disable=too-many-public-
                 found = True
         self.assertTrue(found)
 
+    def test_delete_child(self):
+        listens = self.config.parser_root.find_directives("Listen")
+        self.assertEqual(len(listens), 1)
+        self.config.parser_root.primary.delete_child(listens[0])
+
+        listens = self.config.parser_root.find_directives("Listen")
+        self.assertEqual(len(listens), 0)
+
+    def test_delete_child_not_found(self):
+        listen = self.config.parser_root.find_directives("Listen")[0]
+        listen.primary.metadata["augeaspath"] = "/files/something/nonexistent"
+
+        self.assertRaises(
+            errors.PluginError,
+            self.config.parser_root.delete_child,
+            listen
+        )
+
     def test_add_child_block(self):
         nb = self.config.parser_root.primary.add_child_block(
             "NewBlock",