From 6de60977acd7e82ea204a04756addaef1de13c2d Mon Sep 17 00:00:00 2001
From: Amy <leiamy12@gmail.com>
Date: Mon, 15 Jun 2020 13:39:33 -0400
Subject: remove sandbox._MagicFormatMapping

add test for escape formatter
---
 src/jinja2/sandbox.py  | 32 --------------------------------
 tests/test_security.py |  7 +++++++
 2 files changed, 7 insertions(+), 32 deletions(-)

diff --git a/src/jinja2/sandbox.py b/src/jinja2/sandbox.py
index deecf61c..5c6d0946 100644
--- a/src/jinja2/sandbox.py
+++ b/src/jinja2/sandbox.py
@@ -75,37 +75,6 @@ _mutable_spec = (
 )
 
 
-class _MagicFormatMapping(abc.Mapping):
-    """This class implements a dummy wrapper to fix a bug in the Python
-    standard library for string formatting.
-
-    See https://bugs.python.org/issue13598 for information about why
-    this is necessary.
-    """
-
-    def __init__(self, args, kwargs):
-        self._args = args
-        self._kwargs = kwargs
-        self._last_index = 0
-
-    def __getitem__(self, key):
-        if key == "":
-            idx = self._last_index
-            self._last_index += 1
-            try:
-                return self._args[idx]
-            except LookupError:
-                pass
-            key = str(idx)
-        return self._kwargs[key]
-
-    def __iter__(self):
-        return iter(self._kwargs)
-
-    def __len__(self):
-        return len(self._kwargs)
-
-
 def inspect_format_method(callable):
     if not isinstance(
         callable, (types.MethodType, types.BuiltinMethodType)
@@ -395,7 +364,6 @@ class SandboxedEnvironment(Environment):
             kwargs = args[0]
             args = None
 
-        kwargs = _MagicFormatMapping(args, kwargs)
         rv = formatter.vformat(s, args, kwargs)
         return type(s)(rv)
 
diff --git a/tests/test_security.py b/tests/test_security.py
index 44ac47ab..1b64cd37 100644
--- a/tests/test_security.py
+++ b/tests/test_security.py
@@ -146,6 +146,13 @@ class TestStringFormat:
         t = env.from_string('{{ ("a{0.foo}b{1}"|safe).format({"foo": 42}, "<foo>") }}')
         assert t.render() == "a42b&lt;foo&gt;"
 
+    def test_empty_braces_format(self):
+        env = SandboxedEnvironment()
+        t1 = env.from_string('{{ ("a{}b{}").format("foo", "42")}}')
+        t2 = env.from_string('{{ ("a{}b{}"|safe).format(42, "<foo>") }}')
+        assert t1.render() == "afoob42"
+        assert t2.render() == "a42b&lt;foo&gt;"
+
 
 class TestStringFormatMap:
     def test_basic_format_safety(self):
-- 
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