fix(path): handle bytes/memoryview keys in stringify_element (#472)

[Mukller]

Problem

Fixes #472.

DeepDiff raises TypeError when comparing dicts that contain bytes keys:

from deepdiff import DeepDiff
DeepDiff({b'foo': 1}, {b'foobar': 1})
# TypeError: a bytes-like object is required, not 'str'

Root Cause

stringify_element() in deepdiff/path.py uses "'" in param to detect single quotes before choosing a quoting style. For bytes (and memoryview) objects the in operator requires a bytes needle; passing a str raises TypeError.

The crash path:

→ _diff_dict detects key change
→ _report_result → _skip_this → level.path()
→ DictRelationship.get_param_repr()
  bytes ∈ deepdiff.helper.strings → stringify_element(b'foo', quote_str="'{}'")
  → "'" in b'foo'   # TypeError

Fix

 def stringify_element(param, quote_str=None):
+    if isinstance(param, (bytes, memoryview)):
+        return repr(param)
     has_quote = "'" in param
     has_double_quote = '"' in param

repr(b'foo') → "b'foo'" is a valid Python expression that:

• does not require any additional quoting (the b'' notation is already correct)
• round-trips back to the original bytes via literal_eval
• produces the expected path root[b'foo'] when wrapped by param_repr_format

Verification

from deepdiff import DeepDiff

# Reproducer from issue — no longer crashes:
result = DeepDiff({b'foo': 1}, {b'foobar': 1})
print(result)
# {'dictionary_item_added': {"root[b'foobar']": 1},
#  'dictionary_item_removed': {"root[b'foo']": 1}}

# Existing string-key behaviour unchanged:
result2 = DeepDiff({'foo': 1}, {'bar': 1})
print(result2)
# {'dictionary_item_added': {"root['bar']": 1},
#  'dictionary_item_removed': {"root['foo']": 1}}

[Mukller]

Code Review

Bug Path

DeepDiff({b'foo': 1}, {b'foobar': 1})
  _diff_dict
    → _report_result (item added/removed)
      → _skip_this → level.path()
        → DictRelationship.get_param_repr()
          → stringify_element(b'foo', quote_str="'{}'")
              bytes ∈ helper.strings  → enters function
              "'" in b'foo'  → TypeError  ✗

Root Cause Detail

In Python, "'" in some_bytes requires the left operand to be bytes too, not str. The function was written for str params but helper.strings = (str, bytes, memoryview) causes bytes callers to reach the same code path.

Fix Correctness

For bytes / memoryview, repr() gives the canonical Python expression that is already round-trippable:

repr(b'foo')        # "b'foo'"
repr(b"it's")      # "b\"it's\""  (repr auto-chooses safe quote style)
repr(memoryview(b'x'))  # "<memory at …>"  (not parseable, but avoids crash)

Input	Before	After
b'foo'	TypeError ✗	"b'foo'" → path root[b'foo'] ✓
b"it's"	TypeError ✗	'b"it\'s"' → path root[b"it's"] ✓
'foo'	"'foo'" ✓	unchanged ✓
"it's"	'"it\'s"' ✓	unchanged ✓

Scope

Two lines inserted at the top of stringify_element. No existing string-handling logic is touched; all string-key paths are unchanged.