[4.6] Fix warnings with attrs 19.2 and fix object assertions (#… (#5944)

[4.6] Fix warnings with attrs 19.2 and fix object assertions (#5902)

src/_pytest/assertion/util.py

@@ -12,6 +12,7 @@ import _pytest._code
 from ..compat import Sequence
 from _pytest import outcomes
 from _pytest._io.saferepr import saferepr
+from _pytest.compat import ATTRS_EQ_FIELD
 
 # The _reprcompare attribute on the util module is used by the new assertion
 # interpretation code and assertion rewriter to detect this plugin was
@@ -374,7 +375,9 @@ def _compare_eq_cls(left, right, verbose, type_fns):
         fields_to_check = [field for field, info in all_fields.items() if info.compare]
     elif isattrs(left):
         all_fields = left.__attrs_attrs__
-        fields_to_check = [field.name for field in all_fields if field.cmp]
+        fields_to_check = [
+            field.name for field in all_fields if getattr(field, ATTRS_EQ_FIELD)
+        ]
 
     same = []
     diff = []

src/_pytest/compat.py

@@ -13,6 +13,7 @@ import re
 import sys
 from contextlib import contextmanager
 
+import attr
 import py
 import six
 from six import text_type
@@ -406,8 +407,8 @@ def _setup_collect_fakemodule():
 
     pytest.collect = ModuleType("pytest.collect")
     pytest.collect.__all__ = []  # used for setns
-    for attr in COLLECT_FAKEMODULE_ATTRIBUTES:
-        setattr(pytest.collect, attr, getattr(pytest, attr))
+    for attribute in COLLECT_FAKEMODULE_ATTRIBUTES:
+        setattr(pytest.collect, attribute, getattr(pytest, attribute))
 
 
 if _PY2:
@@ -455,3 +456,9 @@ if six.PY2:
 
 else:
     from functools import lru_cache  # noqa: F401
+
+
+if getattr(attr, "__version_info__", ()) >= (19, 2):
+    ATTRS_EQ_FIELD = "eq"
+else:
+    ATTRS_EQ_FIELD = "cmp"

src/_pytest/mark/structures.py

@@ -8,6 +8,7 @@ import attr
 import six
 
 from ..compat import ascii_escaped
+from ..compat import ATTRS_EQ_FIELD
 from ..compat import getfslineno
 from ..compat import MappingMixin
 from ..compat import NOTSET
@@ -377,7 +378,8 @@ class NodeKeywords(MappingMixin):
         return "<NodeKeywords for node %s>" % (self.node,)
 
 
-@attr.s(cmp=False, hash=False)
+# mypy cannot find this overload, remove when on attrs>=19.2
+@attr.s(hash=False, **{ATTRS_EQ_FIELD: False})  # type: ignore
 class NodeMarkers(object):
     """
     internal structure for storing marks belonging to a node

testing/test_assertion.py

@@ -14,6 +14,7 @@ import pytest
 from _pytest import outcomes
 from _pytest.assertion import truncate
 from _pytest.assertion import util
+from _pytest.compat import ATTRS_EQ_FIELD
 
 PY3 = sys.version_info >= (3, 0)
 
@@ -687,7 +688,7 @@ class TestAssert_reprcompare_attrsclass(object):
         @attr.s
         class SimpleDataObject(object):
             field_a = attr.ib()
-            field_b = attr.ib(cmp=False)
+            field_b = attr.ib(**{ATTRS_EQ_FIELD: False})
 
         left = SimpleDataObject(1, "b")
         right = SimpleDataObject(1, "b")