Use ATTRS_EQ_FIELD for attrs 19.2 compat

Author: asottile

src/_pytest/assertion/util.py

@@ -8,7 +8,7 @@
 import _pytest._code
 from _pytest import outcomes
 from _pytest._io.saferepr import saferepr
-from _pytest.compat import attrs_has_eq
+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
@@ -113,18 +113,6 @@ def isattrs(obj):
     return getattr(obj, "__attrs_attrs__", None) is not None
 
 
-if attrs_has_eq:
-
-    def attrsfieldhaseq(a):
-        return a.eq
-
-
-else:
-
-    def attrsfieldhaseq(a):
-        return a.cmp
-
-
 def isiterable(obj):
     try:
         iter(obj)
@@ -388,7 +376,9 @@ 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 attrsfieldhaseq(field)]
+        fields_to_check = [
+            field.name for field in all_fields if getattr(field, ATTRS_EQ_FIELD)
+        ]
 
     same = []
     diff = []

src/_pytest/compat.py

@@ -356,8 +356,7 @@ def overload(f):  # noqa: F811
         return f
 
 
-attrs_has_eq = getattr(attr, "__version_info__", (0, 0)) >= (19, 2)
-if attrs_has_eq:
-    attrs_no_eq = {"eq": False}
+if getattr(attr, "__version_info__", ()) >= (19, 2):
+    ATTRS_EQ_FIELD = "eq"
 else:
-    attrs_no_eq = {"cmp": False}
+    ATTRS_EQ_FIELD = "cmp"

src/_pytest/mark/structures.py

@@ -8,7 +8,7 @@
 import attr
 
 from ..compat import ascii_escaped
-from ..compat import attrs_no_eq
+from ..compat import ATTRS_EQ_FIELD
 from ..compat import getfslineno
 from ..compat import NOTSET
 from _pytest.outcomes import fail
@@ -368,7 +368,8 @@ def __repr__(self):
         return "<NodeKeywords for node {}>".format(self.node)
 
 
-@attr.s(hash=False, **attrs_no_eq)  # type: ignore
+# mypy cannot find this overload, remove when on attrs>=19.2
+@attr.s(hash=False, **{ATTRS_EQ_FIELD: False})  # type: ignore
 class NodeMarkers:
     """
     internal structure for storing marks belonging to a node

testing/test_assertion.py

@@ -9,7 +9,7 @@
 from _pytest import outcomes
 from _pytest.assertion import truncate
 from _pytest.assertion import util
-from _pytest.compat import attrs_no_eq
+from _pytest.compat import ATTRS_EQ_FIELD
 
 
 def mock_config():
@@ -688,7 +688,7 @@ def test_attrs_with_attribute_comparison_off(self):
         @attr.s
         class SimpleDataObject:
             field_a = attr.ib()
-            field_b = attr.ib(**attrs_no_eq)
+            field_b = attr.ib(**{ATTRS_EQ_FIELD: False})
 
         left = SimpleDataObject(1, "b")
         right = SimpleDataObject(1, "b")