Merge pull request #7553 from tirkarthi/namedtuple-diff

Add support to display field names in namedtuple diffs.

1 files changed, 18 insertions, 12 deletions

diff --git a/src/_pytest/assertion/util.py b/src/_pytest/assertion/util.py
index 08ff4eacd..da1ffd15e 100644
--- a/src/_pytest/assertion/util.py
+++ b/src/_pytest/assertion/util.py
@@ -9,7 +9,6 @@ from typing import List
 from typing import Mapping
 from typing import Optional
 from typing import Sequence
-from typing import Tuple
 
 import _pytest._code
 from _pytest import outcomes
@@ -111,6 +110,10 @@ def isset(x: Any) -> bool:
     return isinstance(x, (set, frozenset))
 
 
+def isnamedtuple(obj: Any) -> bool:
+    return isinstance(obj, tuple) and getattr(obj, "_fields", None) is not None
+
+
 def isdatacls(obj: Any) -> bool:
     return getattr(obj, "__dataclass_fields__", None) is not None
 
@@ -172,15 +175,20 @@ def _compare_eq_any(left: Any, right: Any, verbose: int = 0) -> List[str]:
     if istext(left) and istext(right):
         explanation = _diff_text(left, right, verbose)
     else:
-        if issequence(left) and issequence(right):
+        if type(left) == type(right) and (
+            isdatacls(left) or isattrs(left) or isnamedtuple(left)
+        ):
+            # Note: unlike dataclasses/attrs, namedtuples compare only the
+            # field values, not the type or field names. But this branch
+            # intentionally only handles the same-type case, which was often
+            # used in older code bases before dataclasses/attrs were available.
+            explanation = _compare_eq_cls(left, right, verbose)
+        elif issequence(left) and issequence(right):
             explanation = _compare_eq_sequence(left, right, verbose)
         elif isset(left) and isset(right):
             explanation = _compare_eq_set(left, right, verbose)
         elif isdict(left) and isdict(right):
             explanation = _compare_eq_dict(left, right, verbose)
-        elif type(left) == type(right) and (isdatacls(left) or isattrs(left)):
-            type_fn = (isdatacls, isattrs)
-            explanation = _compare_eq_cls(left, right, verbose, type_fn)
         elif verbose > 0:
             explanation = _compare_eq_verbose(left, right)
         if isiterable(left) and isiterable(right):
@@ -403,19 +411,17 @@ def _compare_eq_dict(
     return explanation
 
 
-def _compare_eq_cls(
-    left: Any,
-    right: Any,
-    verbose: int,
-    type_fns: Tuple[Callable[[Any], bool], Callable[[Any], bool]],
-) -> List[str]:
-    isdatacls, isattrs = type_fns
+def _compare_eq_cls(left: Any, right: Any, verbose: int) -> List[str]:
     if isdatacls(left):
         all_fields = left.__dataclass_fields__
         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 getattr(field, "eq")]
+    elif isnamedtuple(left):
+        fields_to_check = left._fields
+    else:
+        assert False
 
     indent = "  "
     same = []