Add support to display field names in namedtuple diffs.

src/_pytest/assertion/util.py

@@ -110,6 +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
 
@@ -171,14 +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)):
-            explanation = _compare_eq_cls(left, right, verbose)
         elif verbose > 0:
             explanation = _compare_eq_verbose(left, right)
         if isiterable(left) and isiterable(right):
@@ -408,6 +418,10 @@ def _compare_eq_cls(left: Any, right: Any, verbose: int) -> List[str]:
     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 = []