From 4c0540e098509d77df1fca5315a06044d11b2410 Mon Sep 17 00:00:00 2001
From: Brendan Cazier <520246+cazier@users.noreply.github.com>
Date: Sun, 9 Nov 2025 14:58:50 +0000
Subject: [PATCH 1/4] Add an ids attribute to callspec with parametrization
 names

---
 src/_pytest/python.py | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/_pytest/python.py b/src/_pytest/python.py
index 257dd78f462..1a0bc4398fb 100644
--- a/src/_pytest/python.py
+++ b/src/_pytest/python.py
@@ -1113,6 +1113,8 @@ class CallSpec2:
     _idlist: Sequence[str] = dataclasses.field(default_factory=tuple)
     # Marks which will be applied to the item.
     marks: list[Mark] = dataclasses.field(default_factory=list)
+    # Parametrization mapping for each argname to an ID.
+    ids: dict[str | tuple[str, ...], str] = dataclasses.field(default_factory=dict)
 
     def setmulti(
         self,
@@ -1142,6 +1144,14 @@ def setmulti(
             _arg2scope=arg2scope,
             _idlist=self._idlist if id is HIDDEN_PARAM else [*self._idlist, id],
             marks=[*self.marks, *normalize_mark_list(marks)],
+            ids=self.ids
+            if id is HIDDEN_PARAM
+            else {
+                **self.ids,
+                _argnames[0]
+                if len(_argnames := tuple(argnames)) == 1
+                else _argnames: id,
+            },
         )
 
     def getparam(self, name: str) -> object:

From 9515bdff35c0b6464e5601afdd0a192d28ad868c Mon Sep 17 00:00:00 2001
From: Brendan Cazier <520246+cazier@users.noreply.github.com>
Date: Sun, 9 Nov 2025 15:11:21 +0000
Subject: [PATCH 2/4] Adding tests for new ids attribute

---
 testing/test_mark.py | 44 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/testing/test_mark.py b/testing/test_mark.py
index 8d76ea310eb..f6c5d614940 100644
--- a/testing/test_mark.py
+++ b/testing/test_mark.py
@@ -1090,6 +1090,50 @@ def test_parameterset_for_parametrize_bad_markname(pytester: Pytester) -> None:
         test_parameterset_for_parametrize_marks(pytester, "bad")
 
 
+def test_parametrization_callspec_ids(pytester: Pytester):
+    pytester.makepyfile(
+        """
+import pytest
+
+class CustomClass:
+    pass
+
+def custom_function():
+    return None
+
+all_ids = [
+    {("tuple_one", "tuple_two"): "t1a-t2a", "id_function": "11", "id_explicit": "one", "name": "first"},
+    {("tuple_one", "tuple_two"): "t1a-t2a", "id_function": "11", "id_explicit": "one", "name": "2"},
+    {("tuple_one", "tuple_two"): "t1a-t2a", "id_function": "11", "id_explicit": "one", "name": "3.5"},
+    {("tuple_one", "tuple_two"): "t1a-t2a", "id_function": "11", "id_explicit": "one", "name": "True"},
+    {("tuple_one", "tuple_two"): "t1a-t2a", "id_function": "11", "id_explicit": "one", "name": "<lambda>"},
+    {("tuple_one", "tuple_two"): "t1a-t2a", "id_function": "11", "id_explicit": "one", "name": "CustomClass"},
+    {("tuple_one", "tuple_two"): "t1a-t2a", "id_function": "11", "id_explicit": "one", "name": "custom_function"},
+    {("tuple_one", "tuple_two"): "t1b-t2b", "id_function": "11", "id_explicit": "one", "name": "first"},
+    {("tuple_one", "tuple_two"): "t1b-t2b", "id_function": "11", "id_explicit": "one", "name": "2"},
+    {("tuple_one", "tuple_two"): "t1b-t2b", "id_function": "11", "id_explicit": "one", "name": "3.5"},
+    {("tuple_one", "tuple_two"): "t1b-t2b", "id_function": "11", "id_explicit": "one", "name": "True"},
+    {("tuple_one", "tuple_two"): "t1b-t2b", "id_function": "11", "id_explicit": "one", "name": "<lambda>"},
+    {("tuple_one", "tuple_two"): "t1b-t2b", "id_function": "11", "id_explicit": "one", "name": "CustomClass"},
+    {("tuple_one", "tuple_two"): "t1b-t2b", "id_function": "11", "id_explicit": "one", "name": "custom_function"}
+]
+
+@pytest.mark.parametrize("name", ("first", 2, 3.5, True, lambda k: k, CustomClass, custom_function))
+@pytest.mark.parametrize("id_explicit", (1,), ids=("one",))
+@pytest.mark.parametrize("id_function", (1,), ids=lambda k: f"{k}{k}")
+@pytest.mark.parametrize(("tuple_one", "tuple_two"), (("t1a", "t2a"), ("t1b", "t2b")))
+def test_more(name, id_explicit, id_function, tuple_one, tuple_two, request):
+    ids = request.node.callspec.ids
+    assert ids in all_ids
+"""
+    )
+
+    reprec = pytester.inline_run()
+    passed, skipped, failed = reprec.countoutcomes()
+    assert passed == 14
+    assert skipped == failed == 0
+
+
 def test_mark_expressions_no_smear(pytester: Pytester) -> None:
     pytester.makepyfile(
         """

From 56e686872767f1b3ba3450635fbfd633a9e0f696 Mon Sep 17 00:00:00 2001
From: Brendan Cazier <520246+cazier@users.noreply.github.com>
Date: Sun, 9 Nov 2025 15:45:50 +0000
Subject: [PATCH 3/4] Bookkeeping

---
 AUTHORS | 1 +
 1 file changed, 1 insertion(+)

diff --git a/AUTHORS b/AUTHORS
index 83509281035..ad68b12bee7 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -70,6 +70,7 @@ Benjamin Schubert
 Bernard Pratz
 Bo Wu
 Bob Ippolito
+Brendan Cazier
 Brian Dorsey
 Brian Larsen
 Brian Maissy

From 2b7719a897d9ee55cbd10d1dd4d65f6aa7b6e562 Mon Sep 17 00:00:00 2001
From: Brendan Cazier <520246+cazier@users.noreply.github.com>
Date: Sun, 9 Nov 2025 16:01:20 +0000
Subject: [PATCH 4/4] Adding changelog

---
 changelog/13907.improvement.rst | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 changelog/13907.improvement.rst

diff --git a/changelog/13907.improvement.rst b/changelog/13907.improvement.rst
new file mode 100644
index 00000000000..d96eefaeffe
--- /dev/null
+++ b/changelog/13907.improvement.rst
@@ -0,0 +1 @@
+Added a new attribute to the Callspec2 class with the stringified (either automatically or with an explicit `ids` parameter) ID of parametrization values.