From 0ccb57904fea0a179ff4c2ae8195fc65d08d10eb Mon Sep 17 00:00:00 2001
From: Ran Benita <ran@unusedvar.com>
Date: Sun, 1 Jun 2025 22:14:02 +0300
Subject: [PATCH 1/2] python: a bit nicer error on duplicate parametrization

Raising `ValueError` dumps all of the internal stacktrace to the user,
which is not helpful. Raising `CollectError` is handled specially to
just print the message.

It would be nice to show source location or such - maybe another time.

Fix #13457
---
 changelog/13457.improvement.rst |  1 +
 src/_pytest/python.py           |  4 +++-
 testing/python/metafunc.py      | 12 ++++++++----
 3 files changed, 12 insertions(+), 5 deletions(-)
 create mode 100644 changelog/13457.improvement.rst

diff --git a/changelog/13457.improvement.rst b/changelog/13457.improvement.rst
new file mode 100644
index 00000000000..3937384b322
--- /dev/null
+++ b/changelog/13457.improvement.rst
@@ -0,0 +1 @@
+The error message about duplicate parametrization no longer displays an internal stack trace.
diff --git a/src/_pytest/python.py b/src/_pytest/python.py
index 1e085a80529..02b71767dc2 100644
--- a/src/_pytest/python.py
+++ b/src/_pytest/python.py
@@ -1079,7 +1079,9 @@ def setmulti(
         arg2scope = dict(self._arg2scope)
         for arg, val in zip(argnames, valset):
             if arg in params:
-                raise ValueError(f"duplicate parametrization of {arg!r}")
+                raise nodes.Collector.CollectError(
+                    f"duplicate parametrization of {arg!r}"
+                )
             params[arg] = val
             indices[arg] = param_index
             arg2scope[arg] = scope
diff --git a/testing/python/metafunc.py b/testing/python/metafunc.py
index e8b345aecc6..7ae26de3a18 100644
--- a/testing/python/metafunc.py
+++ b/testing/python/metafunc.py
@@ -82,11 +82,15 @@ def func(x, y):
 
         metafunc = self.Metafunc(func)
         metafunc.parametrize("x", [1, 2])
-        pytest.raises(ValueError, lambda: metafunc.parametrize("x", [5, 6]))
-        pytest.raises(ValueError, lambda: metafunc.parametrize("x", [5, 6]))
+        with pytest.raises(pytest.Collector.CollectError):
+            metafunc.parametrize("x", [5, 6])
+        with pytest.raises(pytest.Collector.CollectError):
+            metafunc.parametrize("x", [5, 6])
         metafunc.parametrize("y", [1, 2])
-        pytest.raises(ValueError, lambda: metafunc.parametrize("y", [5, 6]))
-        pytest.raises(ValueError, lambda: metafunc.parametrize("y", [5, 6]))
+        with pytest.raises(pytest.Collector.CollectError):
+            metafunc.parametrize("y", [5, 6])
+        with pytest.raises(pytest.Collector.CollectError):
+            metafunc.parametrize("y", [5, 6])
 
         with pytest.raises(TypeError, match="^ids must be a callable or an iterable$"):
             metafunc.parametrize("y", [5, 6], ids=42)  # type: ignore[arg-type]

From 30407eb7613bcafd8651beb047a8a2fc215409ab Mon Sep 17 00:00:00 2001
From: Ran Benita <ran@unusedvar.com>
Date: Mon, 2 Jun 2025 11:22:07 +0300
Subject: [PATCH 2/2] python: pinpoint nodeid in a couple of parametrization
 errors

---
 src/_pytest/python.py | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/_pytest/python.py b/src/_pytest/python.py
index 02b71767dc2..82aab85a300 100644
--- a/src/_pytest/python.py
+++ b/src/_pytest/python.py
@@ -1073,6 +1073,7 @@ def setmulti(
         marks: Iterable[Mark | MarkDecorator],
         scope: Scope,
         param_index: int,
+        nodeid: str,
     ) -> CallSpec2:
         params = self.params.copy()
         indices = self.indices.copy()
@@ -1080,7 +1081,7 @@ def setmulti(
         for arg, val in zip(argnames, valset):
             if arg in params:
                 raise nodes.Collector.CollectError(
-                    f"duplicate parametrization of {arg!r}"
+                    f"{nodeid}: duplicate parametrization of {arg!r}"
                 )
             params[arg] = val
             indices[arg] = param_index
@@ -1235,6 +1236,8 @@ def parametrize(
             It will also override any fixture-function defined scope, allowing
             to set a dynamic scope using test context or configuration.
         """
+        nodeid = self.definition.nodeid
+
         argnames, parametersets = ParameterSet._for_parametrize(
             argnames,
             argvalues,
@@ -1246,7 +1249,7 @@ def parametrize(
 
         if "request" in argnames:
             fail(
-                "'request' is a reserved name and cannot be used in @pytest.mark.parametrize",
+                f"{nodeid}: 'request' is a reserved name and cannot be used in @pytest.mark.parametrize",
                 pytrace=False,
             )
 
@@ -1341,6 +1344,7 @@ def parametrize(
                     marks=param_set.marks,
                     scope=scope_,
                     param_index=param_index,
+                    nodeid=nodeid,
                 )
                 newcalls.append(newcallspec)
         self._calls = newcalls