gh-96844: Improve error message of list.remove

Doc/library/doctest.rst

@@ -142,14 +142,14 @@
 Simple Usage: Checking Examples in Docstrings
 ---------------------------------------------
 
 The simplest way to start using doctest (but not necessarily the way you'll
 continue to do it) is to end each module :mod:`M` with::
 
    if __name__ == "__main__":
        import doctest
        doctest.testmod()
 
 :mod:`doctest` then examines docstrings in module :mod:`M`.
 
 Running the module as a script causes the examples in the docstrings to get
 executed and verified::
@@ -381,7 +381,7 @@
 What's the Execution Context?
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 By default, each time :mod:`doctest` finds a docstring to test, it uses a
 *shallow copy* of :mod:`M`'s globals, so that running tests doesn't change the
 module's real globals, and so that one test in :mod:`M` can't leave behind
 crumbs that accidentally allow another test to work.  This means examples can
@@ -409,10 +409,10 @@
    >>> [1, 2, 3].remove(42)
    Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
-   ValueError: list.remove(x): x not in list
+   ValueError: 42 is not in list
 
-That doctest succeeds if :exc:`ValueError` is raised, with the ``list.remove(x):
-x not in list`` detail as shown.
+That doctest succeeds if :exc:`ValueError` is raised, with the ``42 is not in list``
+detail as shown.
 
 The expected output for an exception must start with a traceback header, which
 may be either of the following two lines, indented the same as the first line of
@@ -935,7 +935,7 @@
    Optional argument *name* gives the name of the module; by default, or if
    ``None``, ``m.__name__`` is used.
 
    Optional argument *exclude_empty* defaults to false.  If true, objects for which
    no doctests are found are excluded from consideration. The default is a backward
    compatibility hack, so that code still using :meth:`doctest.master.summarize` in
    conjunction with :func:`testmod` continues to get output for objects with no
@@ -972,7 +972,7 @@
 Unittest API
 ------------
 
 As your collection of doctest'ed modules grows, you'll want a way to run all
 their doctests systematically.  :mod:`doctest` provides two functions that can
 be used to create :mod:`unittest` test suites from modules and text files
 containing doctests.  To integrate with :mod:`unittest` test discovery, include
@@ -995,7 +995,7 @@
    Convert doctest tests from one or more text files to a
    :class:`unittest.TestSuite`.
 
    The returned :class:`unittest.TestSuite` is to be run by the unittest framework
    and runs the interactive examples in each file.  If an example in any file
    fails, then the synthesized unit test fails, and a :exc:`failureException`
    exception is raised showing the name of the file containing the test and a
@@ -1061,7 +1061,7 @@
 
    Convert doctest tests for a module to a :class:`unittest.TestSuite`.
 
    The returned :class:`unittest.TestSuite` is to be run by the unittest framework
    and runs each doctest in the module.  If any of the doctests fail, then the
    synthesized unit test fails, and a :exc:`failureException` exception is raised
    showing the name of the file containing the test and a (sometimes approximate)
@@ -1091,7 +1091,7 @@
       contains no docstrings instead of raising :exc:`ValueError`.
 
 
 Under the covers, :func:`DocTestSuite` creates a :class:`unittest.TestSuite` out
 of :class:`doctest.DocTestCase` instances, and :class:`DocTestCase` is a
 subclass of :class:`unittest.TestCase`. :class:`DocTestCase` isn't documented
 here (it's an internal detail), but studying its code can answer questions about

Lib/test/test_xml_etree.py

@@ -328,7 +328,7 @@ def test_simpleops(self):
         self.serialize_check(element, '<tag key="value" />') # 5
         with self.assertRaises(ValueError) as cm:
             element.remove(subelement)
-        self.assertEqual(str(cm.exception), 'list.remove(x): x not in list')
+        self.assertIn('not in list', str(cm.exception))
         self.serialize_check(element, '<tag key="value" />') # 6
         element[0:0] = [subelement, subelement, subelement]
         self.serialize_check(element[1], '<subtag />')

Misc/NEWS.d/next/Core and Builtins/2023-07-06-00-35-44.gh-issue-96844.kwvoS-.rst

@@ -0,0 +1 @@
+Improve error message of :meth:`list.remove`. Patch by Dong-hee Na.

Objects/listobject.c

@@ -2694,7 +2694,7 @@ list_remove(PyListObject *self, PyObject *value)
         else if (cmp < 0)
             return NULL;
     }
-    PyErr_SetString(PyExc_ValueError, "list.remove(x): x not in list");
+    PyErr_Format(PyExc_ValueError, "%R is not in list", value);
     return NULL;
 }