feat: add cli, ini option skips pytest internal logic of id generation and raise error

Author: gomri15

changelog/13737.feature.rst

@@ -0,0 +1,4 @@
+Added the ``--require-unique-paramset-ids`` flag to pytest.
+
+When passed, this flag causes pytest to raise an exception upon detection of non-unique parameter set IDs,
+rather than attempting to generate them automatically.

doc/en/reference/reference.rst

@@ -2082,6 +2082,30 @@ passed multiple times. The expected format is ``name=value``. For example::
  [pytest]
  xfail_strict = True
 
+.. confval:: require_unique_paramset_ids
+
+ When passed, this flag causes pytest to raise an exception upon detection of non-unique parameter set IDs,
+ rather than attempting to generate them automatically.
+
+ Can be overridden by `--require-unique-paramset-ids`.
+
+ .. code-block:: ini
+
+ [pytest]
+ require_unique_paramset_ids = True
+
+ .. code-block:: python
+
+ import pytest
+
+
+ @pytest.mark.parametrize("x", [1, 2], ids=["a", "a"])
+ def test_example(x):
+ assert x in (1, 2)
+
+ will raise an exception due to the duplicate IDs "a".
+ when normal pytest behavior would be to handle this by generating unique IDs like "a-0", "a-1".
+
 
 .. _`command-line-flags`:
 
@@ -2239,6 +2263,11 @@ All the command-line flags can be obtained by running ``pytest --help``::
  --doctest-continue-on-failure
  For a given doctest, continue to run after the first
  failure
+ --require-unique-paramset-ids
+ If pytest collects test ids with non-unique names, raise an
+ error rather than handling it.
+ Useful if you collect in one process,
+ and then execute tests in independent workers.
 
  test session debugging and configuration:
  -c, --config-file FILE

src/_pytest/main.py

@@ -90,6 +90,21 @@ def pytest_addoption(parser: Parser) -> None:
  action="store_true",
  help="(Deprecated) alias to --strict-markers",
  )
+ group.addoption(
+ "--require-unique-paramset-ids",
+ action="store_true",
+ default=False,
+ help="When passed, this flag causes pytest to raise an exception upon detection of non-unique parameter set IDs"
+ "rather than attempting to generate them automatically.",
+ )
+
+ parser.addini(
+ "require_unique_paramset_ids",
+ type="bool",
+ default=False,
+ help="When passed, this flag causes pytest to raise an exception upon detection of non-unique parameter set IDs"
+ "rather than attempting to generate them automatically.",
+ )
 
  group = parser.getgroup("pytest-warnings")
  group.addoption(

src/_pytest/python.py

@@ -50,6 +50,7 @@
 from _pytest.config import Config
 from _pytest.config import hookimpl
 from _pytest.config.argparsing import Parser
+from _pytest.config.exceptions import UsageError
 from _pytest.deprecated import check_ispytest
 from _pytest.fixtures import FixtureDef
 from _pytest.fixtures import FixtureRequest
@@ -902,6 +903,23 @@ def make_unique_parameterset_ids(self) -> list[str | _HiddenParam]:
  resolved_ids = list(self._resolve_ids())
  # All IDs must be unique!
  if len(resolved_ids) != len(set(resolved_ids)):
+ if self._require_unique_ids_enabled():
+ duplicate_indexs = defaultdict(list)
+ for i, val in enumerate(resolved_ids):
+ duplicate_indexs[val].append(i)
+
+ # Keep only duplicates
+ duplicates = {k: v for k, v in duplicate_indexs.items() if len(v) > 1}
+ raise UsageError(f"""
+ Because --require-unique-paramset-ids given, pytest won't
+ attempt to generate unique IDs for parameter sets.
+ argument values: {self.parametersets}
+ argument names: {self.argnames}
+ function name: {self.func_name}
+ test name: {self.nodeid}
+ resolved (with non-unique) IDs: {resolved_ids}
+ duplicates: {duplicates}
+ """)
  # Record the number of occurrences of each ID.
  id_counts = Counter(resolved_ids)
  # Map the ID to its next suffix.
@@ -925,6 +943,14 @@ def make_unique_parameterset_ids(self) -> list[str | _HiddenParam]:
  )
  return resolved_ids
 
+ def _require_unique_ids_enabled(self) -> bool:
+ if self.config:
+ cli_value = self.config.getoption("require_unique_paramset_ids")
+ if cli_value:
+ return bool(cli_value)
+ return bool(self.config.getini("require_unique_paramset_ids"))
+ return False
+
  def _resolve_ids(self) -> Iterable[str | _HiddenParam]:
  """Resolve IDs for all ParameterSets (may contain duplicates)."""
  for idx, parameterset in enumerate(self.parametersets):

testing/test_collection.py

@@ -5,6 +5,7 @@
 from pathlib import Path
 from pathlib import PurePath
 import pprint
+import re
 import shutil
 import sys
 import tempfile
@@ -2702,3 +2703,73 @@ def test_1(): pass
  ],
  consecutive=True,
  )
+
+
+class TestRequireUniqueParamsetIds:
+ CASES = [
+ ("[(1, 1), (1, 1)]", {"1-1": [0, 1]}),
+ ("[(1, 1), (1, 2), (1, 1)]", {"1-1": [0, 2]}),
+ ("[(1, 1), (2, 2), (1, 1)]", {"1-1": [0, 2]}),
+ ("[(1, 1), (2, 2), (1, 2), (2, 1), (1, 1)]", {"1-1": [0, 4]}),
+ ]
+
+ @staticmethod
+ def _make_testfile(pytester: Pytester, parametrize_args: str) -> None:
+ pytester.makepyfile(
+ f"""
+ import pytest
+
+ @pytest.mark.parametrize('y, x', {parametrize_args})
+ def test1(y, x):
+ pass
+ """
+ )
+
+ @staticmethod
+ def _fnmatch_escape_repr(obj) -> str:
+ return re.sub(r"[*?[\]]", (lambda m: f"[{m.group()}]"), repr(obj))
+
+ def _assert_duplicate_msg(self, result, expected_indices):
+ # Collection errors usually go to stdout; fall back to stderr just in case.
+ stream = result.stdout
+ stream.fnmatch_lines(
+ [
+ "E*Because --require-unique-paramset-ids given, pytest won't",
+ "E*attempt to generate unique IDs for parameter sets.",
+ "E*argument names: [[]'y', 'x'[]]",
+ "E*function name: test1",
+ "E*test name: *::test1",
+ f"E*duplicates: {self._fnmatch_escape_repr(expected_indices)}",
+ ]
+ )
+ assert result.ret != 0
+
+ @pytest.mark.parametrize("parametrize_args, expected_indices", CASES)
+ def test_cli_enables(self, pytester: Pytester, parametrize_args, expected_indices):
+ self._make_testfile(pytester, parametrize_args)
+ result = pytester.runpytest("--require-unique-paramset-ids")
+ self._assert_duplicate_msg(result, expected_indices)
+
+ @pytest.mark.parametrize("parametrize_args, expected_indices", CASES)
+ def test_ini_enables(self, pytester: Pytester, parametrize_args, expected_indices):
+ pytester.makeini(
+ """
+ [pytest]
+ require_unique_paramset_ids = true
+ """
+ )
+ self._make_testfile(pytester, parametrize_args)
+ result = pytester.runpytest()
+ self._assert_duplicate_msg(result, expected_indices)
+
+ def test_cli_overrides_ini_false(self, pytester: Pytester):
+ """CLI True should override ini False."""
+ pytester.makeini(
+ """
+ [pytest]
+ require_unique_paramset_ids = false
+ """
+ )
+ self._make_testfile(pytester, "[(1,1), (1,1)]")
+ result = pytester.runpytest("--require-unique-paramset-ids")
+ self._assert_duplicate_msg(result, {"1-1": [0, 1]})