From 310255e0b44b7bb01f41a67a41ad450ad227849d Mon Sep 17 00:00:00 2001
From: Martin Imre <martinimre25@gmail.com>
Date: Thu, 20 Mar 2025 17:15:32 +0100
Subject: [PATCH 1/6] feat(config): Allow ranges in envlist

Implements #3502. Now it is possible to use ranges within the {} of an
env specifier such as py3{10-13}.
I chose to implement it as a pre-processing string replacement that just
replaces the range with a literal enumeration of the range members.
This is mainly to avoid more in-depth handling of these ranges when it
coto generative environment lists.

Also moves CircularChainError from `of_type` to `types` to avoid a
circular import error. (kinda ironic :D)
---
 docs/changelog/3502.feature.rst        |  1 +
 docs/config.rst                        | 39 +++++++++++++----
 src/tox/config/loader/replacer.py      | 17 +++++++-
 src/tox/config/loader/str_convert.py   |  2 +
 src/tox/config/of_type.py              |  5 +--
 src/tox/config/source/ini_section.py   |  3 +-
 src/tox/config/types.py                |  4 ++
 tests/config/loader/ini/test_factor.py | 60 ++++++++++++++++++++++++++
 8 files changed, 116 insertions(+), 15 deletions(-)
 create mode 100644 docs/changelog/3502.feature.rst

diff --git a/docs/changelog/3502.feature.rst b/docs/changelog/3502.feature.rst
new file mode 100644
index 0000000000..85b6373bb3
--- /dev/null
+++ b/docs/changelog/3502.feature.rst
@@ -0,0 +1 @@
+Add ranges to generative environments such as py3{10-13}. - by :user:`mimre25`
diff --git a/docs/config.rst b/docs/config.rst
index fb099c3d9d..eb367a3a25 100644
--- a/docs/config.rst
+++ b/docs/config.rst
@@ -1563,7 +1563,7 @@ If you have a large matrix of dependencies, python versions and/or environments
 .. code-block:: ini
 
     [tox]
-    env_list = py{311,310,39}-django{41,40}-{sqlite,mysql}
+    env_list = py3{9-11}-django{41,40}-{sqlite,mysql}
 
     [testenv]
     deps =
@@ -1582,24 +1582,45 @@ This will generate the following tox environments:
 
     > tox l
     default environments:
-    py311-django41-sqlite -> [no description]
-    py311-django41-mysql  -> [no description]
-    py311-django40-sqlite -> [no description]
-    py311-django40-mysql  -> [no description]
-    py310-django41-sqlite -> [no description]
-    py310-django41-mysql  -> [no description]
-    py310-django40-sqlite -> [no description]
-    py310-django40-mysql  -> [no description]
     py39-django41-sqlite  -> [no description]
     py39-django41-mysql   -> [no description]
     py39-django40-sqlite  -> [no description]
     py39-django40-mysql   -> [no description]
+    py310-django41-sqlite -> [no description]
+    py310-django41-mysql  -> [no description]
+    py310-django40-sqlite -> [no description]
+    py310-django40-mysql  -> [no description]
+    py311-django41-sqlite -> [no description]
+    py311-django41-mysql  -> [no description]
+    py311-django40-sqlite -> [no description]
+    py311-django40-mysql  -> [no description]
+
+Both enumerations (`{1,2,3}`) and ranges (`{1-3}`) are supported, and can be mixed together:
+.. code-block:: ini
+
+    [tox]
+    env_list = py3{8-10, 11, 13-14}
+
+will create the following envs:
+.. code-block:: shell
+
+    > tox l
+    default environments:
+    py38  -> [no description]
+    py39  -> [no description]
+    py310 -> [no description]
+    py311 -> [no description]
+    py313 -> [no description]
+    py314 -> [no description]
+
+
 
 Generative section names
 ~~~~~~~~~~~~~~~~~~~~~~~~
 
 Suppose you have some binary packages, and need to run tests both in 32 and 64 bits. You also want an environment to
 create your virtual env for the developers.
+This also supports ranges in the same way as generative environment lists.
 
 .. code-block:: ini
 
diff --git a/src/tox/config/loader/replacer.py b/src/tox/config/loader/replacer.py
index 05e3c060b5..148e8e8384 100644
--- a/src/tox/config/loader/replacer.py
+++ b/src/tox/config/loader/replacer.py
@@ -4,11 +4,12 @@
 
 import logging
 import os
+import re
 import sys
 from abc import ABC, abstractmethod
 from typing import TYPE_CHECKING, Any, Final, Sequence, Union
 
-from tox.config.of_type import CircularChainError
+from tox.config.types import CircularChainError
 from tox.execute.request import shell_cmd
 
 if TYPE_CHECKING:
@@ -287,9 +288,23 @@ def replace_tty(args: list[str]) -> str:
     return (args[0] if len(args) > 0 else "") if sys.stdout.isatty() else args[1] if len(args) > 1 else ""
 
 
+def expand_ranges(value: str) -> str:
+    """Expand ranges in env expressions, eg py3{10-13} -> "py3{10,11,12,13}"""
+    matches = re.findall(r"((\d+)-(\d+)|\d+)(?:,|})", value)
+    for src, start_, end_ in matches:
+        if src and start_ and end_:
+            start = int(start_)
+            end = int(end_)
+            direction = 1 if start < end else -1
+            expansion = ",".join(str(x) for x in range(start, end + direction, direction))
+            value = value.replace(src, expansion, 1)
+    return value
+
+
 __all__ = [
     "MatchExpression",
     "MatchRecursionError",
+    "expand_ranges",
     "find_replace_expr",
     "load_posargs",
     "replace",
diff --git a/src/tox/config/loader/str_convert.py b/src/tox/config/loader/str_convert.py
index 65dd46dad7..e7878e5fe5 100644
--- a/src/tox/config/loader/str_convert.py
+++ b/src/tox/config/loader/str_convert.py
@@ -10,6 +10,7 @@
 from typing import TYPE_CHECKING, Any, Iterator
 
 from tox.config.loader.convert import Convert
+from tox.config.loader.replacer import expand_ranges
 from tox.config.types import Command, EnvList
 
 if TYPE_CHECKING:
@@ -113,6 +114,7 @@ def to_command(value: str) -> Command | None:
     def to_env_list(value: str) -> EnvList:
         from tox.config.loader.ini.factor import extend_factors  # noqa: PLC0415
 
+        value = expand_ranges(value)
         elements = list(chain.from_iterable(extend_factors(expr) for expr in value.split("\n")))
         return EnvList(elements)
 
diff --git a/src/tox/config/of_type.py b/src/tox/config/of_type.py
index d31922f6c2..4d49d16ef3 100644
--- a/src/tox/config/of_type.py
+++ b/src/tox/config/of_type.py
@@ -7,16 +7,13 @@
 from typing import TYPE_CHECKING, Callable, Generic, Iterable, TypeVar, cast
 
 from tox.config.loader.api import ConfigLoadArgs, Loader
+from tox.config.types import CircularChainError
 
 if TYPE_CHECKING:
     from tox.config.loader.convert import Factory
     from tox.config.main import Config  # pragma: no cover
 
 
-class CircularChainError(ValueError):
-    """circular chain in config"""
-
-
 T = TypeVar("T")
 V = TypeVar("V")
 
diff --git a/src/tox/config/source/ini_section.py b/src/tox/config/source/ini_section.py
index d7d26720fc..548a6bab73 100644
--- a/src/tox/config/source/ini_section.py
+++ b/src/tox/config/source/ini_section.py
@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 from tox.config.loader.ini.factor import extend_factors
+from tox.config.loader.replacer import expand_ranges
 from tox.config.loader.section import Section
 
 
@@ -15,7 +16,7 @@ def is_test_env(self) -> bool:
 
     @property
     def names(self) -> list[str]:
-        return list(extend_factors(self.name))
+        return list(extend_factors(expand_ranges(self.name)))
 
 
 TEST_ENV_PREFIX = "testenv"
diff --git a/src/tox/config/types.py b/src/tox/config/types.py
index 8d1300aa42..42c2c48149 100644
--- a/src/tox/config/types.py
+++ b/src/tox/config/types.py
@@ -6,6 +6,10 @@
 from tox.execute.request import shell_cmd
 
 
+class CircularChainError(ValueError):
+    """circular chain in config"""
+
+
 class Command:  # noqa: PLW1641
     """A command to execute."""
 
diff --git a/tests/config/loader/ini/test_factor.py b/tests/config/loader/ini/test_factor.py
index b73abd03be..ebc861dfd8 100644
--- a/tests/config/loader/ini/test_factor.py
+++ b/tests/config/loader/ini/test_factor.py
@@ -178,6 +178,54 @@ def test_factor_config_no_env_list_creates_env(tox_ini_conf: ToxIniCreator) -> N
     assert list(config) == ["py37-django15", "py37-django16", "py36"]
 
 
+@pytest.mark.parametrize(
+    ("env_list", "expected_envs"),
+    [
+        ("py3{10-13}", ["py310", "py311", "py312", "py313"]),
+        ("py3{10-11},a", ["py310", "py311", "a"]),
+        ("py3{10-11},a{1-2}", ["py310", "py311", "a1", "a2"]),
+        ("py3{10-12,14}", ["py310", "py311", "py312", "py314"]),
+        ("py3{8-10,12,14-16}", ["py38", "py39", "py310", "py312", "py314", "py315", "py316"]),
+        (
+            "py3{10-11}-django1.{3-5}",
+            [
+                "py310-django1.3",
+                "py310-django1.4",
+                "py310-django1.5",
+                "py311-django1.3",
+                "py311-django1.4",
+                "py311-django1.5",
+            ],
+        ),
+        (
+            "py3{10-11, 13}-django1.{3-4, 6}",
+            [
+                "py310-django1.3",
+                "py310-django1.4",
+                "py310-django1.6",
+                "py311-django1.3",
+                "py311-django1.4",
+                "py311-django1.6",
+                "py313-django1.3",
+                "py313-django1.4",
+                "py313-django1.6",
+            ],
+        ),
+        ("py3{10-11},a{1-2}-b{3-4}", ["py310", "py311", "a1-b3", "a1-b4", "a2-b3", "a2-b4"]),
+        ("py3{13-11}", ["py313", "py312", "py311"]),
+    ],
+)
+def test_env_list_expands_ranges(env_list: str, expected_envs: list[str], tox_ini_conf: ToxIniCreator) -> None:
+    config = tox_ini_conf(
+        f"""
+        [tox]
+        env_list = {env_list}
+        """
+    )
+
+    assert list(config) == expected_envs
+
+
 @pytest.mark.parametrize(
     ("env", "result"),
     [
@@ -202,6 +250,18 @@ def test_ini_loader_raw_with_factors(
     assert outcome == result
 
 
+def test_generative_section_name_with_ranges(tox_ini_conf: ToxIniCreator) -> None:
+    config = tox_ini_conf(
+        """
+        [testenv:py3{11-13}-{black,lint}]
+        deps-x =
+            black: black
+            lint: flake8
+        """,
+    )
+    assert list(config) == ["py311-black", "py311-lint", "py312-black", "py312-lint", "py313-black", "py313-lint"]
+
+
 def test_generative_section_name(tox_ini_conf: ToxIniCreator) -> None:
     config = tox_ini_conf(
         """

From d535b707e4246ce52c2a354711ec9b701eb24136 Mon Sep 17 00:00:00 2001
From: Martin Imre <martinimre25@gmail.com>
Date: Sun, 23 Mar 2025 14:10:53 +0100
Subject: [PATCH 2/6] fixup! feat(config): Allow ranges in envlist

---
 src/tox/config/loader/ini/factor.py    | 2 +-
 tests/config/loader/ini/test_factor.py | 7 +++++++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/tox/config/loader/ini/factor.py b/src/tox/config/loader/ini/factor.py
index 1bb639bbf3..45e63e5b73 100644
--- a/src/tox/config/loader/ini/factor.py
+++ b/src/tox/config/loader/ini/factor.py
@@ -66,7 +66,7 @@ def find_factor_groups(value: str) -> Iterator[list[tuple[str, bool]]]:
         yield result
 
 
-_FACTOR_RE = re.compile(r"!?[\w._][\w._-]*")
+_FACTOR_RE = re.compile(r"(?:!?[\w._][\w._-]*|^$)")
 
 
 def expand_env_with_negation(value: str) -> Iterator[str]:
diff --git a/tests/config/loader/ini/test_factor.py b/tests/config/loader/ini/test_factor.py
index ebc861dfd8..b86c4a129d 100644
--- a/tests/config/loader/ini/test_factor.py
+++ b/tests/config/loader/ini/test_factor.py
@@ -213,6 +213,13 @@ def test_factor_config_no_env_list_creates_env(tox_ini_conf: ToxIniCreator) -> N
         ),
         ("py3{10-11},a{1-2}-b{3-4}", ["py310", "py311", "a1-b3", "a1-b4", "a2-b3", "a2-b4"]),
         ("py3{13-11}", ["py313", "py312", "py311"]),
+        ("py3{-11}", ["py3-11"]),
+        ("foo{11-}", ["foo11-"]),
+        ("foo{a-}", ["fooa-"]),
+        ("foo{-a}", ["foo-a"]),
+        ("foo{a-11}", ["fooa-11"]),
+        ("foo{13-a}", ["foo13-a"]),
+        ("foo{a-b}", ["fooa-b"]),
     ],
 )
 def test_env_list_expands_ranges(env_list: str, expected_envs: list[str], tox_ini_conf: ToxIniCreator) -> None:

From 8f086c81ff0457b49f5c04cd01466821b05bb2b8 Mon Sep 17 00:00:00 2001
From: Martin Imre <martinimre25@gmail.com>
Date: Sun, 23 Mar 2025 16:23:23 +0100
Subject: [PATCH 3/6] fixup! feat(config): Allow ranges in envlist

---
 src/tox/config/loader/ini/factor.py  | 12 ++++++++++++
 src/tox/config/loader/replacer.py    | 15 ---------------
 src/tox/config/loader/str_convert.py |  2 +-
 src/tox/config/source/ini_section.py |  3 +--
 4 files changed, 14 insertions(+), 18 deletions(-)

diff --git a/src/tox/config/loader/ini/factor.py b/src/tox/config/loader/ini/factor.py
index 45e63e5b73..d10dd28d8d 100644
--- a/src/tox/config/loader/ini/factor.py
+++ b/src/tox/config/loader/ini/factor.py
@@ -92,10 +92,22 @@ def name_with_negate(factor: str) -> tuple[str, bool]:
 def is_negated(factor: str) -> bool:
     return factor.startswith("!")
 
+def expand_ranges(value: str) -> str:
+    """Expand ranges in env expressions, eg py3{10-13} -> "py3{10,11,12,13}"""
+    matches = re.findall(r"((\d+)-(\d+)|\d+)(?:,|})", value)
+    for src, start_, end_ in matches:
+        if src and start_ and end_:
+            start = int(start_)
+            end = int(end_)
+            direction = 1 if start < end else -1
+            expansion = ",".join(str(x) for x in range(start, end + direction, direction))
+            value = value.replace(src, expansion, 1)
+    return value
 
 __all__ = (
     "expand_factors",
     "extend_factors",
     "filter_for_env",
     "find_envs",
+    "expand_ranges",
 )
diff --git a/src/tox/config/loader/replacer.py b/src/tox/config/loader/replacer.py
index 148e8e8384..d1ab6a9e38 100644
--- a/src/tox/config/loader/replacer.py
+++ b/src/tox/config/loader/replacer.py
@@ -287,24 +287,9 @@ def replace_env(conf: Config | None, args: list[str], conf_args: ConfigLoadArgs)
 def replace_tty(args: list[str]) -> str:
     return (args[0] if len(args) > 0 else "") if sys.stdout.isatty() else args[1] if len(args) > 1 else ""
 
-
-def expand_ranges(value: str) -> str:
-    """Expand ranges in env expressions, eg py3{10-13} -> "py3{10,11,12,13}"""
-    matches = re.findall(r"((\d+)-(\d+)|\d+)(?:,|})", value)
-    for src, start_, end_ in matches:
-        if src and start_ and end_:
-            start = int(start_)
-            end = int(end_)
-            direction = 1 if start < end else -1
-            expansion = ",".join(str(x) for x in range(start, end + direction, direction))
-            value = value.replace(src, expansion, 1)
-    return value
-
-
 __all__ = [
     "MatchExpression",
     "MatchRecursionError",
-    "expand_ranges",
     "find_replace_expr",
     "load_posargs",
     "replace",
diff --git a/src/tox/config/loader/str_convert.py b/src/tox/config/loader/str_convert.py
index e7878e5fe5..248afe2685 100644
--- a/src/tox/config/loader/str_convert.py
+++ b/src/tox/config/loader/str_convert.py
@@ -10,7 +10,7 @@
 from typing import TYPE_CHECKING, Any, Iterator
 
 from tox.config.loader.convert import Convert
-from tox.config.loader.replacer import expand_ranges
+from tox.config.loader.ini.factor import expand_ranges
 from tox.config.types import Command, EnvList
 
 if TYPE_CHECKING:
diff --git a/src/tox/config/source/ini_section.py b/src/tox/config/source/ini_section.py
index 548a6bab73..175444693a 100644
--- a/src/tox/config/source/ini_section.py
+++ b/src/tox/config/source/ini_section.py
@@ -1,7 +1,6 @@
 from __future__ import annotations
 
-from tox.config.loader.ini.factor import extend_factors
-from tox.config.loader.replacer import expand_ranges
+from tox.config.loader.ini.factor import extend_factors, expand_ranges
 from tox.config.loader.section import Section
 
 

From 3c4a8df9cb1b8c16bb43e3755d926fd10e11a693 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Sun, 23 Mar 2025 15:23:47 +0000
Subject: [PATCH 4/6] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 src/tox/config/loader/ini/factor.py  | 4 +++-
 src/tox/config/loader/replacer.py    | 2 +-
 src/tox/config/source/ini_section.py | 2 +-
 3 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/tox/config/loader/ini/factor.py b/src/tox/config/loader/ini/factor.py
index d10dd28d8d..11b4fa66d5 100644
--- a/src/tox/config/loader/ini/factor.py
+++ b/src/tox/config/loader/ini/factor.py
@@ -92,6 +92,7 @@ def name_with_negate(factor: str) -> tuple[str, bool]:
 def is_negated(factor: str) -> bool:
     return factor.startswith("!")
 
+
 def expand_ranges(value: str) -> str:
     """Expand ranges in env expressions, eg py3{10-13} -> "py3{10,11,12,13}"""
     matches = re.findall(r"((\d+)-(\d+)|\d+)(?:,|})", value)
@@ -104,10 +105,11 @@ def expand_ranges(value: str) -> str:
             value = value.replace(src, expansion, 1)
     return value
 
+
 __all__ = (
     "expand_factors",
+    "expand_ranges",
     "extend_factors",
     "filter_for_env",
     "find_envs",
-    "expand_ranges",
 )
diff --git a/src/tox/config/loader/replacer.py b/src/tox/config/loader/replacer.py
index d1ab6a9e38..5d9fd70ebd 100644
--- a/src/tox/config/loader/replacer.py
+++ b/src/tox/config/loader/replacer.py
@@ -4,7 +4,6 @@
 
 import logging
 import os
-import re
 import sys
 from abc import ABC, abstractmethod
 from typing import TYPE_CHECKING, Any, Final, Sequence, Union
@@ -287,6 +286,7 @@ def replace_env(conf: Config | None, args: list[str], conf_args: ConfigLoadArgs)
 def replace_tty(args: list[str]) -> str:
     return (args[0] if len(args) > 0 else "") if sys.stdout.isatty() else args[1] if len(args) > 1 else ""
 
+
 __all__ = [
     "MatchExpression",
     "MatchRecursionError",
diff --git a/src/tox/config/source/ini_section.py b/src/tox/config/source/ini_section.py
index 175444693a..7ed3267f74 100644
--- a/src/tox/config/source/ini_section.py
+++ b/src/tox/config/source/ini_section.py
@@ -1,6 +1,6 @@
 from __future__ import annotations
 
-from tox.config.loader.ini.factor import extend_factors, expand_ranges
+from tox.config.loader.ini.factor import expand_ranges, extend_factors
 from tox.config.loader.section import Section
 
 

From f8dc100ab05a396a15ad33ccbd490f248ca14788 Mon Sep 17 00:00:00 2001
From: Martin Imre <martinimre25@gmail.com>
Date: Thu, 27 Mar 2025 09:15:04 +0100
Subject: [PATCH 5/6] fixup! feat(config): Allow ranges in envlist

---
 docs/changelog/3502.feature.rst | 2 +-
 docs/config.rst                 | 8 +++++++-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/docs/changelog/3502.feature.rst b/docs/changelog/3502.feature.rst
index 85b6373bb3..47772b8de4 100644
--- a/docs/changelog/3502.feature.rst
+++ b/docs/changelog/3502.feature.rst
@@ -1 +1 @@
-Add ranges to generative environments such as py3{10-13}. - by :user:`mimre25`
+Add support for number ranges in generative environments, more details :ref:`here<generative-environment-list>`. - by :user:`mimre25`
diff --git a/docs/config.rst b/docs/config.rst
index eb367a3a25..86e2826880 100644
--- a/docs/config.rst
+++ b/docs/config.rst
@@ -1554,6 +1554,8 @@ Conditional settings
   Here pip will be always installed as the configuration value is not conditional. black is only used for the ``format``
   environment, while ``pytest`` is only installed for the ``py310`` and ``py39`` environments.
 
+.. _generative-environment-list:
+
 Generative environment list
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
@@ -1595,13 +1597,15 @@ This will generate the following tox environments:
     py311-django40-sqlite -> [no description]
     py311-django40-mysql  -> [no description]
 
-Both enumerations (`{1,2,3}`) and ranges (`{1-3}`) are supported, and can be mixed together:
+Both enumerations (``{1,2,3}``) and numerical ranges (``{1-3}``) are supported, and can be mixed together:
+
 .. code-block:: ini
 
     [tox]
     env_list = py3{8-10, 11, 13-14}
 
 will create the following envs:
+
 .. code-block:: shell
 
     > tox l
@@ -1613,6 +1617,8 @@ will create the following envs:
     py313 -> [no description]
     py314 -> [no description]
 
+Negative ranges will also be expanded (``{3-1}`` -> ``{3,2,1}``), however, open ranges such as ``{1-}``, ``{-2}``, ``{a-}``, and ``{-b}`` will not be expanded.
+
 
 
 Generative section names

From 143270feaddac423c8db5a61c9190df7324f4a66 Mon Sep 17 00:00:00 2001
From: Martin Imre <martinimre25@gmail.com>
Date: Thu, 27 Mar 2025 09:15:18 +0100
Subject: [PATCH 6/6] fixup! feat(config): Allow ranges in envlist

---
 tests/config/loader/ini/test_factor.py | 47 +++++++++++++++++---------
 1 file changed, 31 insertions(+), 16 deletions(-)

diff --git a/tests/config/loader/ini/test_factor.py b/tests/config/loader/ini/test_factor.py
index b86c4a129d..5dbc50b576 100644
--- a/tests/config/loader/ini/test_factor.py
+++ b/tests/config/loader/ini/test_factor.py
@@ -181,12 +181,20 @@ def test_factor_config_no_env_list_creates_env(tox_ini_conf: ToxIniCreator) -> N
 @pytest.mark.parametrize(
     ("env_list", "expected_envs"),
     [
-        ("py3{10-13}", ["py310", "py311", "py312", "py313"]),
-        ("py3{10-11},a", ["py310", "py311", "a"]),
-        ("py3{10-11},a{1-2}", ["py310", "py311", "a1", "a2"]),
-        ("py3{10-12,14}", ["py310", "py311", "py312", "py314"]),
-        ("py3{8-10,12,14-16}", ["py38", "py39", "py310", "py312", "py314", "py315", "py316"]),
-        (
+        pytest.param("py3{10-13}", ["py310", "py311", "py312", "py313"], id="Expand positive range"),
+        pytest.param("py3{10-11},a", ["py310", "py311", "a"], id="Expand range and add additional env"),
+        pytest.param("py3{10-11},a{1-2}", ["py310", "py311", "a1", "a2"], id="Expand multiple env with ranges"),
+        pytest.param(
+            "py3{10-12,14}",
+            ["py310", "py311", "py312", "py314"],
+            id="Expand ranges, and allow extra parameter in generator",
+        ),
+        pytest.param(
+            "py3{8-10,12,14-16}",
+            ["py38", "py39", "py310", "py312", "py314", "py315", "py316"],
+            id="Expand multiple ranges for one generator",
+        ),
+        pytest.param(
             "py3{10-11}-django1.{3-5}",
             [
                 "py310-django1.3",
@@ -196,8 +204,9 @@ def test_factor_config_no_env_list_creates_env(tox_ini_conf: ToxIniCreator) -> N
                 "py311-django1.4",
                 "py311-django1.5",
             ],
+            id="Expand ranges and factor multiple environment parts",
         ),
-        (
+        pytest.param(
             "py3{10-11, 13}-django1.{3-4, 6}",
             [
                 "py310-django1.3",
@@ -210,16 +219,22 @@ def test_factor_config_no_env_list_creates_env(tox_ini_conf: ToxIniCreator) -> N
                 "py313-django1.4",
                 "py313-django1.6",
             ],
+            id="Expand ranges and parameters and factor multiple environment parts",
+        ),
+        pytest.param(
+            "py3{10-11},a{1-2}-b{3-4}",
+            ["py310", "py311", "a1-b3", "a1-b4", "a2-b3", "a2-b4"],
+            id="Expand ranges and parameters & factor multiple environment parts for multiple generative environments",
         ),
-        ("py3{10-11},a{1-2}-b{3-4}", ["py310", "py311", "a1-b3", "a1-b4", "a2-b3", "a2-b4"]),
-        ("py3{13-11}", ["py313", "py312", "py311"]),
-        ("py3{-11}", ["py3-11"]),
-        ("foo{11-}", ["foo11-"]),
-        ("foo{a-}", ["fooa-"]),
-        ("foo{-a}", ["foo-a"]),
-        ("foo{a-11}", ["fooa-11"]),
-        ("foo{13-a}", ["foo13-a"]),
-        ("foo{a-b}", ["fooa-b"]),
+        pytest.param("py3{13-11}", ["py313", "py312", "py311"], id="Expand negative ranges"),
+        pytest.param("3.{10-13}", ["3.10", "3.11", "3.12", "3.13"], id="Expand new-style python envs"),
+        pytest.param("py3{-11}", ["py3-11"], id="Don't expand left-open numerical range"),
+        pytest.param("foo{11-}", ["foo11-"], id="Don't expand right-open numerical range"),
+        pytest.param("foo{a-}", ["fooa-"], id="Don't expand right-open range"),
+        pytest.param("foo{-a}", ["foo-a"], id="Don't expand left-open range"),
+        pytest.param("foo{a-11}", ["fooa-11"], id="Don't expand alpha-umerical range"),
+        pytest.param("foo{13-a}", ["foo13-a"], id="Don't expand numerical-alpha range"),
+        pytest.param("foo{a-b}", ["fooa-b"], id="Don't expand non-numerical range"),
     ],
 )
 def test_env_list_expands_ranges(env_list: str, expected_envs: list[str], tox_ini_conf: ToxIniCreator) -> None: