Test against pip==23.1 (#180)

Author: di

tests/test_installed_distributions.py

@@ -59,6 +59,7 @@ def test_installed_distributions_editable(pip, some_editable_distribution):
         assert distribution.editable
 
 
+@pytest.mark.xfail(pip_api.PIP_VERSION >= parse("23.1"), reason="Unsupported")
 def test_installed_distributions_legacy_version(pip, data):
     # Use an older setuptools to build this with a legacy version
     pip.run("install", "setuptools<66")

tox.ini

@@ -1,10 +1,10 @@
 [tox]
 envlist=
-    py37-pip{2301,230,2231,223,2222,2221,222,2212,2211,221,2204,2203,2202,2201,220,2131,213,2124,2123,2122,2121,212,2113,2112,2111,211,2101,210,2034,2033,2031,203,2024,2023,2022,2021,202,201,2002,2001,1931,193,1923,1922,1921,192,1911,191,1903,1902,1901,190,181},
-    py38-pip{2301,230,2231,223,2222,2221,222,2212,2211,221,2204,2203,2202,2201,220,2131,213,2124,2123,2122,2121,212,2113,2112,2111,211,2101,210,2034,2033,2031,203,2024,2023,2022,2021,202,201,2002,2001,1931},
-    py39-pip{2301,230,2231,223,2222,2221,222,2212,2211,221,2204,2203,2202,2201,220,2131,213,2124,2123,2122,2121,212,2113,2112,2111,211,2101,210,2034,2033,2031,203},
-    py310-pip{2301,230,2231,223,2222,2221,222,2212,2211,221,2204,2203,2202,2201,220,2131,213},
-    py311-pip{2301,230,2231,223,2222,2221,222},
+    py37-pip{231,2301,230,2231,223,2222,2221,222,2212,2211,221,2204,2203,2202,2201,220,2131,213,2124,2123,2122,2121,212,2113,2112,2111,211,2101,210,2034,2033,2031,203,2024,2023,2022,2021,202,201,2002,2001,1931,193,1923,1922,1921,192,1911,191,1903,1902,1901,190,181},
+    py38-pip{231,2301,230,2231,223,2222,2221,222,2212,2211,221,2204,2203,2202,2201,220,2131,213,2124,2123,2122,2121,212,2113,2112,2111,211,2101,210,2034,2033,2031,203,2024,2023,2022,2021,202,201,2002,2001,1931},
+    py39-pip{231,2301,230,2231,223,2222,2221,222,2212,2211,221,2204,2203,2202,2201,220,2131,213,2124,2123,2122,2121,212,2113,2112,2111,211,2101,210,2034,2033,2031,203},
+    py310-pip{231,2301,230,2231,223,2222,2221,222,2212,2211,221,2204,2203,2202,2201,220,2131,213},
+    py311-pip{231,2301,230,2231,223,2222,2221,222},
     lint
 
 [testenv]
@@ -13,6 +13,7 @@ deps=
     pretend
     pytest
     virtualenv>20
+    pip231: pip==23.1
     pip2301: pip==23.0.1
     pip230: pip==23.0
     pip2231: pip==22.3.1