Add tox -e benchmarks

docs/sphinx/development.rst

@@ -79,7 +79,7 @@ for some examples.
 Since this takes some time, benchmarks are not run with the default test suite, 
 but has to be enabled like so::
 
-    $ pytest --benchmarks
+    $ tox -e benchmarks
 
 
 Code

tox.ini

@@ -75,8 +75,6 @@ description = Reformat python code using ruff (Black, isort, and pyupgrade)
 skip_install = true
 deps =
     ruff
-allowlist_externals =
-    bash
 changedir = {toxinidir}
 commands =
     ruff check --fix nutree tests setup.py 
@@ -99,3 +97,17 @@ deps =
 commands =
     # http://www.sphinx-doc.org/en/master/man/sphinx-build.html
     sphinx-build -b html sphinx sphinx-build
+
+[testenv:benchmarks]
+description = Run 'pytest --benchmarks' on all Python versions
+; envlist = py38, py39, py310, py311, py312
+skip_install = true
+changedir = {toxinidir}
+basepython = py312
+; basepython = py39
+; basepython = py{38, 39}
+; deps =
+;     pytest
+commands =
+    python -V
+    pytest -k test_bench -o addopts="" --benchmarks