diff --git a/pkgs/sagemath-gap/tox.ini b/pkgs/sagemath-gap/tox.ini
new file mode 100644
index 00000000000..492c30f3252
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+++ b/pkgs/sagemath-gap/tox.ini
@@ -0,0 +1,64 @@
+# To build and test in the tox environment:
+#
+# ./sage -sh -c '(cd pkgs/sagemath-gap && tox -v -v -v -e sagepython)'
+#
+# To test interactively:
+#
+# pkgs/sagemath-gap/.tox/sagepython/bin/python
+#
+[tox]
+envlist =
+    sagepython-norequirements
+
+[testenv]
+deps =
+    !norequirements: -rrequirements.txt
+    # tox 3.x does not handle extras when using --installpkg. https://github.com/tox-dev/tox/issues/1576
+    sagemath-repl
+
+extras = test
+
+passenv =
+    # Variables set by .homebrew-build-env
+                             CPATH
+                             LIBRARY_PATH
+                             PKG_CONFIG_PATH
+    # Parallel build
+                             SAGE_NUM_THREADS
+                             SAGE_NUM_THREADS_PARALLEL
+    # SAGE_VENV only for referring to the basepython or finding the wheels
+    sagepython, sagewheels:  SAGE_VENV
+    # Location of the wheels
+    sagewheels:              SAGE_SPKG_WHEELS
+
+setenv =
+    # Sage scripts such as sage-runtests like to use $HOME/.sage
+                             HOME={envdir}
+    # We supply pip options by environment variables so that they
+    # apply both to the installation of the dependencies and of the package
+    sagewheels:              PIP_FIND_LINKS=file://{env:SAGE_SPKG_WHEELS:{env:SAGE_VENV:{toxinidir}/../../../../venv}/var/lib/sage/wheels}
+    nopypi:                  PIP_NO_INDEX=true
+
+whitelist_externals =
+    bash
+
+commands =
+    # Beware of the treacherous non-src layout. "./sage/" shadows the install sage package.
+    # Importing sage.libs.gap.libgap does not work yet because of the runtime dep on 'sage.rings.polynomial'
+    # {envpython} -c 'import sys; "" in sys.path and sys.path.remove(""); import sage.libs.gap.libgap'
+
+
+[testenv:sagepython]
+basepython = {env:SAGE_VENV}/bin/python3
+
+[testenv:sagepython-sagewheels-nopypi]
+basepython = {env:SAGE_VENV}/bin/python3
+
+[testenv:sagepython-sagewheels-nopypi-norequirements]
+basepython = {env:SAGE_VENV}/bin/python3
+
+[testenv:sagepython-sagewheels]
+basepython = {env:SAGE_VENV}/bin/python3
+
+[testenv:sagepython-norequirements]
+basepython = {env:SAGE_VENV}/bin/python3