to add tox

Author: zhenwei-li

README.md

@@ -1,6 +1,6 @@
 # Python-DeMo
 
-Python DeMo
+![Python Logo](https://www.python.org/static/community_logos/python-logo.png "Python DeMo")
 
 - [一. 构建`venv`环境](#一-构建venv环境)
   - [1.1 venv2](#11-venv2)

tox.ini

@@ -0,0 +1,35 @@
+# tox (https://tox.readthedocs.io/) is a tool for running tests
+# in multiple virtualenvs. This configuration file will run the
+# test suite on all supported python versions. To use it, "pip install tox"
+# and then run "tox" from this directory.
+# For information see https://tox.readthedocs.io/en/latest/examples.html
+
+[tox]
+envlist = py27, py39
+
+minversion = 3.23.1
+
+# Activate isolated build environment. tox will use a virtual environment
+# to build a source distribution from the source tree. For build tools and
+# arguments use the pyproject.toml file as specified in PEP-517 and PEP-518.
+isolated_build = true
+
+# install testing framework
+# ... or install anything else you might need here
+[testenv]
+platform = linux: linux
+           macos: darwin
+           windows: win32
+; alwayscopy = True
+allowlist_externals =
+    /bin/bash
+changedir =
+    tests
+deps =
+    build
+    discover
+commands =
+    ; windows: python --version
+    ; macos,linux: python --version
+    discover
+    ; python -m unittest discover