TestKit Docker: install tools for all python versions

Author: robsdedude

testkit/Dockerfile

@@ -39,18 +39,19 @@ RUN git clone https://github.com/pyenv/pyenv.git .pyenv
 ENV PYENV_ROOT /.pyenv
 ENV PATH $PYENV_ROOT/shims:$PYENV_ROOT/bin:$PATH
 
-# Set minimum supported Python version
-RUN pyenv install 3.6:latest
-RUN pyenv install 3.7:latest
-RUN pyenv install 3.8:latest
-RUN pyenv install 3.9:latest
+# Setup python version
+ENV PYTHON_VERSIONS 3.6 3.7 3.8 3.9
+
+RUN for version in $PYTHON_VERSIONS; do \
+        pyenv install $version:latest; \
+    done
 RUN pyenv rehash
 RUN pyenv global $(pyenv versions --bare --skip-aliases)
 
 # Install Latest pip and setuptools for each environment
 # https://pip.pypa.io/en/stable/news/
-RUN python -m pip install --upgrade pip
-RUN python -m pip install --upgrade setuptools
-
-# Install Python Testing Tools
-RUN python -m pip install coverage tox
+RUN for version in $PYTHON_VERSIONS; do \
+        python$version -m pip install -U pip && \
+        python$version -m pip install -U setuptools && \
+        python$version -m pip install -U coverage tox tox-factor; \
+    done