Test through docker image (CircleCI)

.circleci/config.yml

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+
+version: 2.1
+
+jobs:
+  build:
+    docker:
+      - image: themattrix/tox-base@sha256:90652d28db65c8977b985ecfaaeed72de2092c930eec123cca31e17ac20a2622
+
+    environment:
+      # prevent *.pyc files
+      PYTHONDONTWRITEBYTECODE: 1
+
+    steps:
+      - checkout
+      - run:
+          name: Install git and mercurial
+          command: |
+            apt-get update
+            apt-get install -y git-core
+            apt-get install -y mercurial
+            git config --global user.email "bumpversion_test@example.org"
+            git config --global user.name "Bumpversion Test"
+      - run:
+          name: Update pyenv
+          # to access newer Python releases.
+          command: |
+            cd /.pyenv
+            git fetch
+            git checkout v1.2.15
+      - run:
+          name: Install python interpreters
+          command: |
+            pyenv versions
+            # for the list of pre-installed Python versions in the docker image,
+            # see https://github.com/themattrix/docker-tox-base/blob/master/python-versions.txt
+            pyenv global system 2.7.17 3.5.7 3.6.9 3.7.5 pypy2.7-7.2.0 pypy3.6-7.2.0
+
+      - run:
+          name: Run tests
+          command: tox