Add CI for Windows

.travis.yml

@@ -41,8 +41,10 @@ x-pyenv-env: &x-pyenv-env >
   PATH="${PYENV_ROOT}/shims:${PATH}"
 
 x-pyenv-install: &x-pyenv-install |
-  # Ensure we have the targeted Python for tox to find on $PATH
-  PYENV="${PYENV_ROOT}/bin/pyenv"
+  # Ensure we have the targeted Python for tox to find on $PATH.
+  # Relative symlinks don't work on Git Bash, which is why
+  # "${PYENV_ROOT}/bin/pyenv" isn't used.
+  PYENV="${PYENV_ROOT}/libexec/pyenv"
   if [ ! -x "${PYENV}" ]; then
     rm -rf ${PYENV_ROOT}
     git clone https://github.com/pyenv/pyenv "${PYENV_ROOT}";
@@ -51,6 +53,9 @@ x-pyenv-install: &x-pyenv-install |
   "${PYENV}" install --keep --skip-existing ${PYENV_VERSION}
   "${PYENV}" global ${PYENV_VERSION}
 
+x-pyenv-27-env: &x-pyenv-27-env >
+  PYENV_VERSION=2.7.18
+
 x-pyenv-39-env: &x-pyenv-39-env >
   PYENV_VERSION=3.9.1
 
@@ -89,7 +94,7 @@ x-osx-27-shard: &x-osx-27-shard
   env:
     - *x-tox-env
     - *x-pyenv-env
-    - PYENV_VERSION=2.7.18
+    - *x-pyenv-27-env
 
 x-osx-39-shard: &x-osx-39-shard
   <<: *x-osx-shard
@@ -98,6 +103,41 @@ x-osx-39-shard: &x-osx-39-shard
     - *x-pyenv-env
     - *x-pyenv-39-env
 
+x-windows-shard: &x-windows-shard
+  os: windows
+  language: shell
+  cache:
+    # The default is 3 minutes (180).
+    timeout: 300
+    directories:
+      - .pyenv_test
+      - "${PYENV_ROOT}"
+  install:
+    - *x-tox-install
+    - *x-pyenv-install
+
+x-windows-27-shard: &x-windows-27-shard
+  <<: *x-windows-shard
+  before_install:
+  - choco install python2
+  - python -m pip install --upgrade pip
+  env:
+    - PATH=/c/Python27:/c/Python27/Scripts:$PATH
+    - *x-tox-env
+    - *x-pyenv-env
+    - *x-pyenv-27-env
+
+x-windows-39-shard: &x-windows-39-shard
+  <<: *x-windows-shard
+  before_install:
+  - choco install python --version 3.9.0
+  - python -m pip install --upgrade pip
+  env:
+    - PATH=/c/Python39:/c/Python39/Scripts:$PATH
+    - *x-tox-env
+    - *x-pyenv-env
+    - *x-pyenv-39-env
+
 # NB: Travis partitions caches using a combination of os, language amd env vars. As such, we do not
 # use TOXENV and instead pass the toxenv via -e on the command line. This helps ensure we share
 # caches as much as possible (eg: all linux python 2.7.15 shards share a cache).
@@ -177,3 +217,19 @@ matrix:
     - <<: *x-osx-39-shard
       name: TOXENV=py39-integration
       script: ${TOX_CMD} -e py39-integration
+
+    - <<: *x-windows-27-shard
+      name: TOXENV=py27
+      script: ${TOX_CMD} -e py27
+
+    - <<: *x-windows-39-shard
+      name: TOXENV=py39
+      script: ${TOX_CMD} -e py39
+
+    - <<: *x-windows-27-shard
+      name: TOXENV=py27-integration
+      script: ${TOX_CMD} -e py27-integration
+
+    - <<: *x-windows-39-shard
+      name: TOXENV=py39-integration
+      script: ${TOX_CMD} -e py39-integration