[#757] Add more testing for Windows across multiple Python versions

.travis.yml

@@ -8,15 +8,24 @@ git:
 
 before_install:
   - date
-  - pip install poetry~=0.12.17
 
 install:
+  - pip install poetry~=0.12.17
   - poetry install
   - poetry run python --version
 
 script:
   - poetry run behave
 
+aliases:
+  test_windows: &test_windows
+    os: windows
+    language: shell
+    before_install:
+      - choco install python --version $JRNL_PYTHON_VERSION
+      - python -m pip install --upgrade pip
+      - pip --version
+
 jobs:
   allow_failures:
     - python: 3.8
@@ -41,18 +50,21 @@ jobs:
       os: osx
       osx_image: xcode11.2  # Python 3.7.4 running on macOS 10.14.4
       language: shell       # 'language: python' is an error on Travis CI macOS
-      before_install:
-        - pip3 install poetry~=0.12.17  # 'pip' points to Python 2 on MacOS
-    - name: Python 3.7 on Windows
-      os: windows
-      language: shell       # 'language: python' is an error on Travis CI Windows
-      before_install:
-        - choco install python --version 3.7.5
-        - python -m pip install --upgrade pip
-        - pip --version
-        - pip install poetry~=0.12.17
+    - <<: *test_windows
+      name: Python 3.6 on Windows
       env:
+        - JRNL_PYTHON_VERSION=3.6.8
+        - PATH=/c/Python36:/c/Python36/Scripts:$PATH
+    - <<: *test_windows
+      name: Python 3.7 on Windows
+      env:
+        - JRNL_PYTHON_VERSION=3.7.5
         - PATH=/c/Python37:/c/Python37/Scripts:$PATH
+    - <<: *test_windows
+      name: Python 3.8 on Windows
+      env:
+        - JRNL_PYTHON_VERSION=3.8.0
+        - PATH=/c/Python38:/c/Python38/Scripts:$PATH
 
     - stage: Deploy
       if: branch = master AND tag IS present