Removing Python 2 configurations for CI runs

.circleci/config.yml

@@ -1,11 +1,11 @@
 version: 2
 
 jobs:
-  osx-python2:
+  osx-python3.6:
     macos:
-      xcode: "10.0.0"
+      xcode: "9.4.1"
     environment:
-      PYTHON: python2
+      PYTHON: python3
     steps:
       - checkout
 
@@ -16,7 +16,7 @@ jobs:
           name: Test.
           command: venv/bin/python ./bin/run_tests.py
 
-  osx-python3:
+  osx-python3.7:
     macos:
       xcode: "10.0.0"
     environment:
@@ -31,23 +31,7 @@ jobs:
           name: Test.
           command: venv/bin/python ./bin/run_tests.py
 
-  linux-python2:
-    docker:
-      - image: circleci/python:2.7
-    environment:
-      PYTHON: python2
-    steps:
-      - checkout
-      - setup_remote_docker
-
-      - run:
-          name: Prepare the environment.
-          command: bash .circleci/prepare.sh
-      - run:
-          name: Test.
-          command: venv/bin/python ./bin/run_tests.py
-
-  linux-python3:
+  linux-python3.6:
     docker:
       - image: circleci/python:3.6
     environment:
@@ -67,7 +51,6 @@ workflows:
   version: 2
   all-tests:
     jobs:
-      - osx-python2
-      - osx-python3
-      - linux-python2
-      - linux-python3
+      - osx-python3.6
+      - osx-python3.7
+      - linux-python3.6

.travis.yml

@@ -2,13 +2,6 @@ language: generic
 
 matrix:
   include:
-    # Linux Python 2
-    - sudo: required
-      language: python
-      python: 2.7
-      services: docker
-      env: PYTHON=python
-
     # Linux Python 3
     - sudo: required
       language: python

CI.md

@@ -0,0 +1,9 @@
+This is a summary of the Python versions and platforms covered by the different CI platforms:
+
+|          | 3.5              | 3.6              | 3.7                   | 3.8              |
+|----------|------------------|------------------|-----------------------|------------------|
+| Linux    | Travis CI        | CircleCI         | AppVeyor              | Azure Pipelines  |
+| macOS    | Azure Pipelines  | CircleCI         | Travis CI¹ / CircleCI | Azure Pipelines  |
+| Windows  | TravisCI         | Azure Pipelines  | AppVeyor              | Azure Pipelines  |
+
+> ¹ Python version not really pinned, but dependent on the (default) version of image used.

appveyor.yml

@@ -3,9 +3,9 @@ image:
   - Visual Studio 2015
 
 build_script:
-  - cmd: "C:\\Python27\\python.exe -m pip install -r requirements-dev.txt"
+  - cmd: "C:\\Python37\\python.exe -m pip install -r requirements-dev.txt"
   - sh: "${HOME}/.localpython3.7.4/bin/python3 -m pip install -r requirements-dev.txt"
   # the '-u' flag is required so the output is in the correct order.
   # See https://github.com/joerick/cibuildwheel/pull/24 for more info.
-  - cmd: "C:\\Python27\\python.exe -u ./bin/run_tests.py"
+  - cmd: "C:\\Python37\\python.exe -u ./bin/run_tests.py"
   - sh: "${HOME}/.localpython3.7.4/bin/python3 ./bin/run_tests.py"

azure-pipelines.yml

@@ -1,5 +1,5 @@
 jobs:
-- job: linux
+- job: linux_38
   pool: {vmImage: 'Ubuntu-18.04'}
   steps:
     - task: UsePythonVersion@0
@@ -9,7 +9,17 @@ jobs:
         python -m pip install -r requirements-dev.txt
         python ./bin/run_tests.py
 
-- job: macos
+- job: macos_35
+  pool: {vmImage: 'macOS-10.13'}
+  steps:
+    - task: UsePythonVersion@0
+      inputs:
+        versionSpec: '3.5'
+    - bash: |
+        python -m pip install -r requirements-dev.txt
+        python ./bin/run_tests.py
+
+- job: macos_38
   pool: {vmImage: 'macOS-10.13'}
   steps:
     - task: UsePythonVersion@0
@@ -19,7 +29,19 @@ jobs:
         python -m pip install -r requirements-dev.txt
         python ./bin/run_tests.py
 
-- job: windows
+- job: windows_36
+  pool: {vmImage: 'vs2017-win2016'}
+  steps:
+    - task: UsePythonVersion@0
+      inputs:
+        versionSpec: '3.6'
+    - script: choco install vcpython27 -f -y
+      displayName: Install Visual C++ for Python 2.7
+    - bash: |
+        python -m pip install -r requirements-dev.txt
+        python ./bin/run_tests.py
+
+- job: windows_38
   pool: {vmImage: 'vs2017-win2016'}
   steps:
     - task: UsePythonVersion@0