Add installation of missing python versions.

appveyor.yml

@@ -30,57 +30,107 @@ environment:
     - PYTHON_ROOT: "C:\\Python27"
       PYTHON_ARCH: "32"
       PYTHON_VERSION: "2.7.x"
+      PYTHON_EXE: python
 
     - PYTHON_ROOT: "C:\\Python27-x64"
       PYTHON_ARCH: "64"
       PYTHON_VERSION: "2.7.x"
+      PYTHON_EXE: python
 
     - PYTHON_ROOT: "C:\\Python35"
       PYTHON_ARCH: "32"
       PYTHON_VERSION: "3.5.x"
+      PYTHON_EXE: python
 
     - PYTHON_ROOT: "C:\\Python35-x64"
       PYTHON_ARCH: "64"
       PYTHON_VERSION: "3.5.x"
+      PYTHON_EXE: python
 
     - PYTHON_ROOT: "C:\\Python36"
       PYTHON_ARCH: "32"
       PYTHON_VERSION: "3.6.x"
+      PYTHON_EXE: python
 
     - PYTHON_ROOT: "C:\\Python36-x64"
       PYTHON_ARCH: "64"
       PYTHON_VERSION: "3.6.x"
+      PYTHON_EXE: python
 
     - PYTHON_ROOT: "C:\\Python37"
       PYTHON_ARCH: "32"
       PYTHON_VERSION: "3.7.x"
+      PYTHON_EXE: python
 
     - PYTHON_ROOT: "C:\\Python37-x64"
       PYTHON_ARCH: "64"
       PYTHON_VERSION: "3.7.x"
+      PYTHON_EXE: python
 
     - PYTHON_ROOT: "C:\\Python38"
       PYTHON_ARCH: "32"
       PYTHON_VERSION: "3.8.x"
+      PYTHON_EXE: python
 
     - PYTHON_ROOT: "C:\\Python38-x64"
       PYTHON_ARCH: "64"
       PYTHON_VERSION: "3.8.x"
+      PYTHON_EXE: python
 
     - PYTHON_ROOT: "C:\\Python39"
       PYTHON_ARCH: "32"
       PYTHON_VERSION: "3.9.x"
+      PYTHON_EXE: python
 
     - PYTHON_ROOT: "C:\\Python39-x64"
       PYTHON_ARCH: "64"
       PYTHON_VERSION: "3.9.x"
+      PYTHON_EXE: python
 
 cache:
   - "%TMP%\\py\\"
   - '%LOCALAPPDATA%\pip\Cache -> appveyor.yml,setup.py'
 
 install:
-  - "SET PATH=%PYTHON_ROOT%;%PYTHON_ROOT%\\Scripts;%PATH%"
+  # If there is a newer build queued for the same PR, cancel this one.
+  # The AppVeyor 'rollout builds' option is supposed to serve the same
+  # purpose but it is problematic because it tends to cancel builds pushed
+  # directly to master instead of just PR builds (or the converse).
+  # credits: JuliaLang developers.
+  - ps: if ($env:APPVEYOR_PULL_REQUEST_NUMBER -and $env:APPVEYOR_BUILD_NUMBER -ne ((Invoke-RestMethod `
+        https://ci.appveyor.com/api/projects/$env:APPVEYOR_ACCOUNT_NAME/$env:APPVEYOR_PROJECT_SLUG/history?recordsNumber=50).builds | `
+        Where-Object pullRequestId -eq $env:APPVEYOR_PULL_REQUEST_NUMBER)[0].buildNumber) { `
+          throw "There are newer queued builds for this pull request, failing early." }
+  - ECHO "Filesystem root:"
+  - ps: "ls \"C:/\""
+
+  - ECHO "Installed SDKs:"
+  - ps: "if(Test-Path(\"C:/Program Files/Microsoft SDKs/Windows\")) {ls \"C:/Program Files/Microsoft SDKs/Windows\";}"
+
+  # Install Python (from the official .msi of http://python.org) and pip when
+  # not already installed.
+  # PyPy portion based on https://github.com/wbond/asn1crypto/blob/master/appveyor.yml
+  - ps:
+      $env:PYTMP = "${env:TMP}\py";
+      if (!(Test-Path "$env:PYTMP")) {
+        New-Item -ItemType directory -Path "$env:PYTMP" | Out-Null;
+      }
+      if ("${env:PYTHON_ID}" -eq "pypy") {
+        if (!(Test-Path "${env:PYTMP}\pypy2-v7.3.1-win32.zip")) {
+          (New-Object Net.WebClient).DownloadFile('https://bitbucket.org/pypy/pypy/downloads/pypy2.7-v7.3.1-win32.zip', "${env:PYTMP}\pypy2-v7.3.1-win32.zip");
+        }
+        7z x -y "${env:PYTMP}\pypy2-v7.3.1-win32.zip" -oC:\ | Out-Null;
+      }
+      elseif (-not(Test-Path($env:PYTHON))) {
+        & appveyor\install.ps1;
+      }
+
+  # Prepend newly installed Python to the PATH of this build (this cannot be
+  # done from inside the powershell script as it would require to restart
+  # the parent CMD process).
+  - "SET PATH=%PYTHON%;%PYTHON%\\Scripts;%PYTHON%\\bin;%PATH%"
+  - "SET PYEXE=%PYTHON%\\%PYTHON_EXE%.exe"
+
   - "python --version"
   - "python -c \"import struct; print(struct.calcsize('P') * 8)\""