ci: fan out Azure pipelines on Python version (parallel matrix)

Previously, each (os, test_suite) pair ran as a single Azure Pipelines
job and iterated over python_versions as a template loop inside that
job's steps:

    strategy:
        matrix:
            <test_suite>: {...}
    steps:
        - ${{ each pyver in parameters.python_versions }}:
            - install python pyver
            - configure
            - run test_suite

Consequence: all Python versions for a given (os, test_suite) ran
sequentially on the same agent. If the first Python version failed
(e.g. an env-specific test failure on the *_latest_from_pip matrix),
all subsequent Python versions were skipped instead of also running
and showing whether they were affected.

Move python_version into the strategy.matrix so each
(python_version, test_suite) combination runs as its own parallel
job on its own agent VM. Each job becomes shorter (one Python
install + configure + test run instead of N of each) and an issue
affecting one Python version no longer hides results for the others.

Matrix keys are of the form 'py3_10_all' / 'py3_11_misc_and_scancode'
etc. (matrix keys must be alphanumeric+underscore, so dots in version
strings are replaced).

No changes to the per-job test command or to the caller pipelines in
azure-pipelines.yml -- the python_versions and test_suites parameters
keep the same shape.

Signed-off-by: Guillem Serra Cazorla <gserracazorla@gmail.com>

Author: GuillemSeCa

etc/ci/azure-posix.yml

@@ -11,29 +11,35 @@ jobs:
       pool:
           vmImage: ${{ parameters.image_name }}
 
+      # Fan out on both Python version AND test suite so each
+      # (python_version, test_suite) combination runs as its own parallel
+      # job on its own agent VM. Previously python_versions were iterated
+      # as sequential steps inside a single job, so a failure on the first
+      # Python version skipped all subsequent ones.
       strategy:
           matrix:
-              ${{ each tsuite in parameters.test_suites }}:
-                 ${{ tsuite.key }}:
-                     test_suite_label: ${{ tsuite.key }}
-                     test_suite: ${{ tsuite.value }}
+              ${{ each pyver in parameters.python_versions }}:
+                  ${{ each tsuite in parameters.test_suites }}:
+                      py${{ replace(pyver, '.', '_') }}_${{ tsuite.key }}:
+                          python_version: ${{ pyver }}
+                          test_suite_label: ${{ tsuite.key }}
+                          test_suite: ${{ tsuite.value }}
 
       steps:
           - checkout: self
             fetchDepth: 10
 
-          - ${{ each pyver in parameters.python_versions }}:
-              - task: UsePythonVersion@0
-                inputs:
-                    versionSpec: '${{ pyver }}'
-                    architecture: '${{ parameters.python_architecture }}'
-                displayName: '${{ pyver }} - Install Python'
+          - task: UsePythonVersion@0
+            inputs:
+                versionSpec: '$(python_version)'
+                architecture: '${{ parameters.python_architecture }}'
+            displayName: 'Install Python $(python_version)'
 
-              - script: |
-                    python${{ pyver }} --version
-                    echo "python${{ pyver }}" > PYTHON_EXECUTABLE
-                    ./configure --clean && ./configure --dev
-                displayName: '${{ pyver }} - Configure'
+          - script: |
+                python$(python_version) --version
+                echo "python$(python_version)" > PYTHON_EXECUTABLE
+                ./configure --clean && ./configure --dev
+            displayName: 'Configure with Python $(python_version)'
 
-              - script: $(test_suite)
-                displayName: '${{ pyver }} - $(test_suite_label) on ${{ parameters.job_name }}'
+          - script: $(test_suite)
+            displayName: '$(test_suite_label) on ${{ parameters.job_name }} with Python $(python_version)'

etc/ci/azure-win.yml

@@ -11,29 +11,35 @@ jobs:
       pool:
           vmImage: ${{ parameters.image_name }}
 
+      # Fan out on both Python version AND test suite so each
+      # (python_version, test_suite) combination runs as its own parallel
+      # job on its own agent VM. Previously python_versions were iterated
+      # as sequential steps inside a single job, so a failure on the first
+      # Python version skipped all subsequent ones.
       strategy:
           matrix:
-              ${{ each tsuite in parameters.test_suites }}:
-                 ${{ tsuite.key }}:
-                     test_suite_label: ${{ tsuite.key }}
-                     test_suite: ${{ tsuite.value }}
+              ${{ each pyver in parameters.python_versions }}:
+                  ${{ each tsuite in parameters.test_suites }}:
+                      py${{ replace(pyver, '.', '_') }}_${{ tsuite.key }}:
+                          python_version: ${{ pyver }}
+                          test_suite_label: ${{ tsuite.key }}
+                          test_suite: ${{ tsuite.value }}
 
       steps:
           - checkout: self
             fetchDepth: 10
 
-          - ${{ each pyver in parameters.python_versions }}:
-              - task: UsePythonVersion@0
-                inputs:
-                    versionSpec: '${{ pyver }}'
-                    architecture: '${{ parameters.python_architecture }}'
-                displayName: '${{ pyver }} - Install Python'
+          - task: UsePythonVersion@0
+            inputs:
+                versionSpec: '$(python_version)'
+                architecture: '${{ parameters.python_architecture }}'
+            displayName: 'Install Python $(python_version)'
 
-              - script: |
-                   python --version
-                   echo | set /p=python> PYTHON_EXECUTABLE
-                   configure --clean && configure --dev
-                displayName: '${{ pyver }} - Configure'
+          - script: |
+               python --version
+               echo | set /p=python> PYTHON_EXECUTABLE
+               configure --clean && configure --dev
+            displayName: 'Configure with Python $(python_version)'
 
-              - script: $(test_suite)
-                displayName: '${{ pyver }} - $(test_suite_label) on ${{ parameters.job_name }}'
+          - script: $(test_suite)
+            displayName: '$(test_suite_label) on ${{ parameters.job_name }} with Python $(python_version)'