.gitlab-ci.yml: use matrix for python versions, add docs #3

Also, Python 3.11 was added to testing, and .test-python3 was removed as we only do Python3 anyway.

Author: greenrobot

.gitlab-ci.yml

@@ -27,43 +27,29 @@ build:
     paths:
       - dist/*.whl
 
-# Next, test the packaged wheel
+# Next, test the packaged wheel built by "build"
 .test:
   stage: test
   script:
-    - pip3 install --user pytest
-    - pip3 install --user numpy
-    - rm -r objectbox
-    - pip3 install --user --force-reinstall dist/*.whl
+    - pip3 install --user pytest numpy
+    - rm -r objectbox  # todo this is ugly; let's copy required files in a sub-folder instead?
+    - pip3 install --user --force-reinstall dist/*.whl  # Artifacts from the previous stage (downloaded by default)
     - ${PYTHON} -m pytest
-
-.test-python3:
-  extends: .test
   variables:
     PYTHON: "python3"
 
-.test:linux:x64:
-  extends: .test-python3
+test:linux:x64:
+  extends: .test
   tags: [x64, docker, linux]
-
-test:linux:x64:3.7:
-  extends: .test:linux:x64
-  image: python:3.7
-
-test:linux:x64:3.8:
-  extends: .test:linux:x64
-  image: python:3.8
-
-test:linux:x64:3.9:
-  extends: .test:linux:x64
-  image: python:3.9
-
-test:linux:x64:3.10:
-  extends: .test:linux:x64
-  image: python:3.10
+  image: python:$PYTHON_VERSION
+  parallel:
+    matrix:
+      # Note: Docker images will have an arbitrary minor version due to "if-not-present" pull policy.
+      #       If this becomes a problem, we could e.g. specify a minor version explicitly.
+      - PYTHON_VERSION: [ '3.7', '3.8', '3.9', '3.10', '3.11']
 
 # test:linux:armv7hf:
-#   extends: .test-python3
+#   extends: .test
 #   tags: [armv7hf, shell, linux, python3]
 
 # aarch64 version not published
@@ -72,7 +58,7 @@ test:linux:x64:3.10:
 #  tags: [aarch64, shell, linux, python3]
 
 test:mac:x64:
-  extends: .test-python3
+  extends: .test
   tags: [mac, x64, shell, python3]
 
 test:windows:x64: