Update github CI to use poetry

.github/workflows/ci.yaml

@@ -8,22 +8,74 @@ jobs:
     strategy:
       matrix:
         python-version: [3.6, 3.7, 3.8, 3.9, "3.10", "3.11"]
+        # Current (1.7.1) version of poetry doesn't support python < 3.8, and poetry 1.1.13 is the last version with
+        # python 3.6 support, so use it for both python 3.6 and 3.7
+        include:
+          - poetry-version: 1.7.1
+          - python-version: 3.6
+            poetry-version: 1.1.13
+          - python-version: 3.7
+            poetry-version: 1.1.13
       fail-fast: false
+
     steps:
-      - uses: actions/checkout@v2
+      - name: Checkout code
+        uses: actions/checkout@v3
 
       - name: Set up Python ${{ matrix.python-version }}
-        uses: actions/setup-python@v2
+        uses: actions/setup-python@v3
         with:
           python-version: ${{ matrix.python-version }}
 
+      - name: Load cached Poetry installation
+        id: cached-poetry
+        uses: actions/cache@v3
+        with:
+          path: ~/.local  # the path depends on the OS
+          key: poetry-${{ matrix.poetry-version }}-${{ matrix.python-version }}
+
+      - name: Install Poetry
+        if: steps.cached-poetry.outputs.cache-hit != 'true'
+        uses: snok/install-poetry@v1
+        with:
+          version: ${{ matrix.poetry-version }}
+          virtualenvs-create: true
+          virtualenvs-in-project: true
+          installer-parallel: true
+
+      - name: Unset unsupported group directive from pyproject.toml for poetry 1.1.13
+        if: matrix.poetry-version == '1.1.13'
+        # removing the section and one string after it, that contains sphinx dependency, that isn't needed for these
+        # tests anyway
+        run: sed -i '/\[tool.poetry.group.docs.dependencies\]/,+1 d' pyproject.toml
+
+      # Checking pyproject.toml just in case
+      - name: Check pyproject.toml validity
+        run: poetry check --no-interaction
+
+      # The lock file format has changed since 1.1.3, so we just recreate it.
+      # Be aware that it will have different versions, than the repository lock file.
+      - name: Recreate lock file (for poetry 1.1.13)
+        if: matrix.poetry-version == '1.1.13'
+        # poetry.lock should be deleted before recreating it, or an error occurs
+        run: rm poetry.lock && poetry lock
+
+      - name: Load cached venv
+        id: cached-poetry-dependencies
+        uses: actions/cache@v3
+        with:
+          path: .venv
+          key: venv-${{ runner.os }}-${{ steps.setup-python.outputs.python-version }}-${{ hashFiles('**/poetry.lock') }}
+
       - name: Install dependencies
-        run: |
-          sudo apt update
-          sudo apt-get install -y libxml2-dev libxmlsec1-dev
-          python -m pip install --upgrade pip
-          pip install -r requirements.txt
+        if: steps.cached-poetry-dependencies.outputs.cache-hit != 'true'
+        # --no-root because it makes no sense to install our package into cache.
+        run: poetry install --no-interaction --no-root
+
+      # If we would need our package installed - here is the way. But we don't.
+      # - name: Install project
+      #   run: poetry install --no-interaction
 
       - name: Run tests
         run: |
-          python -m unittest tests.tests
+          poetry run python -m unittest tests.tests