Update test workflow to include Python 3.9.1 job and fix cache key for

better dependency isolation

Author: Евгений Блинов

.github/workflows/tests_and_coverage.yml

@@ -8,36 +8,36 @@ jobs:
     strategy:
       matrix:
         os: [macos-latest, ubuntu-latest, windows-latest]
-        python-version: ["3.8", "3.9", "3.9.1", "3.10", "3.11", "3.12", "3.13", "3.14", "3.14t", "3.15.0-alpha.1"]
+        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12", "3.13", "3.14", "3.14t", "3.15.0-alpha.1"]
 
     steps:
       - uses: actions/checkout@v4
+
       - name: Set up Python ${{ matrix.python-version }}
         uses: actions/setup-python@v5
         with:
           python-version: ${{ matrix.python-version }}
 
-      - name: Install the library
-        shell: bash
-        run: pip install .
-
       - name: Cache pip dependencies
         uses: actions/cache@v4
         with:
           path: ~/.cache/pip
-          key: ${{ runner.os }}-pip-${{ github.workflow }}-${{ hashFiles('requirements_dev.txt') }}
-          restore-keys: |
-            ${{ runner.os }}-pip-${{ github.workflow }}-
+          key: ${{ runner.os }}-pip-${{ matrix.python-version }}-${{ github.workflow }}-${{ hashFiles('requirements_dev.txt') }}
 
       - name: Install dependencies
         shell: bash
         run: pip install -r requirements_dev.txt
 
+      - name: Install the library
+        shell: bash
+        run: pip install .
+
       - name: Print all libs
         shell: bash
         run: pip list
 
       - name: Run tests and show coverage on the command line
+        shell: bash
         run: |
           coverage run --source=transfunctions --omit="*tests*" -m pytest --cache-clear --assert=plain && coverage report -m --fail-under=94
           coverage xml
@@ -53,4 +53,38 @@ jobs:
         continue-on-error: true
 
       - name: Run tests and show the branch coverage on the command line
+        shell: bash
+        run: coverage run --branch --source=transfunctions --omit="*tests*" -m pytest --cache-clear --assert=plain && coverage report -m --fail-under=94
+
+  # 2. A separate job specifically for bug testing in Python 3.9.1 (Linux only)
+  build-3-9-1:
+    runs-on: ubuntu-latest
+    container: python:3.9.1
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Cache pip dependencies
+        uses: actions/cache@v4
+        with:
+          path: ~/.cache/pip
+          key: ubuntu-pip-3.9.1-${{ github.workflow }}-${{ hashFiles('requirements_dev.txt') }}
+
+      - name: Install dependencies
+        shell: bash
+        run: pip install -r requirements_dev.txt
+
+      - name: Install the library
+        shell: bash
+        run: pip install .
+
+      - name: Print all libs
+        shell: bash
+        run: pip list
+
+      - name: Run tests and show coverage on the command line
+        shell: bash
+        run: coverage run --source=transfunctions --omit="*tests*" -m pytest --cache-clear --assert=plain && coverage report -m --fail-under=94
+
+      - name: Run tests and show the branch coverage on the command line
+        shell: bash
         run: coverage run --branch --source=transfunctions --omit="*tests*" -m pytest --cache-clear --assert=plain && coverage report -m --fail-under=94