Add pytest CI job

.github/workflows/ci_tests.yml

@@ -105,3 +105,39 @@ jobs:
 
             exit 1
           }
+
+  pytest:
+    runs-on: ubuntu-latest
+
+    strategy:
+      fail-fast: false
+      matrix:
+        python_version: ["3.10", "3.11", "3.12"]
+
+    steps:
+      - name: Checkout ${{ github.repository }}
+        uses: actions/checkout@v4
+
+      - name: Setup Python ${{ matrix.python_version }}
+        uses: actions/setup-python@v4
+        with:
+          python-version: ${{ matrix.python_version }}
+
+      - name: Install test dependencies
+        run: |
+          python -m pip install -U pip
+          pip install -U setuptools wheel flit
+          pip install -U -e .[testing]
+
+      - name: Run pytest
+        run: pytest -vv --cov-report=xml
+
+      - name: Upload coverage
+        if: github.repository_owner == 'SINTEF' && matrix.python_version == '3.10'
+        uses: codecov/codecov-action@v3
+        with:
+          fail_ci_if_error: true
+          env_vars: OS,PYTHON
+        env:
+          OS: ubuntu-latest
+          PYTHON: ${{ matrix.python_version }}