refactor: separate build, test, and deploy in Python workflow (#2308)

_Test what you build, deploy what you test._

This refactors the Python CI workflow to wait for _all_ tests to pass
before publishing photonlibpy to PyPI.

- build-python-examples reuses the built wheel, removes redundant builds
- Simplify run.sh to not rebuild wheel since it's already installed

.github/workflows/python.yml

@@ -12,7 +12,7 @@ concurrency:
   cancel-in-progress: true
 
 jobs:
-  build-and-deploy:
+  build-py:
     runs-on: ubuntu-24.04
 
     steps:
@@ -29,38 +29,57 @@ jobs:
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
-          pip install setuptools wheel pytest mypy
+          pip install setuptools wheel
 
       - name: Build wheel
         working-directory: ./photon-lib/py
         run: python setup.py sdist bdist_wheel
 
-      - name: Run Unit Tests
-        working-directory: ./photon-lib/py
-        run: |
-            pip install --no-cache-dir dist/*.whl
-            pytest
-
-      - name: Run mypy type checking
-        run: mypy --show-column-numbers --config-file photon-lib/py/pyproject.toml photon-lib
-
       - name: Upload artifacts
         uses: actions/upload-artifact@v6
         with:
           name: dist
           path: ./photon-lib/py/dist/
 
-      - name: Publish package distributions to TestPyPI
-        # Only upload on tags
-        if: startsWith(github.ref, 'refs/tags/v')
-        uses: pypa/gh-action-pypi-publish@release/v1
-        with:
-          packages-dir: ./photon-lib/py/dist/
+  test-py:
+    needs: build-py
+    runs-on: ubuntu-24.04
 
-    permissions:
-      id-token: write  # IMPORTANT: this permission is mandatory for trusted publishing
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v6
+        with:
+          fetch-depth: 0
+
+      - name: Set up Python
+        uses: actions/setup-python@v6
+        with:
+          python-version: 3.14
+
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install pytest mypy
+
+      - name: Download artifacts
+        uses: actions/download-artifact@v6
+        with:
+          name: dist
+          path: dist/
+
+      - name: Install package
+        shell: bash
+        run: pip install --no-cache-dir dist/*.whl
+
+      - name: Run Unit Tests
+        shell: bash
+        run: pytest --import-mode=importlib photon-lib/py/test/
+
+      - name: Run mypy type checking
+        run: mypy --show-column-numbers --config-file photon-lib/py/pyproject.toml photon-lib
 
   build-python-examples:
+    needs: build-py
     strategy:
       matrix:
         os: [ubuntu-24.04, windows-2022, macos-14]
@@ -81,28 +100,18 @@ jobs:
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
-          pip install setuptools wheel pytest mypy
 
-      - name: Build wheel
-        working-directory: ./photon-lib/py
-        run: python setup.py sdist bdist_wheel
+      - name: Download artifacts
+        uses: actions/download-artifact@v6
+        with:
+          name: dist
+          path: ./photon-lib/py/dist/
 
-      - name: Build and configure PhotonLibPy
-        working-directory: ./photon-lib/py
-        shell: bash
-        run: |
-          ./buildAndTest.sh
-          ./enableUsingDevBuilds.sh
-
-      - name: Run Unit Tests
+      - name: Install PhotonLibPy package
         working-directory: ./photon-lib/py
         shell: bash
         run: |
             pip install --no-cache-dir dist/*.whl
-            pytest
-
-      - name: Run mypy type checking
-        run: mypy --show-column-numbers --config-file photon-lib/py/pyproject.toml photon-lib
 
       - name: Build Python examples
         working-directory: photonlib-python-examples
@@ -113,3 +122,24 @@ jobs:
             echo $folder
             ./run.sh $folder
           done
+
+  deploy:
+    needs: [test-py, build-python-examples]
+    runs-on: ubuntu-24.04
+    # Only upload on tags
+    if: startsWith(github.ref, 'refs/tags/v')
+
+    steps:
+      - name: Download artifacts
+        uses: actions/download-artifact@v6
+        with:
+          name: dist
+          path: dist/
+
+      - name: Publish package distributions to PyPI
+        uses: pypa/gh-action-pypi-publish@release/v1
+        with:
+          packages-dir: ./dist/
+
+    permissions:
+      id-token: write  # IMPORTANT: this permission is mandatory for trusted publishing