Dedup Python versions (#71)

.github/workflows/ci.yml

@@ -16,38 +16,68 @@ env:
 
 permissions: {}
 
+
 jobs:
+  build-package:
+    name: Build & verify package
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+          persist-credentials: false
+
+      - uses: hynek/build-and-inspect-python-package@v2
+        id: baipp
+
+    outputs:
+      # Used to define the matrix for tests below. The value is based on
+      # packaging metadata (trove classifiers).
+      supported-python-versions: ${{ steps.baipp.outputs.supported_python_classifiers_json_array }}
+
+
   tests:
     name: Tests & Mypy API on ${{ matrix.python-version }}
     runs-on: ubuntu-latest
+    needs: build-package
 
     strategy:
+      fail-fast: false
       matrix:
-        python-version:
-          - "3.7"
-          - "3.8"
-          - "3.9"
-          - "3.10"
-          - "3.11"
-          - "3.12"
-          - "3.13"
+        # Created by the build-and-inspect-python-package action above.
+        python-version: ${{ fromJson(needs.build-package.outputs.supported-python-versions) }}
+
     env:
       PYTHON: ${{ matrix.python-version }}
 
     steps:
-      - uses: actions/checkout@v4
+      - name: Download pre-built packages
+        uses: actions/download-artifact@v4
         with:
-           persist-credentials: false
+          name: Packages
+          path: dist
+      - run: |
+          rm -rf src
+          tar xf dist/*.tar.gz --strip-components=1
       - uses: actions/setup-python@v5
         with:
           python-version: ${{ matrix.python-version }}
           allow-prereleases: true
           cache: pip
 
-      - run: python -Im pip install --upgrade wheel tox
+      - run: python -Im pip install --upgrade tox
 
-      - run: python -Im tox run -f py$(echo $PYTHON | tr -d .)
-      - run: python -Im tox run -e mypy-api
+      - run: >
+          python -Im
+          tox run
+          --installpkg dist/*.whl
+          -f py$(echo $PYTHON | tr -d .)
+      - run: >
+          python -Im
+          tox run
+          --installpkg dist/*.whl
+          -e mypy-api
 
       - name: Upload coverage data
         uses: actions/upload-artifact@v4
@@ -57,6 +87,7 @@ jobs:
           include-hidden-files: true
           if-no-files-found: ignore
 
+
   coverage:
     name: Combine & check coverage
     needs: tests
@@ -69,9 +100,7 @@ jobs:
       - uses: actions/setup-python@v5
         with:
           python-version-file: .python-version-default
-          cache: pip
-
-      - run: python -Im pip install --upgrade coverage[toml]
+      - uses: hynek/setup-cached-uv@v2
 
       - uses: actions/download-artifact@v4
         with:
@@ -80,14 +109,16 @@ jobs:
 
       - name: Combine coverage & fail if it's <100%.
         run: |
-          python -Im coverage combine
-          python -Im coverage html --skip-covered --skip-empty
+          uv tool install coverage
+
+          coverage combine
+          coverage html --skip-covered --skip-empty
 
           # Report and write to summary.
-          python -Im coverage report --format=markdown >> $GITHUB_STEP_SUMMARY
+          coverage report --format=markdown >> $GITHUB_STEP_SUMMARY
 
           # Report again and fail if under 100%.
-          python -Im coverage report --fail-under=100
+          coverage report --fail-under=100
 
       - name: Upload HTML report if check failed.
         uses: actions/upload-artifact@v4
@@ -96,6 +127,7 @@ jobs:
           path: htmlcov
         if: ${{ failure() }}
 
+
   mypy-pkg:
     name: Mypy Codebase
     runs-on: ubuntu-latest
@@ -113,6 +145,7 @@ jobs:
 
       - run: python -Im tox run -e mypy-pkg
 
+
   docs:
     name: Build docs & run doctests
     runs-on: ubuntu-latest
@@ -129,6 +162,7 @@ jobs:
 
       - run: python -Im tox run -e docs
 
+
   install-dev:
     name: Verify dev env
     runs-on: ${{ matrix.os }}