[ci] Run downstream device-builder tests against PR Python code (#16214)

.github/workflows/ci.yml

@@ -136,6 +136,53 @@ jobs:
           if-no-files-found: ignore
           retention-days: 14
 
+  device-builder:
+    name: Test downstream esphome/device-builder
+    runs-on: ubuntu-24.04
+    needs:
+      - common
+      - determine-jobs
+    if: needs.determine-jobs.outputs.device-builder == 'true'
+    steps:
+      - name: Check out esphome (this PR)
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          path: esphome
+      - name: Check out esphome/device-builder
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          repository: esphome/device-builder
+          ref: main
+          path: device-builder
+      - name: Set up Python
+        uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6.2.0
+        with:
+          python-version: "3.13"
+      - name: Set up uv
+        # Mirrors the install shape device-builder's own CI uses
+        # (esphome/device-builder#192): uv replaces pip for the
+        # install step (order-of-magnitude faster on cold boots,
+        # with its own wheel cache). actions/setup-python still
+        # provides the interpreter.
+        uses: astral-sh/setup-uv@08807647e7069bb48b6ef5acd8ec9567f424441b # v8.1.0
+        with:
+          enable-cache: true
+      - name: Install device-builder + esphome from PR
+        # Install device-builder with its esphome + test extras
+        # first so its pinned versions of pytest/etc. land, then
+        # overlay the PR's esphome so the downstream tests run
+        # against this PR's Python code. ``--system`` installs into
+        # the runner's Python instead of a venv.
+        run: |
+          uv pip install --system -e './device-builder[esphome,test]'
+          uv pip install --system -e ./esphome
+      - name: Run device-builder pytest
+        # ``-n auto`` runs under pytest-xdist (matches device-builder's
+        # own CI). No ``--cov`` here -- this is purely a downstream
+        # smoke check against this PR's esphome code.
+        working-directory: device-builder
+        run: pytest -q -n auto --maxfail=5 --durations=10 --no-cov --ignore=tests/benchmarks
+
   pytest:
     name: Run pytest
     strategy:
@@ -204,6 +251,7 @@ jobs:
       clang-tidy-mode: ${{ steps.determine.outputs.clang-tidy-mode }}
       python-linters: ${{ steps.determine.outputs.python-linters }}
       import-time: ${{ steps.determine.outputs.import-time }}
+      device-builder: ${{ steps.determine.outputs.device-builder }}
       changed-components: ${{ steps.determine.outputs.changed-components }}
       changed-components-with-tests: ${{ steps.determine.outputs.changed-components-with-tests }}
       directly-changed-components-with-tests: ${{ steps.determine.outputs.directly-changed-components-with-tests }}
@@ -247,6 +295,7 @@ jobs:
           echo "clang-tidy-mode=$(echo "$output" | jq -r '.clang_tidy_mode')" >> $GITHUB_OUTPUT
           echo "python-linters=$(echo "$output" | jq -r '.python_linters')" >> $GITHUB_OUTPUT
           echo "import-time=$(echo "$output" | jq -r '.import_time')" >> $GITHUB_OUTPUT
+          echo "device-builder=$(echo "$output" | jq -r '.device_builder')" >> $GITHUB_OUTPUT
           echo "changed-components=$(echo "$output" | jq -c '.changed_components')" >> $GITHUB_OUTPUT
           echo "changed-components-with-tests=$(echo "$output" | jq -c '.changed_components_with_tests')" >> $GITHUB_OUTPUT
           echo "directly-changed-components-with-tests=$(echo "$output" | jq -c '.directly_changed_components_with_tests')" >> $GITHUB_OUTPUT
@@ -1063,6 +1112,7 @@ jobs:
       - clang-tidy-nosplit
       - clang-tidy-split
       - determine-jobs
+      - device-builder
       - test-build-components-split
       - pre-commit-ci-lite
       - memory-impact-target-branch