[ci] Add the native ESP8266 compile smoke test (#19714)

.github/actions/cache-arduino8266/action.yml

@@ -0,0 +1,39 @@
+name: Cache Arduino ESP8266
+description: >
+  Resolve the pinned Arduino core and xtensa toolchain versions and cache the
+  native ESP8266 install (~110 MB framework + toolchain; no ccache store, the
+  seed job saves before any compile runs). Exports
+  ESPHOME_ARDUINO8266_PREFIX to the job so every later step installs into
+  the cached path; the Python venv must already be restored. Mirrors
+  cache-esp-idf: only dev-branch pushes write the shared cache, everything
+  else restores.
+runs:
+  using: composite
+  steps:
+    - name: Resolve the native toolchain cache key
+      # Versions are pinned in code, not a hashable file; resolve them so a
+      # bump changes the cache key. Assignment form so errexit catches a
+      # resolver failure.
+      id: version
+      shell: bash
+      run: |
+        # One owner for the install prefix: exported here and referenced by
+        # the cache steps below via env, so the caller's install and the
+        # cached path cannot diverge.
+        echo "ESPHOME_ARDUINO8266_PREFIX=$HOME/.esphome-arduino8266" >> "$GITHUB_ENV"
+        . venv/bin/activate
+        key=$(python -c 'from esphome.components.esp8266 import RECOMMENDED_ARDUINO_FRAMEWORK_VERSION as f; from esphome.arduino8266.framework import TOOLCHAIN_VERSION as t; print(f"{f}-{t}")')
+        [ -n "$key" ] || exit 1
+        echo "key=$key" >> "$GITHUB_OUTPUT"
+    - name: Cache the native toolchain (write on dev)
+      if: github.ref == 'refs/heads/dev'
+      uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
+      with:
+        path: ${{ env.ESPHOME_ARDUINO8266_PREFIX }}
+        key: ${{ runner.os }}-esp8266-native-${{ steps.version.outputs.key }}
+    - name: Restore the native toolchain (off dev)
+      if: github.ref != 'refs/heads/dev'
+      uses: actions/cache/restore@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
+      with:
+        path: ${{ env.ESPHOME_ARDUINO8266_PREFIX }}
+        key: ${{ runner.os }}-esp8266-native-${{ steps.version.outputs.key }}

.github/workflows/ci.yml

@@ -102,6 +102,8 @@ jobs:
       device-builder: ${{ steps.determine.outputs.device-builder }}
       esp32-platformio: ${{ steps.determine.outputs.esp32-platformio }}
       esp32-platformio-components: ${{ steps.determine.outputs.esp32-platformio-components }}
+      esp8266-native: ${{ steps.determine.outputs.esp8266-native }}
+      esp8266-native-components: ${{ steps.determine.outputs.esp8266-native-components }}
       changed-components: ${{ steps.determine.outputs.changed-components }}
       changed-components-with-tests: ${{ steps.determine.outputs.changed-components-with-tests }}
       directly-changed-components-with-tests: ${{ steps.determine.outputs.directly-changed-components-with-tests }}
@@ -165,6 +167,8 @@ jobs:
           echo "device-builder=$(echo "$output" | jq -r '.device_builder')" >> $GITHUB_OUTPUT
           echo "esp32-platformio=$(echo "$output" | jq -r '.esp32_platformio')" >> $GITHUB_OUTPUT
           echo "esp32-platformio-components=$(echo "$output" | jq -r '.esp32_platformio_components')" >> $GITHUB_OUTPUT
+          echo "esp8266-native=$(echo "$output" | jq -r '.esp8266_native')" >> $GITHUB_OUTPUT
+          echo "esp8266-native-components=$(echo "$output" | jq -r '.esp8266_native_components')" >> $GITHUB_OUTPUT
           echo "changed-components=$(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')" >> $GITHUB_OUTPUT
@@ -183,6 +187,32 @@ jobs:
           path: .temp/components_graph.json
           key: components-graph-${{ hashFiles('esphome/components/**/*.py') }}
 
+  seed-esp8266-native-cache:
+    name: Seed the esp8266 native toolchain cache
+    runs-on: ubuntu-24.04
+    needs:
+      - common
+    # PR-branch cache saves are invisible to other PRs, so dev pushes seed
+    # the shared entry test-esp8266-native restores. Only dev: the composite
+    # action saves nowhere else, so a beta/release push would download the
+    # toolchain and discard it.
+    if: github.event_name == 'push' && github.ref == 'refs/heads/dev'
+    timeout-minutes: 15
+    steps:
+      - name: Check out code from GitHub
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - name: Restore Python
+        uses: ./.github/actions/restore-python
+        with:
+          python-version: ${{ env.DEFAULT_PYTHON }}
+          cache-key: ${{ needs.common.outputs.cache-key }}
+      - name: Cache the native toolchain
+        uses: ./.github/actions/cache-arduino8266
+      - name: Install the native toolchain
+        run: |
+          . venv/bin/activate
+          python -c "from esphome.arduino8266.framework import check_and_install; from esphome.components.esp8266 import RECOMMENDED_ARDUINO_FRAMEWORK_VERSION; check_and_install(RECOMMENDED_ARDUINO_FRAMEWORK_VERSION)"
+
   ci-custom:
     name: Run script/ci-custom
     runs-on: ubuntu-24.04
@@ -1237,7 +1267,7 @@ jobs:
 
           # compile validates config first, so a separate config pass is
           # redundant for this smoke test. ESP-IDF framework via PlatformIO:
-          python3 script/test_build_components.py -e compile -t esp32-idf -c "$TEST_COMPONENTS" -f --toolchain platformio
+          python3 script/test_build_components.py -e compile -t esp32-idf -c "$TEST_COMPONENTS" -f --toolchain platformio --fail-on-no-tests
 
           echo ""
           echo "ESP-IDF-via-PlatformIO build passed! Starting Arduino smoke test..."
@@ -1246,6 +1276,40 @@ jobs:
           # Arduino framework via PlatformIO (only components with an esp32-ard test are built):
           python3 script/test_build_components.py -e compile -t esp32-ard -c "$TEST_COMPONENTS" -f --toolchain platformio
 
+  test-esp8266-native:
+    name: Test esp8266 components with the native toolchain
+    runs-on: ubuntu-24.04
+    needs:
+      - common
+      - determine-jobs
+    if: github.event_name == 'pull_request' && needs.determine-jobs.outputs.esp8266-native == 'true'
+    env:
+      # Computed by script/determine-jobs.py (ESP8266_NATIVE_TEST_COMPONENTS)
+      TEST_COMPONENTS: ${{ needs.determine-jobs.outputs.esp8266-native-components }}
+    steps:
+      - name: Check out code from GitHub
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+
+      - name: Restore Python
+        uses: ./.github/actions/restore-python
+        with:
+          python-version: ${{ env.DEFAULT_PYTHON }}
+          cache-key: ${{ needs.common.outputs.cache-key }}
+
+      - name: Cache the native toolchain
+        uses: ./.github/actions/cache-arduino8266
+
+      - name: Run native toolchain compile test
+        run: |
+          . venv/bin/activate
+
+          echo "Testing components: $TEST_COMPONENTS"
+          echo ""
+
+          # ESP8266 Arduino built directly (no PlatformIO); compile validates
+          # config first, so a separate config pass is redundant.
+          python3 script/test_build_components.py -e compile -t esp8266-ard -c "$TEST_COMPONENTS" -f --toolchain arduino --fail-on-no-tests
+
   device-builder:
     name: Test downstream esphome/device-builder
     runs-on: ubuntu-24.04
@@ -1608,6 +1672,7 @@ jobs:
     needs:
       - common
       - seed-apt-cache
+      - seed-esp8266-native-cache
       - determine-jobs
       - ci-custom
       - pylint
@@ -1623,6 +1688,7 @@ jobs:
       - clang-tidy-esp32-variants
       - test-build-components-split
       - test-esp32-platformio
+      - test-esp8266-native
       - device-builder
       - memory-impact-target-branch
       - memory-impact-pr-branch

script/determine-jobs.py

@@ -50,6 +50,7 @@ from __future__ import annotations
 
 import argparse
 from collections import Counter
+from collections.abc import Callable
 from enum import StrEnum
 from functools import cache
 import json
@@ -520,48 +521,69 @@ ESP32_PLATFORMIO_TEST_COMPONENTS = frozenset(
     }
 )
 
+# Shared by every toolchain smoke-test job: the base config and the bus
+# packages each generated build includes
+_SMOKE_HARNESS_TRIGGER_PATH_PREFIXES = ("tests/test_build_components/",)
+
 # Path prefixes whose changes always trigger the PlatformIO compile test:
 # anything under esphome/platformio/ (the PlatformIO runner / toolchain that
 # drives every PlatformIO build). The esp32 platform component is already in
 # ESP32_PLATFORMIO_TEST_COMPONENTS, so its changes are covered by the normal
 # component-narrowing path.
-ESP32_PLATFORMIO_TRIGGER_PATH_PREFIXES = ("esphome/platformio/",)
+ESP32_PLATFORMIO_TRIGGER_PATH_PREFIXES = (
+    "esphome/platformio/",
+    *_SMOKE_HARNESS_TRIGGER_PATH_PREFIXES,
+)
 
 # Standalone files that, when changed, trigger the PlatformIO compile test:
 #   - esphome/build_gen/platformio.py -- the PlatformIO build generator
 #   - script/test_build_components.py -- the harness the job invokes
 #   - .github/workflows/ci.yml -- the job's own definition
-ESP32_PLATFORMIO_TRIGGER_FILES = frozenset(
+# Shared by every toolchain smoke-test job: the harness it invokes and the
+# workflow that defines it
+_SMOKE_HARNESS_TRIGGER_FILES = frozenset(
     {
-        "esphome/build_gen/platformio.py",
         "script/test_build_components.py",
         ".github/workflows/ci.yml",
     }
 )
 
+ESP32_PLATFORMIO_TRIGGER_FILES = _SMOKE_HARNESS_TRIGGER_FILES | {
+    "esphome/build_gen/platformio.py",
+}
+
+
+def _path_or_file_trigger(
+    files: list[str],
+    trigger_files: frozenset[str],
+    trigger_prefixes: tuple[str, ...],
+) -> bool:
+    """Whether any changed file matches the given infrastructure triggers."""
+    return any(
+        file in trigger_files or file.startswith(trigger_prefixes) for file in files
+    )
+
+
+@cache
+def _cached_components_closure(files: tuple[str, ...]) -> frozenset[str]:
+    """Dependency closure of the changed components; cached because the
+    walk is expensive and every smoke-test job asks for the same list."""
+    component_files = [f for f in files if filter_component_and_test_files(f)]
+    return frozenset(get_components_with_dependencies(component_files, True))
+
 
 def _esp32_platformio_path_or_file_trigger(files: list[str]) -> bool:
     """Whether any changed file is a PlatformIO infrastructure / harness trigger."""
-    for file in files:
-        if file in ESP32_PLATFORMIO_TRIGGER_FILES:
-            return True
-        if any(
-            file.startswith(prefix) for prefix in ESP32_PLATFORMIO_TRIGGER_PATH_PREFIXES
-        ):
-            return True
-    return False
+    return _path_or_file_trigger(
+        files, ESP32_PLATFORMIO_TRIGGER_FILES, ESP32_PLATFORMIO_TRIGGER_PATH_PREFIXES
+    )
 
 
 def _esp_idf_infra_changed(files: list[str]) -> bool:
     """Whether any changed file is ESP-IDF build/runner infrastructure."""
-    for file in files:
-        if file in ESP_IDF_INFRA_TRIGGER_FILES:
-            return True
-        if any(
-            file.startswith(prefix) for prefix in ESP_IDF_INFRA_TRIGGER_PATH_PREFIXES
-        ):
-            return True
-    return False
+    return _path_or_file_trigger(
+        files, ESP_IDF_INFRA_TRIGGER_FILES, ESP_IDF_INFRA_TRIGGER_PATH_PREFIXES
+    )
 
 
 def esp32_platformio_components_to_test(branch: str | None = None) -> list[str]:
@@ -599,15 +621,23 @@ def esp32_platformio_components_to_test(branch: str | None = None) -> list[str]:
     Returns:
         Sorted list of component names to compile.
     """
+    return _toolchain_components_to_test(
+        branch, ESP32_PLATFORMIO_TEST_COMPONENTS, _esp32_platformio_path_or_file_trigger
+    )
+
+
+def _toolchain_components_to_test(
+    branch: str | None,
+    test_set: frozenset[str],
+    infra_trigger: Callable[[list[str]], bool],
+) -> list[str]:
+    """The shared narrowing rule for the per-toolchain smoke-test jobs."""
     files = changed_files(branch)
 
-    if core_changed(files) or _esp32_platformio_path_or_file_trigger(files):
-        return sorted(ESP32_PLATFORMIO_TEST_COMPONENTS)
+    if core_changed(files) or infra_trigger(files):
+        return sorted(test_set)
 
-    component_files = [f for f in files if filter_component_and_test_files(f)]
-    changed = get_components_with_dependencies(component_files, True)
-
-    return sorted(ESP32_PLATFORMIO_TEST_COMPONENTS & set(changed))
+    return sorted(test_set & _cached_components_closure(tuple(files)))
 
 
 def should_run_esp32_platformio(branch: str | None = None) -> bool:
@@ -628,6 +658,79 @@ def should_run_esp32_platformio(branch: str | None = None) -> bool:
     return bool(esp32_platformio_components_to_test(branch))
 
 
+# The `--toolchain arduino` smoke-test set: covers the core, the bundled and
+# converted registry libraries, and the waveform path.
+ESP8266_NATIVE_TEST_COMPONENTS = frozenset(
+    {
+        "esp8266",
+        "api",
+        "web_server",
+        "captive_portal",
+        "mqtt",
+        "esp8266_pwm",
+        "neopixelbus",
+        "bme280_i2c",
+        "uart",
+    }
+)
+
+# Infrastructure whose changes always trigger the native ESP8266
+# compile test
+ESP8266_NATIVE_TRIGGER_PATH_PREFIXES = (
+    "esphome/arduino8266/",
+    "esphome/arduino/",
+    "esphome/build_helpers/",
+    *_SMOKE_HARNESS_TRIGGER_PATH_PREFIXES,
+)
+# Shared library-conversion modules every native build imports; espidf-only
+# infra (build_gen/espidf.py) deliberately stays out of the esp8266 set.
+_NATIVE_SHARED_TRIGGER_FILES = frozenset(
+    {
+        "esphome/framework_helpers.py",
+        "esphome/platformio/library.py",
+        "esphome/platformio/extra_script.py",
+    }
+)
+# Tripwire: the shared modules must stay in the ESP-IDF trigger set too
+# (now defined in clang_tidy_hash), or its smoke test silently skips them
+assert _NATIVE_SHARED_TRIGGER_FILES <= ESP_IDF_INFRA_TRIGGER_FILES
+ESP8266_NATIVE_TRIGGER_FILES = (
+    _NATIVE_SHARED_TRIGGER_FILES
+    | _SMOKE_HARNESS_TRIGGER_FILES
+    | {
+        "esphome/build_gen/arduino8266.py",
+        "esphome/build_gen/build_tool.py",
+        "esphome/components/esp8266/build_surgery.py",
+        "esphome/components/esp8266/boards.py",
+        "esphome/platformio/registry.py",
+        # esp8266/__init__.py imports copy_ccache_script from it
+        "esphome/platformio/toolchain.py",
+        ".github/actions/cache-arduino8266/action.yml",
+    }
+)
+
+
+def _esp8266_native_path_or_file_trigger(files: list[str]) -> bool:
+    """Whether any changed file is native-ESP8266 infrastructure / harness."""
+    # base_python_changed covers the top-level esphome/*.py modules the
+    # native backend imports directly (framework_helpers, helpers, writer,
+    # __main__); without it a change there would silently skip this job.
+    # base_python_changed is deliberately broad (any top-level esphome/*.py)
+    # as belt-and-braces while the backend is new; narrow it to the modules
+    # the backend imports once the toolchain has soaked a few releases
+    return base_python_changed(files) or _path_or_file_trigger(
+        files, ESP8266_NATIVE_TRIGGER_FILES, ESP8266_NATIVE_TRIGGER_PATH_PREFIXES
+    )
+
+
+def esp8266_native_components_to_test(branch: str | None = None) -> list[str]:
+    """Subset of ``ESP8266_NATIVE_TEST_COMPONENTS`` the job needs to
+    compile (same narrowing as ``esp32_platformio_components_to_test``)."""
+    return _toolchain_components_to_test(
+        branch, ESP8266_NATIVE_TEST_COMPONENTS, _esp8266_native_path_or_file_trigger
+    )
+
+
 def determine_cpp_unit_tests(
     branch: str | None = None,
 ) -> tuple[bool, list[str]]:
@@ -1226,6 +1329,8 @@ def main() -> None:
         run_device_builder = True
         esp32_platformio_components = sorted(ESP32_PLATFORMIO_TEST_COMPONENTS)
         run_esp32_platformio = True
+        esp8266_native_components = sorted(ESP8266_NATIVE_TEST_COMPONENTS)
+        run_esp8266_native = True
     else:
         integration_run_all, integration_test_files = determine_integration_tests(
             args.branch
@@ -1237,6 +1342,8 @@ def main() -> None:
         run_device_builder = should_run_device_builder(args.branch)
         esp32_platformio_components = esp32_platformio_components_to_test(args.branch)
         run_esp32_platformio = bool(esp32_platformio_components)
+        esp8266_native_components = esp8266_native_components_to_test(args.branch)
+        run_esp8266_native = bool(esp8266_native_components)
     run_integration, integration_test_buckets = _compute_integration_test_buckets(
         integration_run_all, integration_test_files
     )
@@ -1432,6 +1539,8 @@ def main() -> None:
         "device_builder": run_device_builder,
         "esp32_platformio": run_esp32_platformio,
         "esp32_platformio_components": ",".join(esp32_platformio_components),
+        "esp8266_native": run_esp8266_native,
+        "esp8266_native_components": ",".join(esp8266_native_components),
         "changed_components": changed_components,
         "changed_components_with_tests": changed_components_with_tests,
         "directly_changed_components_with_tests": list(directly_changed_with_tests),

script/test_build_components.py

@@ -1027,6 +1027,7 @@ def test_components(
     isolated_components: set[str] | None = None,
     base_only: bool = False,
     toolchain: str | None = None,
+    fail_on_no_tests: bool = False,
 ) -> int:
     """Test components with optional intelligent grouping.
 
@@ -1061,20 +1062,32 @@ def test_components(
     # toolchain build.
     include_validate = esphome_command != "compile"
 
-    # Find all component tests
+    # A blank pattern list would slide into the reference-baseline
+    # fallback and exit green while building nothing
+    if fail_on_no_tests and not any(component_patterns):
+        print("No components requested (blank component list)")
+        return 1
+
+    # Find all component tests; remember which components each pattern
+    # (wildcards included) matched, for the deferred no-tests accounting
     all_tests = {}
+    pattern_components: dict[str, set[str]] = {}
     for pattern in component_patterns:
         # Skip empty patterns (happens when components list is empty string)
         if not pattern:
             continue
-        all_tests.update(
-            find_component_tests(
-                tests_dir, pattern, base_only, include_validate=include_validate
-            )
+        found = find_component_tests(
+            tests_dir, pattern, base_only, include_validate=include_validate
         )
+        pattern_components[pattern] = set(found)
+        all_tests.update(found)
+
+    if fail_on_no_tests and not all_tests:
+        # Nothing matched: fail before the synthetic baseline spends a
+        # compile reporting success on nothing
+        print(f"No components found matching: {component_patterns}")
+        return 1
 
-    # If no components found, build a reference configuration for baseline comparison
-    # Create a synthetic "empty" component test that will build just the base config
     if not all_tests:
         print(f"No components found matching: {component_patterns}")
         print(
@@ -1178,6 +1191,23 @@ def test_components(
                         toolchain=toolchain,
                     )
 
+    silent: list[str] = []
+    if fail_on_no_tests:
+        # A green run that built nothing for a requested pattern must not
+        # pass CI. Per pattern so one silent pattern cannot hide behind
+        # the others; opt-in because some legs legitimately match nothing;
+        # deferred past the summary so reproduce commands still print.
+        built = {c for r in test_results for c in r.components}
+        # A pattern is silent when it matched no fixture, or when none of
+        # its matched components produced a build (wildcards included)
+        silent = [
+            p
+            for p in component_patterns
+            if p and not (pattern_components.get(p, set()) & built)
+        ]
+        if silent:
+            print(f"No tests ran for requested pattern(s): {', '.join(silent)}")
+
     # Separate results into passed and failed
     passed_results = [r for r in test_results if r.success]
     failed_results = [r for r in test_results if not r.success]
@@ -1209,7 +1239,7 @@ def test_components(
     if os.environ.get("GITHUB_STEP_SUMMARY"):
         write_github_summary(test_results, toolchain=toolchain)
 
-    if failed_results:
+    if failed_results or silent:
         return 1
 
     return 0
@@ -1264,6 +1294,12 @@ def main() -> int:
         "--toolchain",
         help="Select toolchain for compiling.",
     )
+    parser.add_argument(
+        "--fail-on-no-tests",
+        action="store_true",
+        help="Exit non-zero when no test matched (for CI legs whose "
+        "components must all have fixtures)",
+    )
 
     args = parser.parse_args()
 
@@ -1282,6 +1318,7 @@ def main() -> int:
         continue_on_fail=args.continue_on_fail,
         enable_grouping=not args.no_grouping,
         isolated_components=isolated_components,
+        fail_on_no_tests=args.fail_on_no_tests,
         base_only=args.base_only,
         toolchain=args.toolchain,
     )

tests/script/test_determine_jobs.py

@@ -78,6 +78,17 @@ def mock_esp32_platformio_components_to_test() -> Generator[Mock, None, None]:
         yield mock
 
 
+@pytest.fixture
+def mock_esp8266_native_components_to_test() -> Generator[Mock, None, None]:
+    """Mock esp8266_native_components_to_test from determine_jobs.
+
+    main() drives both the ``esp8266_native`` boolean output and the
+    ``esp8266_native_components`` CSV from this one function.
+    """
+    with patch.object(determine_jobs, "esp8266_native_components_to_test") as mock:
+        yield mock
+
+
 @pytest.fixture
 def mock_determine_cpp_unit_tests() -> Generator[Mock, None, None]:
     """Mock determine_cpp_unit_tests from helpers."""
@@ -106,6 +117,7 @@ def clear_determine_jobs_caches() -> None:
     """Clear all cached functions before each test."""
     determine_jobs._is_clang_tidy_full_scan.cache_clear()
     determine_jobs._component_has_tests.cache_clear()
+    determine_jobs._cached_components_closure.cache_clear()
 
 
 def test_main_all_tests_should_run(
@@ -116,6 +128,7 @@ def test_main_all_tests_should_run(
     mock_should_run_import_time: Mock,
     mock_should_run_device_builder: Mock,
     mock_esp32_platformio_components_to_test: Mock,
+    mock_esp8266_native_components_to_test: Mock,
     mock_changed_files: Mock,
     mock_determine_cpp_unit_tests: Mock,
     capsys: pytest.CaptureFixture[str],
@@ -132,6 +145,7 @@ def test_main_all_tests_should_run(
     mock_should_run_import_time.return_value = True
     mock_should_run_device_builder.return_value = True
     mock_esp32_platformio_components_to_test.return_value = ["api", "esp32"]
+    mock_esp8266_native_components_to_test.return_value = ["api", "logger"]
     mock_determine_cpp_unit_tests.return_value = (False, ["wifi", "api", "sensor"])
 
     # Mock changed_files to return non-component files (to avoid memory impact)
@@ -208,6 +222,8 @@ def test_main_all_tests_should_run(
     assert output["device_builder"] is True
     assert output["esp32_platformio"] is True
     assert output["esp32_platformio_components"] == "api,esp32"
+    assert output["esp8266_native"] is True
+    assert output["esp8266_native_components"] == "api,logger"
     assert output["changed_components"] == ["wifi", "api", "sensor"]
     # changed_components_with_tests will only include components that actually have test files
     assert "changed_components_with_tests" in output
@@ -244,6 +260,7 @@ def test_main_no_tests_should_run(
     mock_should_run_import_time: Mock,
     mock_should_run_device_builder: Mock,
     mock_esp32_platformio_components_to_test: Mock,
+    mock_esp8266_native_components_to_test: Mock,
     mock_changed_files: Mock,
     mock_determine_cpp_unit_tests: Mock,
     capsys: pytest.CaptureFixture[str],
@@ -260,6 +277,7 @@ def test_main_no_tests_should_run(
     mock_should_run_import_time.return_value = False
     mock_should_run_device_builder.return_value = False
     mock_esp32_platformio_components_to_test.return_value = []
+    mock_esp8266_native_components_to_test.return_value = []
     mock_determine_cpp_unit_tests.return_value = (False, [])
 
     # Mock changed_files to return no component files
@@ -302,6 +320,8 @@ def test_main_no_tests_should_run(
     assert output["device_builder"] is False
     assert output["esp32_platformio"] is False
     assert output["esp32_platformio_components"] == ""
+    assert output["esp8266_native"] is False
+    assert output["esp8266_native_components"] == ""
     assert output["changed_components"] == []
     assert output["changed_components_with_tests"] == []
     assert output["component_test_count"] == 0
@@ -997,6 +1017,9 @@ _ESP32_PLATFORMIO_FULL_LIST_FILES = [
     # Workflow / harness files
     ["script/test_build_components.py"],
     [".github/workflows/ci.yml"],
+    # The base config and bus packages every generated build includes
+    ["tests/test_build_components/build_components_base.esp32-idf.yaml"],
+    ["tests/test_build_components/common/uart/esp32-idf.yaml"],
 ]
 
 
@@ -3151,6 +3174,81 @@ def test_memory_impact_elf_layouts_are_found(tmp_path: Path) -> None:
         assert find_elf_path(build_path) == elf, f"{platform} ELF not found"
 
 
+@pytest.mark.parametrize(
+    "changed",
+    [
+        "esphome/arduino8266/framework.py",
+        "esphome/build_gen/arduino8266.py",
+        "esphome/components/esp8266/build_surgery.py",
+        # Shared modules the native build depends on
+        "esphome/build_helpers/idedata.py",
+        "esphome/platformio/library.py",
+        # Top-level esphome/*.py modules the backend imports directly
+        "esphome/framework_helpers.py",
+        "esphome/writer.py",
+        # esp8266/__init__.py imports copy_ccache_script from it
+        "esphome/platformio/toolchain.py",
+        # The composite cache action must not ship unexercised
+        ".github/actions/cache-arduino8266/action.yml",
+        # The base config and bus packages every generated build includes
+        "tests/test_build_components/build_components_base.esp8266-ard.yaml",
+        "tests/test_build_components/common/uart/esp8266-ard.yaml",
+    ],
+)
+def test_esp8266_native_components_full_list_on_infra_change(changed: str) -> None:
+    """Native-ESP8266 infrastructure changes run the full test list."""
+    with (
+        patch.object(determine_jobs, "changed_files", return_value=[changed]),
+        patch.object(
+            determine_jobs,
+            "get_components_with_dependencies",
+            return_value=["wifi"],
+        ),
+    ):
+        result = determine_jobs.esp8266_native_components_to_test()
+        assert result == sorted(determine_jobs.ESP8266_NATIVE_TEST_COMPONENTS)
+
+
+@pytest.mark.parametrize(
+    ("changed_files", "dependency_closure", "expected"),
+    [
+        # Tested component changed -- narrow to the intersection.
+        (
+            ["esphome/components/mqtt/mqtt_client.cpp"],
+            ["mqtt", "json"],
+            ["mqtt"],
+        ),
+        # Components outside the test set return an empty list (job skipped).
+        (
+            ["esphome/components/wifi/wifi_component.cpp"],
+            ["wifi", "network"],
+            [],
+        ),
+        # espidf infrastructure is not an esp8266-native trigger; the
+        # native backend depends on esphome/build_helpers/ instead.
+        (["esphome/build_gen/espidf.py"], [], []),
+        (["esphome/espidf/toolchain.py"], [], []),
+        (["README.md"], [], []),
+    ],
+)
+def test_esp8266_native_components_to_test_narrowing(
+    changed_files: list[str],
+    dependency_closure: list[str],
+    expected: list[str],
+) -> None:
+    """Component changes narrow the native-ESP8266 test list."""
+    with (
+        patch.object(determine_jobs, "changed_files", return_value=changed_files),
+        patch.object(
+            determine_jobs,
+            "get_components_with_dependencies",
+            return_value=dependency_closure,
+        ),
+    ):
+        result = determine_jobs.esp8266_native_components_to_test()
+        assert result == expected
+
+
 def test_compute_integration_test_buckets_no_durations_full_fanout() -> None:
     """Without recorded durations the fan-out stays at the maximum."""
     files = [f"tests/integration/test_{i:03d}.py" for i in range(15)]

tests/script/test_test_build_components.py

@@ -236,3 +236,98 @@ def test_run_grouped_test_closes_group_when_subprocess_raises(
         )
 
     assert "::endgroup::" in capsys.readouterr().out
+
+
+def test_components_empty_match_fails_with_flag(
+    capsys: pytest.CaptureFixture[str],
+) -> None:
+    """Under --fail-on-no-tests, a real component filtered to a platform
+    with no matching test file must not pass CI as a green zero-component
+    compile."""
+    rc = tbc.test_components(
+        ["logger"],
+        "zz-none",
+        "compile",
+        False,
+        enable_grouping=False,
+        fail_on_no_tests=True,
+    )
+    assert rc == 1
+    assert "No tests ran for requested pattern(s): logger" in (capsys.readouterr().out)
+
+
+def test_components_component_with_no_base_file_fails_with_flag(
+    capsys: pytest.CaptureFixture[str],
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    """A component whose fixture matches the platform but whose platform has
+    no base file builds nothing; under the flag that silent zero fails by
+    component name instead of hiding behind other components."""
+    monkeypatch.setattr(tbc, "get_platform_base_files", lambda base_dir: {})
+    rc = tbc.test_components(
+        ["logger"],
+        "esp8266-ard",
+        "compile",
+        False,
+        enable_grouping=False,
+        fail_on_no_tests=True,
+    )
+    assert rc == 1
+    assert "No tests ran for requested pattern(s): logger" in (capsys.readouterr().out)
+
+
+def test_components_blank_list_fails_with_flag(
+    capsys: pytest.CaptureFixture[str],
+) -> None:
+    """A fully blank component list must not slide into the baseline
+    fallback and exit green under the flag."""
+    rc = tbc.test_components(
+        [""], "esp8266-ard", "compile", False, fail_on_no_tests=True
+    )
+    assert rc == 1
+    assert "blank component list" in capsys.readouterr().out
+
+
+def test_components_wildcard_no_match_fails_with_flag(
+    capsys: pytest.CaptureFixture[str],
+) -> None:
+    """A wildcard matching nothing must not degrade to the synthetic
+    baseline build and exit green under the flag."""
+    rc = tbc.test_components(
+        ["zz_no_such*"],
+        "esp8266-ard",
+        "compile",
+        False,
+        enable_grouping=False,
+        fail_on_no_tests=True,
+    )
+    assert rc == 1
+    assert "No components found matching" in capsys.readouterr().out
+
+
+def test_components_empty_match_tolerated_without_flag() -> None:
+    """The esp32-ard smoke leg deliberately builds only the subset with a
+    matching fixture; without the flag an empty match stays green."""
+    assert (
+        tbc.test_components(
+            ["logger"], "zz-none", "compile", False, enable_grouping=False
+        )
+        == 0
+    )
+
+
+def test_components_unknown_component_fails_with_flag(
+    capsys: pytest.CaptureFixture[str],
+) -> None:
+    """A renamed smoke-test component must shrink coverage loudly, not fall
+    into the reference-baseline build."""
+    rc = tbc.test_components(
+        ["no_such_component_xyz"],
+        "esp8266-ard",
+        "compile",
+        False,
+        enable_grouping=False,
+        fail_on_no_tests=True,
+    )
+    assert rc == 1
+    assert "No components found matching" in capsys.readouterr().out