Merge remote-tracking branch 'upstream/fix-slow-serial-log-test' into integration

# Conflicts:
#	.github/workflows/ci.yml
#	esphome/components/esp32_ble_server/ble_server.cpp
#	esphome/components/mqtt/mqtt_backend_esp32.cpp
#	script/cpp_benchmark.py
#	script/determine-jobs.py

.github/workflows/ci.yml

@@ -316,7 +316,9 @@ jobs:
     needs:
       - common
       - determine-jobs
-    if: github.event_name == 'pull_request' && needs.determine-jobs.outputs.benchmarks == 'true'
+    if: >-
+      (github.event_name == 'push' && github.ref_name == 'dev') ||
+      (github.event_name == 'pull_request' && needs.determine-jobs.outputs.benchmarks == 'true')
     steps:
       - name: Check out code from GitHub
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2

README.md

@@ -1,4 +1,4 @@
-# ESPHome [![Discord Chat](https://img.shields.io/discord/429907082951524364.svg)](https://discord.gg/KhAMKrd) [![GitHub release](https://img.shields.io/github/release/esphome/esphome.svg)](https://GitHub.com/esphome/esphome/releases/)
+# ESPHome [![Discord Chat](https://img.shields.io/discord/429907082951524364.svg)](https://discord.gg/KhAMKrd) [![GitHub release](https://img.shields.io/github/release/esphome/esphome.svg)](https://GitHub.com/esphome/esphome/releases/) [![CodSpeed](https://img.shields.io/endpoint?url=https://codspeed.io/badge.json)](https://codspeed.io/esphome/esphome)
 
 <a href="https://esphome.io/">
   <picture>

esphome/components/ee895/ee895.cpp

@@ -24,7 +24,7 @@ void EE895Component::setup() {
   this->read(serial_number, 20);
 
   crc16_check = (serial_number[19] << 8) + serial_number[18];
-  if (crc16_check != calc_crc16_(serial_number, 19)) {
+  if (crc16_check != calc_crc16_(serial_number, 18)) {
     this->error_code_ = CRC_CHECK_FAILED;
     this->mark_failed();
     return;
@@ -84,7 +84,7 @@ void EE895Component::write_command_(uint16_t addr, uint16_t reg_cnt) {
   address[2] = addr & 0xFF;
   address[3] = (reg_cnt >> 8) & 0xFF;
   address[4] = reg_cnt & 0xFF;
-  crc16 = calc_crc16_(address, 6);
+  crc16 = calc_crc16_(address, 5);
   address[5] = crc16 & 0xFF;
   address[6] = (crc16 >> 8) & 0xFF;
   this->write(address, 7);
@@ -95,7 +95,7 @@ float EE895Component::read_float_() {
   uint8_t i2c_response[8];
   this->read(i2c_response, 8);
   crc16_check = (i2c_response[7] << 8) + i2c_response[6];
-  if (crc16_check != calc_crc16_(i2c_response, 7)) {
+  if (crc16_check != calc_crc16_(i2c_response, 6)) {
     this->error_code_ = CRC_CHECK_FAILED;
     this->status_set_warning();
     return 0;
@@ -107,12 +107,9 @@ float EE895Component::read_float_() {
 }
 
 uint16_t EE895Component::calc_crc16_(const uint8_t buf[], uint8_t len) {
-  uint8_t crc_check_buf[22];
-  for (int i = 0; i < len; i++) {
-    crc_check_buf[i + 1] = buf[i];
-  }
-  crc_check_buf[0] = this->address_;
-  return crc16(crc_check_buf, len);
+  uint8_t addr = this->address_;
+  uint16_t crc = crc16(&addr, 1);
+  return crc16(buf, len, crc);
 }
 }  // namespace ee895
 }  // namespace esphome

esphome/components/esp32_ble_server/ble_characteristic.cpp

@@ -16,13 +16,9 @@ BLECharacteristic::~BLECharacteristic() {
   for (auto *descriptor : this->descriptors_) {
     delete descriptor;  // NOLINT(cppcoreguidelines-owning-memory)
   }
-  vSemaphoreDelete(this->set_value_lock_);
 }
 
 BLECharacteristic::BLECharacteristic(const ESPBTUUID uuid, uint32_t properties) : uuid_(uuid) {
-  this->set_value_lock_ = xSemaphoreCreateBinary();
-  xSemaphoreGive(this->set_value_lock_);
-
   this->properties_ = (esp_gatt_char_prop_t) 0;
 
   this->set_broadcast_property((properties & PROPERTY_BROADCAST) != 0);
@@ -35,11 +31,7 @@ BLECharacteristic::BLECharacteristic(const ESPBTUUID uuid, uint32_t properties)
 
 void BLECharacteristic::set_value(ByteBuffer buffer) { this->set_value(buffer.get_data()); }
 
-void BLECharacteristic::set_value(std::vector<uint8_t> &&buffer) {
-  xSemaphoreTake(this->set_value_lock_, 0L);
-  this->value_ = std::move(buffer);
-  xSemaphoreGive(this->set_value_lock_);
-}
+void BLECharacteristic::set_value(std::vector<uint8_t> &&buffer) { this->value_ = std::move(buffer); }
 
 void BLECharacteristic::set_value(std::initializer_list<uint8_t> data) {
   this->set_value(std::vector<uint8_t>(data));  // Delegate to move overload

esphome/components/esp32_ble_server/ble_characteristic.h

@@ -16,8 +16,6 @@
 #include <esp_gattc_api.h>
 #include <esp_gatts_api.h>
 #include <esp_bt_defs.h>
-#include <freertos/FreeRTOS.h>
-#include <freertos/semphr.h>
 
 namespace esphome {
 namespace esp32_ble_server {
@@ -84,8 +82,6 @@ class BLECharacteristic {
 
   uint16_t value_read_offset_{0};
   std::vector<uint8_t> value_;
-  SemaphoreHandle_t set_value_lock_;
-
   std::vector<BLEDescriptor *> descriptors_;
 
   struct ClientNotificationEntry {

esphome/components/esp32_ble_server/ble_server.cpp

@@ -39,11 +39,11 @@ void BLEServer::loop() {
       // Start all services that are pending to start
       if (!this->services_to_start_.empty()) {
         size_t write_idx = 0;
-        for (auto service : this->services_to_start_) {
+        for (auto *service : this->services_to_start_) {
           if (service->is_created()) {
             service->start();  // Needs to be called once per characteristic in the service
           }
-          // Keep services still pending (drop those that are starting or running)
+          // Remove services that have started or are starting
           if (!service->is_starting() && !service->is_running()) {
             this->services_to_start_[write_idx++] = service;
           }

esphome/components/hdc2010/hdc2010.cpp

@@ -7,50 +7,36 @@ namespace hdc2010 {
 
 static const char *const TAG = "hdc2010";
 
-static const uint8_t HDC2010_ADDRESS = 0x40;  // 0b1000000 or 0b1000001 from datasheet
-static const uint8_t HDC2010_CMD_CONFIGURATION_MEASUREMENT = 0x8F;
-static const uint8_t HDC2010_CMD_START_MEASUREMENT = 0xF9;
-static const uint8_t HDC2010_CMD_TEMPERATURE_LOW = 0x00;
-static const uint8_t HDC2010_CMD_TEMPERATURE_HIGH = 0x01;
-static const uint8_t HDC2010_CMD_HUMIDITY_LOW = 0x02;
-static const uint8_t HDC2010_CMD_HUMIDITY_HIGH = 0x03;
-static const uint8_t CONFIG = 0x0E;
-static const uint8_t MEASUREMENT_CONFIG = 0x0F;
+// Register addresses
+static constexpr uint8_t REG_TEMPERATURE_LOW = 0x00;
+static constexpr uint8_t REG_TEMPERATURE_HIGH = 0x01;
+static constexpr uint8_t REG_HUMIDITY_LOW = 0x02;
+static constexpr uint8_t REG_HUMIDITY_HIGH = 0x03;
+static constexpr uint8_t REG_RESET_DRDY_INT_CONF = 0x0E;
+static constexpr uint8_t REG_MEASUREMENT_CONF = 0x0F;
+
+// REG_MEASUREMENT_CONF (0x0F) bit masks
+static constexpr uint8_t MEAS_TRIG = 0x01;       // Bit 0: measurement trigger
+static constexpr uint8_t MEAS_CONF_MASK = 0x06;  // Bits 2:1: measurement mode
+static constexpr uint8_t HRES_MASK = 0x30;       // Bits 5:4: humidity resolution
+static constexpr uint8_t TRES_MASK = 0xC0;       // Bits 7:6: temperature resolution
+
+// REG_RESET_DRDY_INT_CONF (0x0E) bit masks
+static constexpr uint8_t AMM_MASK = 0x70;  // Bits 6:4: auto measurement mode
 
 void HDC2010Component::setup() {
   ESP_LOGCONFIG(TAG, "Running setup");
 
-  const uint8_t data[2] = {
-      0b00000000,  // resolution 14bit for both humidity and temperature
-      0b00000000   // reserved
-  };
-
-  if (!this->write_bytes(HDC2010_CMD_CONFIGURATION_MEASUREMENT, data, 2)) {
-    ESP_LOGW(TAG, "Initial config instruction error");
-    this->status_set_warning();
-    return;
-  }
-
-  // Set measurement mode to temperature and humidity
+  // Set 14-bit resolution for both sensors and measurement mode to temp + humidity
   uint8_t config_contents;
-  this->read_register(MEASUREMENT_CONFIG, &config_contents, 1);
-  config_contents = (config_contents & 0xF9);  // Always set to TEMP_AND_HUMID mode
-  this->write_bytes(MEASUREMENT_CONFIG, &config_contents, 1);
+  this->read_register(REG_MEASUREMENT_CONF, &config_contents, 1);
+  config_contents &= ~(TRES_MASK | HRES_MASK | MEAS_CONF_MASK);  // 14-bit temp, 14-bit humidity, temp+humidity mode
+  this->write_bytes(REG_MEASUREMENT_CONF, &config_contents, 1);
 
-  // Set rate to manual
-  this->read_register(CONFIG, &config_contents, 1);
-  config_contents &= 0x8F;
-  this->write_bytes(CONFIG, &config_contents, 1);
-
-  // Set temperature resolution to 14bit
-  this->read_register(CONFIG, &config_contents, 1);
-  config_contents &= 0x3F;
-  this->write_bytes(CONFIG, &config_contents, 1);
-
-  // Set humidity resolution to 14bit
-  this->read_register(CONFIG, &config_contents, 1);
-  config_contents &= 0xCF;
-  this->write_bytes(CONFIG, &config_contents, 1);
+  // Set auto measurement rate to manual (on-demand via MEAS_TRIG)
+  this->read_register(REG_RESET_DRDY_INT_CONF, &config_contents, 1);
+  config_contents &= ~AMM_MASK;
+  this->write_bytes(REG_RESET_DRDY_INT_CONF, &config_contents, 1);
 }
 
 void HDC2010Component::dump_config() {
@@ -67,9 +53,9 @@ void HDC2010Component::dump_config() {
 void HDC2010Component::update() {
   // Trigger measurement
   uint8_t config_contents;
-  this->read_register(CONFIG, &config_contents, 1);
-  config_contents |= 0x01;
-  this->write_bytes(MEASUREMENT_CONFIG, &config_contents, 1);
+  this->read_register(REG_MEASUREMENT_CONF, &config_contents, 1);
+  config_contents |= MEAS_TRIG;
+  this->write_bytes(REG_MEASUREMENT_CONF, &config_contents, 1);
 
   // 1ms delay after triggering the sample
   set_timeout(1, [this]() {
@@ -90,8 +76,8 @@ void HDC2010Component::update() {
 float HDC2010Component::read_temp() {
   uint8_t byte[2];
 
-  this->read_register(HDC2010_CMD_TEMPERATURE_LOW, &byte[0], 1);
-  this->read_register(HDC2010_CMD_TEMPERATURE_HIGH, &byte[1], 1);
+  this->read_register(REG_TEMPERATURE_LOW, &byte[0], 1);
+  this->read_register(REG_TEMPERATURE_HIGH, &byte[1], 1);
 
   uint16_t temp = encode_uint16(byte[1], byte[0]);
   return (float) temp * 0.0025177f - 40.0f;
@@ -100,8 +86,8 @@ float HDC2010Component::read_temp() {
 float HDC2010Component::read_humidity() {
   uint8_t byte[2];
 
-  this->read_register(HDC2010_CMD_HUMIDITY_LOW, &byte[0], 1);
-  this->read_register(HDC2010_CMD_HUMIDITY_HIGH, &byte[1], 1);
+  this->read_register(REG_HUMIDITY_LOW, &byte[0], 1);
+  this->read_register(REG_HUMIDITY_HIGH, &byte[1], 1);
 
   uint16_t humidity = encode_uint16(byte[1], byte[0]);
   return (float) humidity * 0.001525879f;

esphome/components/mqtt/mqtt_backend_esp32.cpp

@@ -84,7 +84,7 @@ void MQTTBackendESP32::loop() {
   // handle only 1 message per loop iteration
   Event *event = this->mqtt_event_queue_.pop();
   if (event != nullptr) {
-    mqtt_event_handler_(*event);
+    this->mqtt_event_handler_(*event);
     this->mqtt_event_pool_.release(event);
   }
 

esphome/components/sensor/__init__.py

@@ -406,7 +406,9 @@ QUANTILE_SCHEMA = cv.All(
             cv.Optional(CONF_WINDOW_SIZE, default=5): cv.int_range(min=1, max=65535),
             cv.Optional(CONF_SEND_EVERY, default=5): cv.int_range(min=1, max=65535),
             cv.Optional(CONF_SEND_FIRST_AT, default=1): cv.int_range(min=1, max=65535),
-            cv.Optional(CONF_QUANTILE, default=0.9): cv.zero_to_one_float,
+            cv.Optional(CONF_QUANTILE, default=0.9): cv.float_range(
+                min=0, min_included=False, max=1
+            ),
         }
     ),
     validate_send_first_at,

esphome/components/usb_cdc_acm/usb_cdc_acm.cpp

@@ -26,16 +26,13 @@ void USBCDCACMInstance::queue_line_state_event(bool dtr, bool rts) {
   event->data.line_state.dtr = dtr;
   event->data.line_state.rts = rts;
 
-  if (!this->event_queue_.push(event)) {
-    ESP_LOGW(TAG, "Event queue full, line state event dropped (itf=%d)", this->itf_);
-    // Return event to pool since we couldn't queue it
-    this->event_pool_.release(event);
-  } else {
-    // Wake main loop immediately to process event
+  // Push always succeeds: pool is sized to queue capacity (SIZE-1), so if
+  // allocate() returned non-null, the queue cannot be full.
+  this->event_queue_.push(event);
+
 #if defined(USE_SOCKET_SELECT_SUPPORT) && defined(USE_WAKE_LOOP_THREADSAFE)
-    App.wake_loop_threadsafe();
+  App.wake_loop_threadsafe();
 #endif
-  }
 }
 
 void USBCDCACMInstance::queue_line_coding_event(uint32_t bit_rate, uint8_t stop_bits, uint8_t parity,
@@ -53,16 +50,13 @@ void USBCDCACMInstance::queue_line_coding_event(uint32_t bit_rate, uint8_t stop_
   event->data.line_coding.parity = parity;
   event->data.line_coding.data_bits = data_bits;
 
-  if (!this->event_queue_.push(event)) {
-    ESP_LOGW(TAG, "Event queue full, line coding event dropped (itf=%d)", this->itf_);
-    // Return event to pool since we couldn't queue it
-    this->event_pool_.release(event);
-  } else {
-    // Wake main loop immediately to process event
+  // Push always succeeds: pool is sized to queue capacity (SIZE-1), so if
+  // allocate() returned non-null, the queue cannot be full.
+  this->event_queue_.push(event);
+
 #if defined(USE_SOCKET_SELECT_SUPPORT) && defined(USE_WAKE_LOOP_THREADSAFE)
-    App.wake_loop_threadsafe();
+  App.wake_loop_threadsafe();
 #endif
-  }
 }
 
 void USBCDCACMInstance::process_events_() {

esphome/components/usb_cdc_acm/usb_cdc_acm.h

@@ -102,7 +102,11 @@ class USBCDCACMInstance : public uart::UARTComponent, public Parented<USBCDCACMC
   LineStateCallback line_state_callback_{nullptr};
 
   // Lock-free queue and event pool for cross-task event passing
-  EventPool<CDCEvent, EVENT_QUEUE_SIZE> event_pool_;
+  // Pool sized to queue capacity (SIZE-1) because LockFreeQueue<T,N> is a ring
+  // buffer that holds N-1 elements. This guarantees allocate() returns nullptr
+  // before push() can fail, preventing both a pool slot leak and an SPSC
+  // violation on the pool's internal free list.
+  EventPool<CDCEvent, EVENT_QUEUE_SIZE - 1> event_pool_;
   LockFreeQueue<CDCEvent, EVENT_QUEUE_SIZE> event_queue_;
 };
 

esphome/components/usb_host/usb_host.h

@@ -144,7 +144,10 @@ class USBClient : public Component {
   // Lock-free event queue and pool for USB task to main loop communication
   // Must be public for access from static callbacks
   LockFreeQueue<UsbEvent, USB_EVENT_QUEUE_SIZE> event_queue;
-  EventPool<UsbEvent, USB_EVENT_QUEUE_SIZE> event_pool;
+  // Pool sized to queue capacity (SIZE-1) because LockFreeQueue<T,N> is a ring
+  // buffer that holds N-1 elements. This guarantees allocate() returns nullptr
+  // before push() can fail, preventing a pool slot leak.
+  EventPool<UsbEvent, USB_EVENT_QUEUE_SIZE - 1> event_pool;
 
  protected:
   // Process USB events from the queue. Returns true if any work was done.

esphome/components/usb_host/usb_host_client.cpp

@@ -193,7 +193,8 @@ static void client_event_cb(const usb_host_client_event_msg_t *event_msg, void *
       return;
   }
 
-  // Push to lock-free queue (always succeeds since pool size == queue size)
+  // Push always succeeds: pool is sized to queue capacity (SIZE-1), so if
+  // allocate() returned non-null, the queue cannot be full.
   client->event_queue.push(event);
 
   // Re-enable component loop to process the queued event

esphome/components/usb_uart/usb_uart.cpp

@@ -160,11 +160,9 @@ void USBUartChannel::write_array(const uint8_t *data, size_t len) {
     size_t chunk_len = std::min(len, UsbOutputChunk::MAX_CHUNK_SIZE);
     memcpy(chunk->data, data, chunk_len);
     chunk->length = static_cast<uint8_t>(chunk_len);
-    if (!this->output_queue_.push(chunk)) {
-      this->output_pool_.release(chunk);
-      ESP_LOGE(TAG, "Output queue full - lost %zu bytes", len);
-      break;
-    }
+    // Push always succeeds: pool is sized to queue capacity (SIZE-1), so if
+    // allocate() returned non-null, the queue cannot be full.
+    this->output_queue_.push(chunk);
     data += chunk_len;
     len -= chunk_len;
   }
@@ -320,7 +318,8 @@ void USBUartComponent::start_input(USBUartChannel *channel) {
       chunk->channel = channel;
 
       // Push to lock-free queue for main loop processing
-      // Push always succeeds because pool size == queue size
+      // Push always succeeds: pool is sized to queue capacity (SIZE-1), so if
+      // allocate() returned non-null, the queue cannot be full.
       this->usb_data_queue_.push(chunk);
 
       // Re-enable component loop to process the queued data

esphome/components/usb_uart/usb_uart.h

@@ -158,7 +158,10 @@ class USBUartChannel : public uart::UARTComponent, public Parented<USBUartCompon
   // Larger structures first (8+ bytes)
   RingBuffer input_buffer_;
   LockFreeQueue<UsbOutputChunk, USB_OUTPUT_CHUNK_COUNT> output_queue_;
-  EventPool<UsbOutputChunk, USB_OUTPUT_CHUNK_COUNT> output_pool_;
+  // Pool sized to queue capacity (SIZE-1) because LockFreeQueue<T,N> is a ring
+  // buffer that holds N-1 elements. This guarantees allocate() returns nullptr
+  // before push() can fail, preventing a pool slot leak.
+  EventPool<UsbOutputChunk, USB_OUTPUT_CHUNK_COUNT - 1> output_pool_;
   std::function<void()> rx_callback_{};
   CdcEps cdc_dev_{};
   StringRef debug_prefix_{};
@@ -190,7 +193,8 @@ class USBUartComponent : public usb_host::USBClient {
   // Lock-free data transfer from USB task to main loop
   static constexpr int USB_DATA_QUEUE_SIZE = 32;
   LockFreeQueue<UsbDataChunk, USB_DATA_QUEUE_SIZE> usb_data_queue_;
-  EventPool<UsbDataChunk, USB_DATA_QUEUE_SIZE> chunk_pool_;
+  // Pool sized to queue capacity (SIZE-1) — see USBUartChannel::output_pool_ comment.
+  EventPool<UsbDataChunk, USB_DATA_QUEUE_SIZE - 1> chunk_pool_;
 
  protected:
   std::vector<USBUartChannel *> channels_{};

esphome/core/__init__.py

@@ -615,10 +615,6 @@ class EsphomeCore:
         self.address_cache: AddressCache | None = None
         # Cached config hash (computed lazily)
         self._config_hash: int | None = None
-        # True if compiling for C++ unit tests
-        self.cpp_testing = False
-        # Allowlist of components whose to_code should run during C++ testing
-        self.cpp_testing_codegen: set[str] = set()
 
     def reset(self):
         from esphome.pins import PIN_SCHEMA_REGISTRY
@@ -648,8 +644,6 @@ class EsphomeCore:
         self.current_component = None
         self.address_cache = None
         self._config_hash = None
-        self.cpp_testing = False
-        self.cpp_testing_codegen = set()
         PIN_SCHEMA_REGISTRY.reset()
 
     @contextmanager

esphome/loader.py

@@ -71,11 +71,6 @@ class ComponentManifest:
 
     @property
     def to_code(self) -> Callable[[Any], None] | None:
-        if CORE.cpp_testing:
-            # During C++ testing, only run to_code for allowlisted components
-            name = self.module.__package__.rsplit(".", 1)[-1]
-            if name not in CORE.cpp_testing_codegen:
-                return None
         return getattr(self.module, "to_code", None)
 
     @property
@@ -243,3 +238,13 @@ def get_platform(domain: str, platform: str) -> ComponentManifest | None:
 _COMPONENT_CACHE: dict[str, ComponentManifest] = {}
 CORE_COMPONENTS_PATH = (Path(__file__).parent / "components").resolve()
 _COMPONENT_CACHE["esphome"] = ComponentManifest(esphome.core.config)
+
+
+def _replace_component_manifest(domain: str, manifest: ComponentManifest) -> None:
+    """Replace the cached manifest for a component.
+
+    This is an intentionally-supported hook for the C++ test infrastructure
+    to install ``ComponentManifestOverride`` wrappers.  Normal application
+    code should never call this.
+    """
+    _COMPONENT_CACHE[domain] = manifest

script/build_helpers.py

@@ -2,21 +2,29 @@
 
 from __future__ import annotations
 
+from collections.abc import Callable
 import hashlib
+import importlib.util
 import os
 from pathlib import Path
 import subprocess
 import sys
 
-from helpers import get_all_dependencies
+from helpers import get_all_dependencies, root_path as _root_path
 import yaml
 
+# Ensure the repo root is on sys.path so that ``tests.testing_helpers`` and
+# override ``__init__.py`` modules can ``from tests.testing_helpers import ...``.
+if _root_path not in sys.path:
+    sys.path.insert(0, _root_path)
+
 from esphome.__main__ import command_compile, parse_args
 from esphome.config import validate_config
 from esphome.const import CONF_PLATFORM
 from esphome.core import CORE
-from esphome.loader import get_component
+from esphome.loader import get_component, get_platform
 from esphome.platformio_api import get_idedata
+from tests.testing_helpers import ComponentManifestOverride, set_testing_manifest
 
 # This must coincide with the version in /platformio.ini
 PLATFORMIO_GOOGLE_TEST_LIB = "google/googletest@^1.15.2"
@@ -32,19 +40,6 @@ ESPHOME_KEY = "esphome"
 HOST_KEY = "host"
 LOGGER_KEY = "logger"
 
-# Base config keys that are always present and must not be fully overridden
-# by component benchmark.yaml files. esphome: allows sub-key merging.
-BASE_CONFIG_KEYS = frozenset({ESPHOME_KEY, HOST_KEY, LOGGER_KEY})
-
-# Shared build flag — enables timezone code paths for testing/benchmarking.
-USE_TIME_TIMEZONE_FLAG = "-DUSE_TIME_TIMEZONE"
-
-# Components whose to_code should always run during C++ test/benchmark builds.
-# These are the minimal infrastructure components needed for host compilation.
-# Note: "core" is the esphome core config module (esphome/core/config.py),
-# which registers under package name "core" not "esphome".
-BASE_CODEGEN_COMPONENTS = {"core", "host", "logger"}
-
 # Exit codes
 EXIT_OK = 0
 EXIT_SKIPPED = 1
@@ -110,6 +105,8 @@ def get_platform_components(components: list[str], tests_dir: Path) -> list[str]
             if not domain_dir.is_dir():
                 continue
             domain = domain_dir.name
+            if domain.startswith("__"):
+                continue
             domain_module = get_component(domain)
             if domain_module is None or not domain_module.is_platform_component:
                 raise ValueError(
@@ -130,7 +127,8 @@ def load_component_yaml_configs(components: list[str], tests_dir: Path) -> dict:
 
     The ``esphome:`` key is special: its sub-keys are merged into the
     existing esphome config (e.g. to add ``areas:`` or ``devices:``).
-    Other base config keys (``host:``, ``logger:``) are not overridable.
+    Keys already present in the base config (e.g. ``host:``, ``logger:``)
+    are protected by ``setdefault`` in the caller.
 
     Args:
         components: List of component directory names
@@ -139,11 +137,6 @@ def load_component_yaml_configs(components: list[str], tests_dir: Path) -> dict:
     Returns:
         Merged dict of component configs to add to the base config
     """
-    # Note: components are processed in sorted order. For conflicting keys
-    # (e.g. two benchmark.yaml files both declaring sensor:), the first
-    # component alphabetically wins via setdefault(). This is fine for now
-    # with a single benchmark component (api) but would need a real merge
-    # strategy if multiple components declare overlapping configs.
     merged: dict = {}
     for component in components:
         yaml_path = tests_dir / component / BENCHMARK_YAML_FILENAME
@@ -153,9 +146,6 @@ def load_component_yaml_configs(components: list[str], tests_dir: Path) -> dict:
             component_config = yaml.safe_load(f)
         if component_config and isinstance(component_config, dict):
             for key, value in component_config.items():
-                if key in BASE_CONFIG_KEYS - {ESPHOME_KEY}:
-                    # host: and logger: are not overridable
-                    continue
                 if key == ESPHOME_KEY and isinstance(value, dict):
                     # Merge esphome sub-keys rather than replacing
                     esphome_extra = merged.setdefault(ESPHOME_KEY, {})
@@ -198,11 +188,78 @@ def create_host_config(
     }
 
 
+def _wrap_manifest(
+    comp_name: str,
+) -> ComponentManifestOverride | None:
+    """Wrap a component manifest in a ComponentManifestOverride with to_code suppressed.
+
+    If the manifest is already wrapped or not found, returns None.
+    Otherwise returns the newly created override after installing it.
+    """
+    if "." in comp_name:
+        domain, component = comp_name.split(".", maxsplit=1)
+        manifest = get_platform(domain, component)
+        cache_key = f"{component}.{domain}"
+    else:
+        manifest = get_component(comp_name)
+        cache_key = comp_name
+
+    if manifest is None or isinstance(manifest, ComponentManifestOverride):
+        return None
+
+    override = ComponentManifestOverride(manifest)
+    override.to_code = None  # suppress by default
+    set_testing_manifest(cache_key, override)
+    return override
+
+
+def load_test_manifest_overrides(
+    components: list[str],
+    tests_dir: Path,
+) -> None:
+    """Apply per-component manifest overrides from test ``__init__.py`` files.
+
+    For every component, wraps its manifest and suppresses ``to_code``.
+    If the component's test directory contains an ``__init__.py`` that
+    defines ``override_manifest(manifest)``, it is called to customise
+    the override (e.g. ``manifest.enable_codegen()``).
+    """
+    for comp_name in components:
+        override = _wrap_manifest(comp_name)
+        if override is None:
+            continue
+
+        if "." in comp_name:
+            domain, component = comp_name.split(".", maxsplit=1)
+            cache_key = f"{component}.{domain}"
+            test_init = tests_dir / component / domain / "__init__.py"
+        else:
+            cache_key = comp_name
+            test_init = tests_dir / comp_name / "__init__.py"
+
+        if not test_init.is_file():
+            continue
+        spec = importlib.util.spec_from_file_location(
+            f"_test_manifest_override.{cache_key}", test_init
+        )
+        if spec is None or spec.loader is None:
+            continue
+        mod = importlib.util.module_from_spec(spec)
+        spec.loader.exec_module(mod)
+        override_fn = getattr(mod, "override_manifest", None)
+        if override_fn is not None:
+            override_fn(override)
+
+
+# Type alias for manifest override loaders
+ManifestOverrideLoader = Callable[[list[str]], None]
+
+
 def compile_and_get_binary(
     config: dict,
     components: list[str],
-    codegen_components: set[str],
     tests_dir: Path,
+    manifest_override_loader: ManifestOverrideLoader,
     label: str = "build",
 ) -> tuple[int, str | None]:
     """Compile an ESPHome configuration and return the binary path.
@@ -210,8 +267,8 @@ def compile_and_get_binary(
     Args:
         config: ESPHome configuration dict (already created via create_host_config)
         components: List of components to include in the build
-        codegen_components: Set of component names whose to_code should run
         tests_dir: Base directory for test files (used as config_path base)
+        manifest_override_loader: Callback to apply manifest overrides for components
         label: Label for log messages (e.g. "unit tests", "benchmarks")
 
     Returns:
@@ -238,18 +295,21 @@ def compile_and_get_binary(
         else:
             config.setdefault(key, value)
 
+    # Apply manifest overrides before dependency resolution so that any
+    # dependency additions made by override_manifest() are picked up.
+    manifest_override_loader(components)
+
     # Obtain possible dependencies BEFORE validate_config, because
     # get_all_dependencies calls CORE.reset() which clears build_path.
-    # Always include 'time' because USE_TIME_TIMEZONE is defined as a build flag,
-    # which causes core/time.h to include components/time/posix_tz.h.
     components_with_dependencies: list[str] = sorted(
-        get_all_dependencies(set(components) | {"time"}, cpp_testing=True)
+        get_all_dependencies(set(components))
     )
 
+    # Apply overrides for any transitively discovered dependencies.
+    manifest_override_loader(components_with_dependencies)
+
     CORE.config_path = tests_dir / "dummy.yaml"
     CORE.dashboard = None
-    CORE.cpp_testing = True
-    CORE.cpp_testing_codegen = codegen_components
 
     # Validate config will expand the above with defaults:
     config = validate_config(config, {})
@@ -305,7 +365,7 @@ def compile_and_get_binary(
 def build_and_run(
     selected_components: list[str],
     tests_dir: Path,
-    codegen_components: set[str],
+    manifest_override_loader: ManifestOverrideLoader,
     config_prefix: str,
     friendly_name: str,
     libraries: str | list[str],
@@ -324,7 +384,7 @@ def build_and_run(
     Args:
         selected_components: Components to include (directory names in tests_dir)
         tests_dir: Directory containing test/benchmark files
-        codegen_components: Components whose to_code should run
+        manifest_override_loader: Callback to apply manifest overrides for components
         config_prefix: Prefix for the config name (e.g. "cpptests", "cppbench")
         friendly_name: Human-readable name for the config
         libraries: PlatformIO library specification(s)
@@ -382,7 +442,7 @@ def build_and_run(
     )
 
     exit_code, program_path = compile_and_get_binary(
-        config, components, codegen_components, tests_dir, label
+        config, components, tests_dir, manifest_override_loader, label
     )
 
     if exit_code != EXIT_OK or program_path is None:

script/cpp_benchmark.py

@@ -2,18 +2,18 @@
 """Build and run C++ benchmarks for ESPHome components using Google Benchmark."""
 
 import argparse
+from functools import partial
 import json
 import os
 from pathlib import Path
 import sys
 
-from helpers import root_path
-from test_helpers import (
-    BASE_CODEGEN_COMPONENTS,
+from build_helpers import (
     PLATFORMIO_GOOGLE_BENCHMARK_LIB,
-    USE_TIME_TIMEZONE_FLAG,
     build_and_run,
+    load_test_manifest_overrides,
 )
+from helpers import root_path
 
 # Path to /tests/benchmarks/components
 BENCHMARKS_DIR: Path = Path(root_path) / "tests" / "benchmarks" / "components"
@@ -21,11 +21,6 @@ BENCHMARKS_DIR: Path = Path(root_path) / "tests" / "benchmarks" / "components"
 # Path to /tests/benchmarks/core (always included, not a component)
 CORE_BENCHMARKS_DIR: Path = Path(root_path) / "tests" / "benchmarks" / "core"
 
-# Additional codegen components beyond the base set.
-# json is needed because its to_code adds the ArduinoJson library
-# (auto-loaded by api, but cpp_testing suppresses to_code unless listed).
-BENCHMARK_CODEGEN_COMPONENTS = BASE_CODEGEN_COMPONENTS | {"json"}
-
 PLATFORMIO_OPTIONS = {
     "build_unflags": [
         "-Os",  # remove default size-opt
@@ -33,7 +28,6 @@ PLATFORMIO_OPTIONS = {
     "build_flags": [
         "-O2",  # optimize for speed (CodSpeed recommends RelWithDebInfo)
         "-g",  # debug symbols for profiling
-        USE_TIME_TIMEZONE_FLAG,
         "-DUSE_BENCHMARK",  # disable WarnIfComponentBlockingGuard in finish()
     ],
     # Use deep+ LDF mode to ensure PlatformIO detects the benchmark
@@ -73,7 +67,9 @@ def run_benchmarks(selected_components: list[str], build_only: bool = False) ->
     return build_and_run(
         selected_components=selected_components,
         tests_dir=BENCHMARKS_DIR,
-        codegen_components=BENCHMARK_CODEGEN_COMPONENTS,
+        manifest_override_loader=partial(
+            load_test_manifest_overrides, tests_dir=BENCHMARKS_DIR
+        ),
         config_prefix="cppbench",
         friendly_name="CPP Benchmarks",
         libraries=benchmark_lib,

script/cpp_unit_test.py

@@ -1,15 +1,15 @@
 #!/usr/bin/env python3
 import argparse
+from functools import partial
 from pathlib import Path
 import sys
 
-from helpers import get_all_components, root_path
-from test_helpers import (
-    BASE_CODEGEN_COMPONENTS,
+from build_helpers import (
     PLATFORMIO_GOOGLE_TEST_LIB,
-    USE_TIME_TIMEZONE_FLAG,
     build_and_run,
+    load_test_manifest_overrides,
 )
+from helpers import get_all_components, root_path
 
 # Path to /tests/components
 COMPONENTS_TESTS_DIR: Path = Path(root_path) / "tests" / "components"
@@ -21,7 +21,6 @@ PLATFORMIO_OPTIONS = {
     ],
     "build_flags": [
         "-Og",  # optimize for debug
-        USE_TIME_TIMEZONE_FLAG,
         "-DESPHOME_DEBUG",  # enable debug assertions
         # Enable the address and undefined behavior sanitizers
         "-fsanitize=address",
@@ -39,7 +38,9 @@ def run_tests(selected_components: list[str]) -> int:
     return build_and_run(
         selected_components=selected_components,
         tests_dir=COMPONENTS_TESTS_DIR,
-        codegen_components=BASE_CODEGEN_COMPONENTS,
+        manifest_override_loader=partial(
+            load_test_manifest_overrides, tests_dir=COMPONENTS_TESTS_DIR
+        ),
         config_prefix="cpptests",
         friendly_name="CPP Unit Tests",
         libraries=PLATFORMIO_GOOGLE_TEST_LIB,

script/determine-jobs.py

@@ -388,7 +388,7 @@ BENCHMARKS_COMPONENTS_PATH = "tests/benchmarks/components"
 BENCHMARK_INFRASTRUCTURE_FILES = frozenset(
     {
         "script/cpp_benchmark.py",
-        "script/test_helpers.py",
+        "script/build_helpers.py",
         "script/setup_codspeed_lib.py",
     }
 )
@@ -402,7 +402,7 @@ def should_run_benchmarks(branch: str | None = None) -> bool:
     1. Core C++ files changed (esphome/core/*)
     2. A directly changed component has benchmark files (no dependency expansion)
     3. Benchmark infrastructure changed (tests/benchmarks/*, script/cpp_benchmark.py,
-       script/test_helpers.py, script/setup_codspeed_lib.py)
+       script/build_helpers.py, script/setup_codspeed_lib.py)
 
     Unlike unit tests, benchmarks do NOT expand to dependent components.
     Changing ``sensor`` does not trigger ``api`` benchmarks just because

script/helpers.py

@@ -627,14 +627,12 @@ def get_usable_cpu_count() -> int:
 
 
 def get_all_dependencies(
-    component_names: set[str], cpp_testing: bool = False
+    component_names: set[str],
 ) -> set[str]:
     """Get all dependencies for a set of components.
 
     Args:
         component_names: Set of component names to get dependencies for
-        cpp_testing: If True, set CORE.cpp_testing so AUTO_LOAD callables that
-                     conditionally include testing-only dependencies work correctly
 
     Returns:
         Set of all components including dependencies and auto-loaded components
@@ -652,7 +650,6 @@ def get_all_dependencies(
 
     # Reset CORE to ensure clean state
     CORE.reset()
-    CORE.cpp_testing = cpp_testing
 
     # Set up fake config path for component loading
     root = Path(__file__).parent.parent

tests/benchmarks/components/core/__init__.py

@@ -0,0 +1,7 @@
+from tests.testing_helpers import ComponentManifestOverride
+
+
+def override_manifest(manifest: ComponentManifestOverride) -> None:
+    # core (esphome/core/config.py) must run its to_code during builds
+    # because it bootstraps the fundamental application infrastructure.
+    manifest.enable_codegen()

tests/benchmarks/components/host/__init__.py

@@ -0,0 +1,7 @@
+from tests.testing_helpers import ComponentManifestOverride
+
+
+def override_manifest(manifest: ComponentManifestOverride) -> None:
+    # host must run its to_code during builds because it sets up
+    # the host platform target execution environment.
+    manifest.enable_codegen()

tests/benchmarks/components/json/__init__.py

@@ -0,0 +1,7 @@
+from tests.testing_helpers import ComponentManifestOverride
+
+
+def override_manifest(manifest: ComponentManifestOverride) -> None:
+    # json must run its to_code during benchmark builds because it
+    # adds the ArduinoJson library dependency needed by the API component.
+    manifest.enable_codegen()

tests/benchmarks/components/logger/__init__.py

@@ -0,0 +1,7 @@
+from tests.testing_helpers import ComponentManifestOverride
+
+
+def override_manifest(manifest: ComponentManifestOverride) -> None:
+    # logger must run its to_code during builds because it configures
+    # the logging subsystem used by ESP_LOG* macros.
+    manifest.enable_codegen()

tests/benchmarks/components/time/__init__.py

@@ -0,0 +1,9 @@
+import esphome.codegen as cg
+from tests.testing_helpers import ComponentManifestOverride
+
+
+def override_manifest(manifest: ComponentManifestOverride) -> None:
+    async def to_code(config):
+        cg.add_build_flag("-DUSE_TIME_TIMEZONE")
+
+    manifest.to_code = to_code

tests/components/README.md

@@ -14,11 +14,63 @@ include the relevant `.cpp` and `.h` test files there.
 
 ### Override component code generation for testing
 
-When generating code for testing, ESPHome won't invoke the component's `to_code` function, since most components do not
-need to generate configuration code for testing.
+During C++ test builds, `to_code` is suppressed for every component by default — most components do not
+need to generate configuration code for a unit test binary.
 
-If you do need to generate code to for example configure compilation flags or add libraries,
-add the component name to the `CPP_TESTING_CODEGEN_COMPONENTS` allowlist in `script/cpp_unit_test.py`.
+#### Manifest overrides
+
+If your component needs to customise code generation behavior for testing — for example to re-enable
+`to_code`, supply a lightweight stub, add a test-only dependency, or change any other manifest attribute —
+create an `__init__.py` in your component's test directory and define `override_manifest`:
+
+**Top-level component** (`tests/components/<component>/__init__.py`):
+
+```python
+from tests.testing_helpers import ComponentManifestOverride
+
+def override_manifest(manifest: ComponentManifestOverride) -> None:
+    # Re-enable the component's own to_code (needed when the component must
+    # emit C++ setup code that the test binary depends on at link time).
+    manifest.enable_codegen()
+```
+
+Or supply a lightweight stub instead of the real `to_code`:
+
+```python
+from tests.testing_helpers import ComponentManifestOverride
+
+def override_manifest(manifest: ComponentManifestOverride) -> None:
+    async def to_code_testing(config):
+        # Only emit what the C++ tests actually need
+        pass
+
+    manifest.to_code = to_code_testing
+    manifest.dependencies = manifest.dependencies + ["some_test_only_dep"]
+```
+
+**Platform component** (`tests/components/<component>/<domain>/__init__.py`,
+e.g. `tests/components/my_sensor/sensor/__init__.py`):
+
+```python
+from tests.testing_helpers import ComponentManifestOverride
+
+def override_manifest(manifest: ComponentManifestOverride) -> None:
+    manifest.enable_codegen()
+```
+
+`override_manifest` receives a `ComponentManifestOverride` that wraps the real manifest.
+Attribute assignments store an override; reads fall back to the real manifest when no
+override is present.
+
+Key methods:
+
+| Method | Effect |
+|---|---|
+| `manifest.enable_codegen()` | Remove the `to_code` suppression, re-enabling code generation |
+| `manifest.restore()` | Clear **all** overrides, reverting every attribute to the original |
+
+The function is called after `to_code` has already been set to `None`, so calling
+`enable_codegen()` is a deliberate opt-in.
 
 ## Running component unit tests
 

tests/components/core/__init__.py

@@ -0,0 +1,8 @@
+from tests.testing_helpers import ComponentManifestOverride
+
+
+def override_manifest(manifest: ComponentManifestOverride) -> None:
+    # core (esphome/core/config.py) must run its to_code during C++ test builds
+    # because it bootstraps the fundamental application infrastructure that all
+    # components depend on (component registration, event loop, etc.).
+    manifest.enable_codegen()

tests/components/host/__init__.py

@@ -0,0 +1,7 @@
+from tests.testing_helpers import ComponentManifestOverride
+
+
+def override_manifest(manifest: ComponentManifestOverride) -> None:
+    # host must run its to_code during C++ test builds because it sets up the
+    # host platform target, which is the execution environment for all unit tests.
+    manifest.enable_codegen()

tests/components/logger/__init__.py

@@ -0,0 +1,7 @@
+from tests.testing_helpers import ComponentManifestOverride
+
+
+def override_manifest(manifest: ComponentManifestOverride) -> None:
+    # logger must run its to_code during C++ test builds because it configures
+    # the logging subsystem used by ESP_LOG* macros throughout component code.
+    manifest.enable_codegen()

tests/components/time/__init__.py

@@ -0,0 +1,9 @@
+import esphome.codegen as cg
+from tests.testing_helpers import ComponentManifestOverride
+
+
+def override_manifest(manifest: ComponentManifestOverride) -> None:
+    async def to_code(config):
+        cg.add_build_flag("-DUSE_TIME_TIMEZONE")
+
+    manifest.to_code = to_code

tests/script/test_determine_jobs.py

@@ -1821,3 +1821,151 @@ def test_component_batching_beta_branch_40_per_batch(
         all_components.extend(batch_str.split())
     assert len(all_components) == 120
     assert set(all_components) == set(component_names)
+
+
+# --- should_run_benchmarks tests ---
+
+
+def test_should_run_benchmarks_core_change() -> None:
+    """Test benchmarks trigger on core C++ file changes."""
+    with patch.object(
+        determine_jobs, "changed_files", return_value=["esphome/core/scheduler.cpp"]
+    ):
+        assert determine_jobs.should_run_benchmarks() is True
+
+
+def test_should_run_benchmarks_core_header_change() -> None:
+    """Test benchmarks trigger on core header changes."""
+    with patch.object(
+        determine_jobs, "changed_files", return_value=["esphome/core/helpers.h"]
+    ):
+        assert determine_jobs.should_run_benchmarks() is True
+
+
+def test_should_run_benchmarks_benchmark_infra_change() -> None:
+    """Test benchmarks trigger on benchmark infrastructure changes."""
+    for infra_file in [
+        "script/cpp_benchmark.py",
+        "script/build_helpers.py",
+        "script/setup_codspeed_lib.py",
+    ]:
+        with patch.object(determine_jobs, "changed_files", return_value=[infra_file]):
+            assert determine_jobs.should_run_benchmarks() is True, (
+                f"Expected benchmarks to run for {infra_file}"
+            )
+
+
+def test_should_run_benchmarks_benchmark_file_change() -> None:
+    """Test benchmarks trigger on benchmark file changes."""
+    with patch.object(
+        determine_jobs,
+        "changed_files",
+        return_value=["tests/benchmarks/components/api/bench_proto_encode.cpp"],
+    ):
+        assert determine_jobs.should_run_benchmarks() is True
+
+
+def test_should_run_benchmarks_core_benchmark_file_change() -> None:
+    """Test benchmarks trigger on core benchmark file changes."""
+    with patch.object(
+        determine_jobs,
+        "changed_files",
+        return_value=["tests/benchmarks/core/bench_scheduler.cpp"],
+    ):
+        assert determine_jobs.should_run_benchmarks() is True
+
+
+def test_should_run_benchmarks_benchmarked_component_change(tmp_path: Path) -> None:
+    """Test benchmarks trigger when a benchmarked component changes."""
+    # Create a fake benchmarks directory with an 'api' component
+    benchmarks_dir = tmp_path / "tests" / "benchmarks" / "components" / "api"
+    benchmarks_dir.mkdir(parents=True)
+    (benchmarks_dir / "bench_proto_encode.cpp").write_text("// benchmark")
+
+    with (
+        patch.object(
+            determine_jobs,
+            "changed_files",
+            return_value=["esphome/components/api/proto.h"],
+        ),
+        patch.object(determine_jobs, "root_path", str(tmp_path)),
+        patch.object(
+            determine_jobs,
+            "BENCHMARKS_COMPONENTS_PATH",
+            "tests/benchmarks/components",
+        ),
+    ):
+        assert determine_jobs.should_run_benchmarks() is True
+
+
+def test_should_run_benchmarks_non_benchmarked_component_change(
+    tmp_path: Path,
+) -> None:
+    """Test benchmarks do NOT trigger for non-benchmarked component changes."""
+    # Create a fake benchmarks directory with only 'api'
+    benchmarks_dir = tmp_path / "tests" / "benchmarks" / "components" / "api"
+    benchmarks_dir.mkdir(parents=True)
+    (benchmarks_dir / "bench_proto_encode.cpp").write_text("// benchmark")
+
+    with (
+        patch.object(
+            determine_jobs,
+            "changed_files",
+            return_value=["esphome/components/sensor/__init__.py"],
+        ),
+        patch.object(determine_jobs, "root_path", str(tmp_path)),
+        patch.object(
+            determine_jobs,
+            "BENCHMARKS_COMPONENTS_PATH",
+            "tests/benchmarks/components",
+        ),
+    ):
+        assert determine_jobs.should_run_benchmarks() is False
+
+
+def test_should_run_benchmarks_no_dependency_expansion(tmp_path: Path) -> None:
+    """Test benchmarks do NOT expand to dependent components.
+
+    Changing 'sensor' should not trigger 'api' benchmarks even if api
+    depends on sensor. This is intentional — benchmark runs should be
+    targeted to directly changed components only.
+    """
+    benchmarks_dir = tmp_path / "tests" / "benchmarks" / "components" / "api"
+    benchmarks_dir.mkdir(parents=True)
+    (benchmarks_dir / "bench_proto_encode.cpp").write_text("// benchmark")
+
+    with (
+        patch.object(
+            determine_jobs,
+            "changed_files",
+            # sensor is a dependency of api, but benchmarks don't expand
+            return_value=["esphome/components/sensor/sensor.cpp"],
+        ),
+        patch.object(determine_jobs, "root_path", str(tmp_path)),
+        patch.object(
+            determine_jobs,
+            "BENCHMARKS_COMPONENTS_PATH",
+            "tests/benchmarks/components",
+        ),
+    ):
+        assert determine_jobs.should_run_benchmarks() is False
+
+
+def test_should_run_benchmarks_unrelated_change() -> None:
+    """Test benchmarks do NOT trigger for unrelated changes."""
+    with patch.object(determine_jobs, "changed_files", return_value=["README.md"]):
+        assert determine_jobs.should_run_benchmarks() is False
+
+
+def test_should_run_benchmarks_no_changes() -> None:
+    """Test benchmarks do NOT trigger with no changes."""
+    with patch.object(determine_jobs, "changed_files", return_value=[]):
+        assert determine_jobs.should_run_benchmarks() is False
+
+
+def test_should_run_benchmarks_with_branch() -> None:
+    """Test should_run_benchmarks passes branch to changed_files."""
+    with patch.object(determine_jobs, "changed_files") as mock_changed:
+        mock_changed.return_value = []
+        determine_jobs.should_run_benchmarks("release")
+        mock_changed.assert_called_with("release")

tests/script/test_helpers.py

@@ -1073,28 +1073,6 @@ def test_get_all_dependencies_platform_component_with_dependencies() -> None:
         assert result == {"sensor.bthome", "sensor"}
 
 
-def test_get_all_dependencies_cpp_testing_flag() -> None:
-    """cpp_testing=True propagates to CORE.cpp_testing during resolution."""
-    from esphome.core import CORE
-
-    with (
-        patch("esphome.loader.get_component") as mock_get_component,
-        patch("esphome.loader.get_platform"),
-    ):
-        observed: list[bool] = []
-
-        def capturing_get_component(name: str):
-            observed.append(CORE.cpp_testing)
-
-        mock_get_component.side_effect = capturing_get_component
-
-        helpers.get_all_dependencies({"some_comp"}, cpp_testing=True)
-
-    assert observed and all(observed), (
-        "CORE.cpp_testing should be True during resolution"
-    )
-
-
 def test_get_components_from_integration_fixtures() -> None:
     """Test extraction of components from fixture YAML files."""
     yaml_content = {

tests/script/test_test_helpers.py

@@ -0,0 +1,260 @@
+"""Unit tests for script/build_helpers.py manifest override and build helpers."""
+
+import os
+from pathlib import Path
+import sys
+import textwrap
+from unittest.mock import MagicMock, patch
+
+import pytest
+
+# Add the script directory to Python path so we can import build_helpers
+sys.path.insert(
+    0, os.path.abspath(os.path.join(os.path.dirname(__file__), "..", "..", "script"))
+)
+
+import build_helpers  # noqa: E402
+
+from esphome.loader import ComponentManifest  # noqa: E402
+from tests.testing_helpers import ComponentManifestOverride  # noqa: E402
+
+# ---------------------------------------------------------------------------
+# Helpers
+# ---------------------------------------------------------------------------
+
+
+def _make_component_manifest(*, to_code=None, dependencies=None) -> ComponentManifest:
+    mod = MagicMock()
+    mod.to_code = to_code
+    mod.DEPENDENCIES = dependencies or []
+    return ComponentManifest(mod)
+
+
+# ---------------------------------------------------------------------------
+# filter_components_with_files
+# ---------------------------------------------------------------------------
+
+
+def test_filter_keeps_components_with_cpp_files(tmp_path: Path) -> None:
+    comp_dir = tmp_path / "mycomp"
+    comp_dir.mkdir()
+    (comp_dir / "mycomp_test.cpp").write_text("")
+
+    result = build_helpers.filter_components_with_files(["mycomp"], tmp_path)
+
+    assert result == ["mycomp"]
+
+
+def test_filter_keeps_components_with_h_files(tmp_path: Path) -> None:
+    comp_dir = tmp_path / "mycomp"
+    comp_dir.mkdir()
+    (comp_dir / "helpers.h").write_text("")
+
+    result = build_helpers.filter_components_with_files(["mycomp"], tmp_path)
+
+    assert result == ["mycomp"]
+
+
+def test_filter_drops_components_without_test_dir(tmp_path: Path) -> None:
+    result = build_helpers.filter_components_with_files(["nodir"], tmp_path)
+
+    assert result == []
+
+
+def test_filter_drops_components_with_no_cpp_or_h(tmp_path: Path) -> None:
+    comp_dir = tmp_path / "mycomp"
+    comp_dir.mkdir()
+    (comp_dir / "README.md").write_text("")
+
+    result = build_helpers.filter_components_with_files(["mycomp"], tmp_path)
+
+    assert result == []
+
+
+# ---------------------------------------------------------------------------
+# get_platform_components
+# ---------------------------------------------------------------------------
+
+
+def test_get_platform_components_discovers_subdirectory(tmp_path: Path) -> None:
+    (tmp_path / "bthome" / "sensor").mkdir(parents=True)
+
+    sensor_mod = MagicMock()
+    sensor_mod.IS_PLATFORM_COMPONENT = True
+
+    with patch(
+        "build_helpers.get_component", return_value=ComponentManifest(sensor_mod)
+    ):
+        result = build_helpers.get_platform_components(["bthome"], tmp_path)
+
+    assert result == ["sensor.bthome"]
+
+
+def test_get_platform_components_skips_pycache(tmp_path: Path) -> None:
+    (tmp_path / "bthome" / "__pycache__").mkdir(parents=True)
+
+    result = build_helpers.get_platform_components(["bthome"], tmp_path)
+
+    assert result == []
+
+
+def test_get_platform_components_raises_for_invalid_domain(tmp_path: Path) -> None:
+    (tmp_path / "bthome" / "notadomain").mkdir(parents=True)
+
+    with (
+        patch("build_helpers.get_component", return_value=None),
+        pytest.raises(ValueError, match="notadomain"),
+    ):
+        build_helpers.get_platform_components(["bthome"], tmp_path)
+
+
+# ---------------------------------------------------------------------------
+# load_test_manifest_overrides
+# ---------------------------------------------------------------------------
+
+
+def test_load_suppresses_to_code(tmp_path: Path) -> None:
+    """to_code is always set to None before the override is called."""
+
+    async def real_to_code(config):
+        pass
+
+    inner = _make_component_manifest(to_code=real_to_code)
+
+    with (
+        patch("build_helpers.get_component", return_value=inner),
+        patch("build_helpers.set_testing_manifest") as mock_set,
+    ):
+        build_helpers.load_test_manifest_overrides(["mycomp"], tmp_path)
+        installed: ComponentManifestOverride = mock_set.call_args[0][1]
+
+    assert installed.to_code is None
+
+
+def test_load_calls_override_fn(tmp_path: Path) -> None:
+    """override_manifest() in test_init is called with the ComponentManifestOverride."""
+    comp_dir = tmp_path / "mycomp"
+    comp_dir.mkdir()
+    init_py = comp_dir / "__init__.py"
+    init_py.write_text(
+        textwrap.dedent("""\
+        def override_manifest(manifest):
+            manifest.dependencies = ["injected"]
+    """)
+    )
+
+    inner = _make_component_manifest()
+    override = ComponentManifestOverride(inner)
+    override.to_code = None
+
+    with (
+        patch("build_helpers.get_component", return_value=inner),
+        patch("build_helpers.set_testing_manifest") as mock_set,
+    ):
+        build_helpers.load_test_manifest_overrides(["mycomp"], tmp_path)
+        installed: ComponentManifestOverride = mock_set.call_args[0][1]
+
+    assert installed.dependencies == ["injected"]
+
+
+def test_load_enable_codegen_in_override(tmp_path: Path) -> None:
+    """An override_manifest that calls enable_codegen() restores to_code."""
+
+    async def real_to_code(config):
+        pass
+
+    comp_dir = tmp_path / "mycomp"
+    comp_dir.mkdir()
+    init_py = comp_dir / "__init__.py"
+    init_py.write_text(
+        textwrap.dedent("""\
+        def override_manifest(manifest):
+            manifest.enable_codegen()
+    """)
+    )
+
+    inner = _make_component_manifest(to_code=real_to_code)
+
+    with (
+        patch("build_helpers.get_component", return_value=inner),
+        patch("build_helpers.set_testing_manifest") as mock_set,
+    ):
+        build_helpers.load_test_manifest_overrides(["mycomp"], tmp_path)
+        installed: ComponentManifestOverride = mock_set.call_args[0][1]
+
+    assert installed.to_code is real_to_code
+
+
+def test_load_no_override_file(tmp_path: Path) -> None:
+    """No override file: manifest is wrapped and to_code suppressed, nothing else."""
+    inner = _make_component_manifest()
+
+    with (
+        patch("build_helpers.get_component", return_value=inner),
+        patch("build_helpers.set_testing_manifest") as mock_set,
+    ):
+        build_helpers.load_test_manifest_overrides(["mycomp"], tmp_path)
+
+    mock_set.assert_called_once()
+    key, installed = mock_set.call_args[0]
+    assert key == "mycomp"
+    assert isinstance(installed, ComponentManifestOverride)
+
+
+def test_load_skips_already_wrapped(tmp_path: Path) -> None:
+    """Components already wrapped as ComponentManifestOverride are not double-wrapped."""
+    inner = _make_component_manifest()
+    already_wrapped = ComponentManifestOverride(inner)
+
+    with (
+        patch("build_helpers.get_component", return_value=already_wrapped),
+        patch("build_helpers.set_testing_manifest") as mock_set,
+    ):
+        build_helpers.load_test_manifest_overrides(["mycomp"], tmp_path)
+
+    mock_set.assert_not_called()
+
+
+def test_load_skips_platform_component_already_wrapped(tmp_path: Path) -> None:
+    inner = _make_component_manifest()
+    already_wrapped = ComponentManifestOverride(inner)
+
+    with (
+        patch("build_helpers.get_platform", return_value=already_wrapped),
+        patch("build_helpers.set_testing_manifest") as mock_set,
+    ):
+        build_helpers.load_test_manifest_overrides(["sensor.bthome"], tmp_path)
+
+    mock_set.assert_not_called()
+
+
+def test_load_wraps_top_level_component(tmp_path: Path) -> None:
+    inner = _make_component_manifest()
+
+    with (
+        patch("build_helpers.get_component", return_value=inner),
+        patch("build_helpers.set_testing_manifest") as mock_set,
+    ):
+        build_helpers.load_test_manifest_overrides(["mycomp"], tmp_path)
+
+    mock_set.assert_called_once()
+    key, installed = mock_set.call_args[0]
+    assert key == "mycomp"
+    assert isinstance(installed, ComponentManifestOverride)
+    assert installed.to_code is None
+
+
+def test_load_wraps_platform_component(tmp_path: Path) -> None:
+    inner = _make_component_manifest()
+
+    with (
+        patch("build_helpers.get_platform", return_value=inner),
+        patch("build_helpers.set_testing_manifest") as mock_set,
+    ):
+        build_helpers.load_test_manifest_overrides(["sensor.bthome"], tmp_path)
+
+    mock_set.assert_called_once()
+    key, installed = mock_set.call_args[0]
+    assert key == "bthome.sensor"
+    assert isinstance(installed, ComponentManifestOverride)
+    assert installed.to_code is None

tests/testing_helpers.py

@@ -0,0 +1,63 @@
+from typing import Any
+
+from esphome.loader import ComponentManifest, _replace_component_manifest
+
+
+class ComponentManifestOverride:
+    """Mutable wrapper around ComponentManifest for test-specific attribute overrides.
+
+    When ``tests/components/<name>/__init__.py`` defines::
+
+        def override_manifest(manifest: ComponentManifestOverride) -> None:
+            ...
+
+    the function receives an instance of this class wrapping the real component
+    manifest.  Any attribute assignment stores an override; reads fall back to
+    the underlying ``ComponentManifest`` when no override has been set.
+
+    Example::
+
+        def override_manifest(manifest: ComponentManifestOverride) -> None:
+            async def to_code_testing(config):
+                pass  # lightweight no-op stub for C++ unit tests
+
+            manifest.to_code = to_code_testing
+            manifest.dependencies = manifest.dependencies + ["extra_dep_for_tests"]
+    """
+
+    def __init__(self, wrapped: "ComponentManifest") -> None:
+        object.__setattr__(self, "_wrapped", wrapped)
+        object.__setattr__(self, "_overrides", {})
+
+    def __getattr__(self, name: str) -> Any:
+        overrides: dict[str, Any] = object.__getattribute__(self, "_overrides")
+        if name in overrides:
+            return overrides[name]
+        wrapped: ComponentManifest = object.__getattribute__(self, "_wrapped")
+        return getattr(wrapped, name)
+
+    def __setattr__(self, name: str, value: Any) -> None:
+        overrides: dict[str, Any] = object.__getattribute__(self, "_overrides")
+        overrides[name] = value
+
+    def enable_codegen(self) -> None:
+        """Remove the to_code suppression, re-enabling code generation for this component.
+
+        Call this from ``override_manifest`` when the component needs its real (or a
+        custom stub) ``to_code`` to run during C++ unit test builds.
+        """
+        overrides: dict[str, Any] = object.__getattribute__(self, "_overrides")
+        overrides.pop("to_code", None)
+
+    def restore(self) -> None:
+        """Clear all overrides, reverting to the wrapped manifest's values."""
+        object.__getattribute__(self, "_overrides").clear()
+
+
+def set_testing_manifest(domain: str, manifest: ComponentManifestOverride) -> None:
+    """Install a testing manifest override into the component cache.
+
+    Called from the C++ unit test infrastructure when a component's test
+    directory provides an ``override_manifest`` function.
+    """
+    _replace_component_manifest(domain, manifest)

tests/unit_tests/test_loader.py

@@ -2,7 +2,104 @@
 
 from unittest.mock import MagicMock, patch
 
-from esphome.loader import ComponentManifest
+from esphome.loader import ComponentManifest, _replace_component_manifest, get_component
+from tests.testing_helpers import ComponentManifestOverride
+
+# ---------------------------------------------------------------------------
+# ComponentManifestOverride
+# ---------------------------------------------------------------------------
+
+
+def _make_manifest(*, to_code=None, dependencies=None) -> ComponentManifest:
+    """Return a ComponentManifest backed by a minimal mock module."""
+    mod = MagicMock()
+    mod.to_code = to_code
+    mod.DEPENDENCIES = dependencies or []
+    return ComponentManifest(mod)
+
+
+def test_testing_manifest_delegates_to_wrapped() -> None:
+    """Unoverridden attributes fall through to the wrapped manifest."""
+    inner = _make_manifest(dependencies=["wifi"])
+    tm = ComponentManifestOverride(inner)
+    assert tm.dependencies == ["wifi"]
+
+
+def test_testing_manifest_override_shadows_wrapped() -> None:
+    """An assigned attribute shadows the wrapped value."""
+    inner = _make_manifest(dependencies=["wifi"])
+    tm = ComponentManifestOverride(inner)
+    tm.dependencies = ["ble"]
+    assert tm.dependencies == ["ble"]
+    # Wrapped value unchanged
+    assert inner.dependencies == ["wifi"]
+
+
+def test_testing_manifest_to_code_suppression() -> None:
+    """Setting to_code=None suppresses code generation."""
+
+    async def real_to_code(config):
+        pass
+
+    inner = _make_manifest(to_code=real_to_code)
+    tm = ComponentManifestOverride(inner)
+    tm.to_code = None
+    assert tm.to_code is None
+
+
+def test_testing_manifest_enable_codegen_removes_suppression() -> None:
+    """enable_codegen() removes the to_code override, restoring the original."""
+
+    async def real_to_code(config):
+        pass
+
+    inner = _make_manifest(to_code=real_to_code)
+    tm = ComponentManifestOverride(inner)
+    tm.to_code = None
+    assert tm.to_code is None
+
+    tm.enable_codegen()
+    assert tm.to_code is real_to_code
+
+
+def test_testing_manifest_enable_codegen_preserves_other_overrides() -> None:
+    """enable_codegen() only removes to_code; other overrides survive."""
+    inner = _make_manifest(dependencies=["wifi"])
+    tm = ComponentManifestOverride(inner)
+    tm.to_code = None
+    tm.dependencies = ["ble"]
+
+    tm.enable_codegen()
+
+    assert tm.to_code is inner.to_code
+    assert tm.dependencies == ["ble"]
+
+
+def test_testing_manifest_restore_clears_all_overrides() -> None:
+    """restore() removes every override, reverting all attributes to wrapped values."""
+
+    async def real_to_code(config):
+        pass
+
+    inner = _make_manifest(to_code=real_to_code, dependencies=["wifi"])
+    tm = ComponentManifestOverride(inner)
+    tm.to_code = None
+    tm.dependencies = ["ble"]
+
+    tm.restore()
+
+    assert tm.to_code is real_to_code
+    assert tm.dependencies == ["wifi"]
+
+
+def test_replace_component_manifest_installs_override() -> None:
+    """_replace_component_manifest replaces the cached manifest for a domain."""
+    inner = _make_manifest()
+    override = ComponentManifestOverride(inner)
+
+    _replace_component_manifest("_test_dummy_domain", override)
+
+    assert get_component("_test_dummy_domain") is override
 
 
 def test_component_manifest_resources_with_filter_source_files() -> None:

tests/unit_tests/test_main.py

@@ -167,6 +167,13 @@ def mock_run_miniterm() -> Generator[Mock]:
         yield mock
 
 
+@pytest.fixture
+def mock_wait_for_serial_port() -> Generator[Mock]:
+    """Mock _wait_for_serial_port for testing."""
+    with patch("esphome.__main__._wait_for_serial_port") as mock:
+        yield mock
+
+
 @pytest.fixture
 def mock_upload_using_esptool() -> Generator[Mock]:
     """Mock upload_using_esptool for testing."""
@@ -1706,6 +1713,7 @@ def test_show_logs_serial(
     mock_get_port_type: Mock,
     mock_check_permissions: Mock,
     mock_run_miniterm: Mock,
+    mock_wait_for_serial_port: Mock,
 ) -> None:
     """Test show_logs with serial port."""
     setup_core(config={"logger": {}}, platform=PLATFORM_ESP32)