Merge branch 'dev' into configure_entity

tests/components/audio_file/common.yaml

@@ -3,3 +3,7 @@ audio_file:
     file:
       type: local
       path: $component_dir/test.wav
+
+media_source:
+  - platform: audio_file
+    id: audio_file_source

tests/components/ble_nus/test-uart.nrf52-adafruit.yaml

@@ -0,0 +1,4 @@
+ble_nus:
+  type: uart
+  tx_buffer_size: 160
+  rx_buffer_size: 160

tests/components/modbus/common.yaml

@@ -1,3 +1,5 @@
 modbus:
   id: mod_bus1
   flow_control_pin: ${flow_control_pin}
+  send_wait_time: 500ms
+  turnaround_time: 100ms

tests/dummy_main.cpp

@@ -12,7 +12,9 @@
 using namespace esphome;
 
 void setup() {
-  App.pre_setup("livingroom", "LivingRoom", false);
+  static char name[] = "livingroom";
+  static char friendly_name[] = "LivingRoom";
+  App.pre_setup(name, sizeof(name) - 1, friendly_name, sizeof(friendly_name) - 1);
   auto *log = new logger::Logger(115200);  // NOLINT
   log->pre_setup();
   log->set_uart_selection(logger::UART_SELECTION_UART0);

tests/integration/fixtures/external_components/uart_mock/__init__.py

@@ -71,6 +71,7 @@ RESPONSE_SCHEMA = cv.Schema(
     {
         cv.Required(CONF_EXPECT_TX): [cv.hex_uint8_t],
         cv.Required(CONF_INJECT_RX): [cv.hex_uint8_t],
+        cv.Optional(CONF_DELAY, default="0ms"): cv.positive_time_period_milliseconds,
     }
 )
 
@@ -151,7 +152,8 @@ async def to_code(config):
     for response in config[CONF_RESPONSES]:
         tx_data = response[CONF_EXPECT_TX]
         rx_data = response[CONF_INJECT_RX]
-        cg.add(var.add_response(tx_data, rx_data))
+        delay_ms = response[CONF_DELAY]
+        cg.add(var.add_response(tx_data, rx_data, delay_ms))
 
     for periodic in config[CONF_PERIODIC_RX]:
         data = periodic[CONF_DATA]

tests/integration/fixtures/external_components/uart_mock/uart_mock.cpp

@@ -36,8 +36,8 @@ void MockUartComponent::loop() {
   // component (e.g., LD2410) a chance to process each batch independently.
   if (this->injection_index_ < this->injections_.size()) {
     auto &injection = this->injections_[this->injection_index_];
-    uint32_t target_time = this->scenario_start_ms_ + this->cumulative_delay_ms_ + injection.delay_ms;
-    if (now >= target_time) {
+    uint32_t total_delay = this->cumulative_delay_ms_ + injection.delay_ms;
+    if (now - this->scenario_start_ms_ >= total_delay) {
       ESP_LOGD(TAG, "Injecting %zu RX bytes (injection %u)", injection.rx_data.size(), this->injection_index_);
       this->inject_to_rx_buffer(injection.rx_data);
       this->cumulative_delay_ms_ += injection.delay_ms;
@@ -52,6 +52,15 @@ void MockUartComponent::loop() {
       periodic.last_inject_ms = now;
     }
   }
+
+  // Process delayed responses
+  for (auto &response : this->responses_) {
+    if (response.delay_ms > 0 && response.last_match_ms > 0 && now - response.last_match_ms >= response.delay_ms) {
+      ESP_LOGD(TAG, "Injecting %zu RX bytes for delayed response", response.inject_rx.size());
+      this->inject_to_rx_buffer(response.inject_rx);
+      response.last_match_ms = 0;  // Reset to prevent repeated injection
+    }
+  }
 }
 
 void MockUartComponent::start_scenario() {
@@ -149,8 +158,9 @@ void MockUartComponent::add_injection(const std::vector<uint8_t> &rx_data, uint3
   this->injections_.push_back({rx_data, delay_ms});
 }
 
-void MockUartComponent::add_response(const std::vector<uint8_t> &expect_tx, const std::vector<uint8_t> &inject_rx) {
-  this->responses_.push_back({expect_tx, inject_rx});
+void MockUartComponent::add_response(const std::vector<uint8_t> &expect_tx, const std::vector<uint8_t> &inject_rx,
+                                     uint32_t delay_ms) {
+  this->responses_.push_back({expect_tx, inject_rx, delay_ms, 0});
 }
 
 void MockUartComponent::add_periodic_rx(const std::vector<uint8_t> &data, uint32_t interval_ms) {
@@ -166,7 +176,13 @@ void MockUartComponent::try_match_response_() {
     size_t offset = this->tx_buffer_.size() - response.expect_tx.size();
     if (std::equal(response.expect_tx.begin(), response.expect_tx.end(), this->tx_buffer_.begin() + offset)) {
       ESP_LOGD(TAG, "TX match found, injecting %zu RX bytes", response.inject_rx.size());
-      this->inject_to_rx_buffer(response.inject_rx);
+      if (response.delay_ms > 0) {
+        ESP_LOGD(TAG, "Delaying response by %u ms", response.delay_ms);
+        // Schedule the response injection as a future injection
+        response.last_match_ms = App.get_loop_component_start_time();
+      } else {
+        this->inject_to_rx_buffer(response.inject_rx);
+      }
       this->tx_buffer_.clear();
       return;
     }

tests/integration/fixtures/external_components/uart_mock/uart_mock.h

@@ -34,7 +34,8 @@ class MockUartComponent : public uart::UARTComponent, public Component {
 
   // Scenario configuration - called from generated code
   void add_injection(const std::vector<uint8_t> &rx_data, uint32_t delay_ms);
-  void add_response(const std::vector<uint8_t> &expect_tx, const std::vector<uint8_t> &inject_rx);
+  void add_response(const std::vector<uint8_t> &expect_tx, const std::vector<uint8_t> &inject_rx,
+                    uint32_t delay_ms = 0);
   void add_periodic_rx(const std::vector<uint8_t> &data, uint32_t interval_ms);
 
   void start_scenario();
@@ -64,6 +65,8 @@ class MockUartComponent : public uart::UARTComponent, public Component {
   struct Response {
     std::vector<uint8_t> expect_tx;
     std::vector<uint8_t> inject_rx;
+    uint32_t delay_ms;
+    uint32_t last_match_ms{0};
   };
   std::vector<Response> responses_;
   std::vector<uint8_t> tx_buffer_;

tests/integration/fixtures/uart_mock_modbus.yaml

@@ -25,20 +25,64 @@ uart_mock:
     auto_start: false
     debug:
     responses:
-      - expect_tx: [0x01, 0x03, 0x00, 0x03, 0x00, 0x01, 0x74, 0x0A] # Read holding register 1 on device 1
+      - expect_tx: [0x01, 0x03, 0x00, 0x03, 0x00, 0x01, 0x74, 0x0A] # Read holding register 3 on device 1 (basic_register)
         inject_rx: [0x01, 0x03, 0x02, 0x01, 0x03, 0xF9, 0xD5] # Return value 0x0103 (hex) = 259 (dec)
+      - expect_tx: [0x01, 0x03, 0x00, 0x05, 0x00, 0x01, 0x94, 0x0B] # Read holding register 5 on device 1 (delayed_response)
+        delay: 100ms # Shorter than modbus send_wait_time of 200ms, should succeed
+        inject_rx: [0x01, 0x03, 0x02, 0x00, 0xFF, 0xF8, 0x04] # Return value 0x00FF (hex) = 255 (dec)
+      - expect_tx: [0x02, 0x03, 0x00, 0x07, 0x00, 0x01, 0x35, 0xF8] # Read holding register 7 on device 2 (late_response)
+        delay: 300ms # Longer than modbus send_wait_time of 200ms, should cause timeout
+        inject_rx: [0x02, 0x03, 0x02, 0x00, 0xF0, 0xFC, 0x00] # Return value 0x00F0 (hex) = 240 (dec)
+      - expect_tx: [0x03, 0x03, 0x00, 0x09, 0x00, 0x01, 0x55, 0xEA] # Read holding register 9 on device 3 (no_response)
+        inject_rx: [] # No response, should cause timeout
+      - expect_tx: [0x01, 0x03, 0x00, 0x0A, 0x00, 0x01, 0xA4, 0x08] # Read holding register A on device 1 (exception_response)
+        inject_rx: [0x01, 0x83, 0x02, 0xC0, 0xF1] # Exception response with code 2 (illegal data address)
 
 modbus:
   uart_id: virtual_uart_dev
+  send_wait_time: 200ms
+  turnaround_time: 10ms
 
 modbus_controller:
-  address: 1
+  - address: 1
+    id: modbus_controller_ok
+    max_cmd_retries: 0
+    update_interval: 1s
+  - address: 2
+    id: modbus_controller_slow
+    max_cmd_retries: 0
+    update_interval: 1s
+  - address: 3
+    id: modbus_controller_offline
+    max_cmd_retries: 0
+    update_interval: 1s
 
 sensor:
   - platform: modbus_controller
     name: "basic_register"
     address: 0x03
     register_type: holding
+    modbus_controller_id: modbus_controller_ok
+  - platform: modbus_controller
+    name: "delayed_response"
+    address: 0x05
+    register_type: holding
+    modbus_controller_id: modbus_controller_ok
+  - platform: modbus_controller
+    name: "late_response"
+    address: 0x07
+    register_type: holding
+    modbus_controller_id: modbus_controller_slow
+  - platform: modbus_controller
+    name: "no_response"
+    address: 0x09
+    register_type: holding
+    modbus_controller_id: modbus_controller_offline
+  - platform: modbus_controller
+    name: "exception_response"
+    address: 0x0A
+    register_type: holding
+    modbus_controller_id: modbus_controller_ok
 
 button:
   - platform: template

tests/integration/fixtures/uart_mock_modbus_timing.yaml

@@ -46,10 +46,12 @@ uart_mock:
 
 modbus:
   uart_id: virtual_uart_dev
+  turnaround_time: 10ms
 
 sensor:
   - platform: sdm_meter
     address: 2
+    update_interval: 1s
     phase_a:
       voltage:
         name: sdm_voltage

tests/integration/test_uart_mock_modbus.py

@@ -39,9 +39,17 @@ async def test_uart_mock_modbus(
     # Track sensor state updates (after initial state is swallowed)
     sensor_states: dict[str, list[float]] = {
         "basic_register": [],
+        "delayed_response": [],
+        "late_response": [],
+        "no_response": [],
+        "exception_response": [],
     }
 
     basic_register_changed = loop.create_future()
+    delayed_response_changed = loop.create_future()
+    late_response_changed = loop.create_future()
+    no_response_changed = loop.create_future()
+    exception_response_changed = loop.create_future()
 
     def on_state(state: EntityState) -> None:
         if isinstance(state, SensorState) and not state.missing_state:
@@ -54,6 +62,23 @@ async def test_uart_mock_modbus(
                     and not basic_register_changed.done()
                 ):
                     basic_register_changed.set_result(True)
+                elif (
+                    sensor_name == "delayed_response"
+                    and state.state == 255.0
+                    and not delayed_response_changed.done()
+                ):
+                    delayed_response_changed.set_result(True)
+                elif (
+                    sensor_name == "late_response" and not late_response_changed.done()
+                ):
+                    late_response_changed.set_result(True)
+                elif sensor_name == "no_response" and not no_response_changed.done():
+                    no_response_changed.set_result(True)
+                elif (
+                    sensor_name == "exception_response"
+                    and not exception_response_changed.done()
+                ):
+                    exception_response_changed.set_result(True)
 
     async with (
         run_compiled(yaml_config),
@@ -79,20 +104,52 @@ async def test_uart_mock_modbus(
         assert start_btn is not None, "Start Scenario button not found"
         client.button_command(start_btn.key)
 
+        try:
+            await asyncio.wait_for(delayed_response_changed, timeout=2.0)
+        except TimeoutError:
+            pytest.fail(
+                f"Timeout waiting for delayed_response change. Received sensor states:\n"
+                f"  delayed_response: {sensor_states['delayed_response']}\n"
+            )
+
+        try:
+            await asyncio.wait_for(late_response_changed, timeout=2.0)
+            pytest.fail(
+                f"late_response change should not have been triggered, but was. Received sensor states:\n"
+                f"  late_response: {sensor_states['late_response']}\n"
+            )
+        except TimeoutError:
+            pass  # Expected timeout since we never inject a response for late_response
+
+        try:
+            await asyncio.wait_for(no_response_changed, timeout=2.0)
+            pytest.fail(
+                f"no_response change should not have been triggered, but was. Received sensor states:\n"
+                f"  no_response: {sensor_states['no_response']}\n"
+            )
+        except TimeoutError:
+            pass  # Expected timeout since we never inject a response for no_response
+
         # Wait for basic register to be updated with successful parse
         try:
-            await asyncio.wait_for(basic_register_changed, timeout=15.0)
+            await asyncio.wait_for(basic_register_changed, timeout=2.0)
         except TimeoutError:
             pytest.fail(
                 f"Timeout waiting for Basic Register change. Received sensor states:\n"
                 f"  basic_register: {sensor_states['basic_register']}\n"
             )
 
+        try:
+            await asyncio.wait_for(exception_response_changed, timeout=2.0)
+            pytest.fail(
+                f"exception_response change should not have been triggered, but was. Received sensor states:\n"
+                f"  exception_response: {sensor_states['exception_response']}\n"
+            )
+        except TimeoutError:
+            pass
+
 
 @pytest.mark.asyncio
-@pytest.mark.xfail(
-    reason="There is a bug in UART which will timeout for long responses."
-)
 async def test_uart_mock_modbus_timing(
     yaml_config: str,
     run_compiled: RunCompiledFunction,
@@ -155,7 +212,7 @@ async def test_uart_mock_modbus_timing(
 
         # Wait for voltage to be updated with successful parse
         try:
-            await asyncio.wait_for(voltage_changed, timeout=15.0)
+            await asyncio.wait_for(voltage_changed, timeout=2.0)
         except TimeoutError:
             pytest.fail(
                 f"Timeout waiting for SDM voltage change. Received sensor states:\n"

tests/unit_tests/components/test_rp2040_generate_boards.py

@@ -0,0 +1,273 @@
+"""Tests for rp2040 generate_boards.py."""
+
+from __future__ import annotations
+
+import json
+from pathlib import Path
+import textwrap
+
+import pytest
+
+from esphome.components.rp2040.generate_boards import load_boards, parse_variant_pins
+
+PICO_PINS_HEADER = textwrap.dedent("""\
+    #pragma once
+    #define PIN_LED        (25u)
+    #define PIN_SERIAL1_TX (0u)
+    #define PIN_SERIAL1_RX (1u)
+    #define PIN_WIRE0_SDA  (4u)
+    #define PIN_WIRE0_SCL  (5u)
+    #define PIN_WIRE1_SDA  (26u)
+    #define PIN_WIRE1_SCL  (27u)
+    #define PIN_SPI0_MISO  (16u)
+    #define PIN_SPI0_MOSI  (19u)
+    #define PIN_SPI0_SCK   (18u)
+    #define PIN_SPI0_SS    (17u)
+    #include "../generic/common.h"
+""")
+
+PICOW_PINS_HEADER = textwrap.dedent("""\
+    #pragma once
+    #include <cyw43_wrappers.h>
+    #define PIN_LED        (64u)
+    #define PIN_WIRE0_SDA  (4u)
+    #define PIN_WIRE0_SCL  (5u)
+    #include "../generic/common.h"
+""")
+
+
+@pytest.fixture()
+def arduino_pico(tmp_path: Path) -> Path:
+    """Create a minimal arduino-pico directory structure."""
+    json_dir = tmp_path / "tools" / "json"
+    json_dir.mkdir(parents=True)
+    variants_dir = tmp_path / "variants"
+    variants_dir.mkdir()
+
+    generic_dir = variants_dir / "generic"
+    generic_dir.mkdir()
+    (generic_dir / "common.h").write_text("#pragma once\n")
+
+    return tmp_path
+
+
+def _add_board(
+    arduino_pico: Path,
+    board_name: str,
+    mcu: str = "rp2040",
+    variant: str | None = None,
+    vendor: str = "",
+    name: str | None = None,
+    pins_header: str | None = None,
+) -> None:
+    """Add a board JSON and variant to the fake arduino-pico tree."""
+    if variant is None:
+        variant = board_name
+    if name is None:
+        name = board_name
+
+    json_dir = arduino_pico / "tools" / "json"
+    variants_dir = arduino_pico / "variants"
+
+    board_json = {
+        "build": {
+            "mcu": mcu,
+            "variant": variant,
+        },
+        "name": name,
+        "vendor": vendor,
+    }
+    (json_dir / f"{board_name}.json").write_text(json.dumps(board_json))
+
+    variant_dir = variants_dir / variant
+    variant_dir.mkdir(exist_ok=True)
+    if pins_header is not None:
+        (variant_dir / "pins_arduino.h").write_text(pins_header)
+
+
+def test_parse_basic_pins(tmp_path: Path) -> None:
+    variant_dir = tmp_path / "rpipico"
+    variant_dir.mkdir()
+    (variant_dir / "pins_arduino.h").write_text(PICO_PINS_HEADER)
+
+    pins = parse_variant_pins(variant_dir)
+    assert pins["LED"] == 25
+    assert pins["SDA"] == 4
+    assert pins["SCL"] == 5
+    assert pins["SDA1"] == 26
+    assert pins["SCL1"] == 27
+    assert pins["MISO"] == 16
+    assert pins["MOSI"] == 19
+    assert pins["SCK"] == 18
+    assert pins["SS"] == 17
+    assert pins["TX"] == 0
+    assert pins["RX"] == 1
+
+
+def test_parse_cyw43_led_pin(tmp_path: Path) -> None:
+    variant_dir = tmp_path / "rpipicow"
+    variant_dir.mkdir()
+    (variant_dir / "pins_arduino.h").write_text(PICOW_PINS_HEADER)
+
+    pins = parse_variant_pins(variant_dir)
+    assert pins["LED"] == 64
+
+
+def test_parse_missing_header(tmp_path: Path) -> None:
+    variant_dir = tmp_path / "noheader"
+    variant_dir.mkdir()
+    assert parse_variant_pins(variant_dir) == {}
+
+
+def test_parse_unmapped_defines_ignored(tmp_path: Path) -> None:
+    variant_dir = tmp_path / "custom"
+    variant_dir.mkdir()
+    (variant_dir / "pins_arduino.h").write_text(
+        "#define PIN_NEOPIXEL (16u)\n#define PIN_LED (25u)\n"
+    )
+
+    pins = parse_variant_pins(variant_dir)
+    assert "NEOPIXEL" not in pins
+    assert pins["LED"] == 25
+
+
+def test_load_basic_board(arduino_pico: Path) -> None:
+    _add_board(
+        arduino_pico,
+        "rpipico",
+        vendor="Raspberry Pi",
+        name="Pico",
+        pins_header=PICO_PINS_HEADER,
+    )
+
+    board_pins, boards = load_boards(arduino_pico)
+
+    assert "rpipico" in boards
+    assert boards["rpipico"]["name"] == "Raspberry Pi Pico"
+    assert boards["rpipico"]["mcu"] == "rp2040"
+    assert boards["rpipico"]["max_pin"] == 29
+
+    assert "rpipico" in board_pins
+    assert board_pins["rpipico"]["LED"] == 25
+    assert board_pins["rpipico"]["SDA"] == 4
+
+
+def test_load_rp2350_board(arduino_pico: Path) -> None:
+    _add_board(
+        arduino_pico,
+        "rpipico2",
+        mcu="rp2350",
+        vendor="Raspberry Pi",
+        name="Pico 2",
+        pins_header=PICO_PINS_HEADER,
+    )
+
+    _, boards = load_boards(arduino_pico)
+
+    assert boards["rpipico2"]["mcu"] == "rp2350"
+    assert boards["rpipico2"]["max_pin"] == 47
+
+
+def test_cyw43_board_has_max_virtual_pin(arduino_pico: Path) -> None:
+    _add_board(
+        arduino_pico,
+        "rpipicow",
+        vendor="Raspberry Pi",
+        name="Pico W",
+        pins_header=PICOW_PINS_HEADER,
+    )
+
+    _, boards = load_boards(arduino_pico)
+
+    assert boards["rpipicow"]["max_virtual_pin"] == 64
+
+
+def test_non_cyw43_board_has_no_max_virtual_pin(arduino_pico: Path) -> None:
+    _add_board(
+        arduino_pico,
+        "rpipico",
+        vendor="Raspberry Pi",
+        name="Pico",
+        pins_header=PICO_PINS_HEADER,
+    )
+
+    _, boards = load_boards(arduino_pico)
+
+    assert "max_virtual_pin" not in boards["rpipico"]
+
+
+def test_board_without_variant_header(arduino_pico: Path) -> None:
+    _add_board(arduino_pico, "novariant", name="No Variant")
+
+    board_pins, boards = load_boards(arduino_pico)
+
+    assert "novariant" in boards
+    assert "novariant" not in board_pins
+
+
+def test_shared_variant_deduplicates(arduino_pico: Path) -> None:
+    """Two boards sharing the same variant should alias."""
+    _add_board(arduino_pico, "base_board", pins_header=PICO_PINS_HEADER)
+    _add_board(arduino_pico, "alias_board", variant="base_board")
+
+    board_pins, _ = load_boards(arduino_pico)
+
+    assert board_pins["base_board"] == parse_variant_pins(
+        arduino_pico / "variants" / "base_board"
+    )
+    assert board_pins["alias_board"] == "base_board"
+
+
+def test_display_name_with_vendor(arduino_pico: Path) -> None:
+    _add_board(arduino_pico, "testboard", vendor="Acme", name="Widget")
+    _, boards = load_boards(arduino_pico)
+    assert boards["testboard"]["name"] == "Acme Widget"
+
+
+def test_display_name_without_vendor(arduino_pico: Path) -> None:
+    _add_board(arduino_pico, "testboard", vendor="", name="Widget")
+    _, boards = load_boards(arduino_pico)
+    assert boards["testboard"]["name"] == "Widget"
+
+
+def test_unknown_mcu_gets_default_max_pin(arduino_pico: Path) -> None:
+    _add_board(arduino_pico, "future", mcu="rp2450", pins_header=PICO_PINS_HEADER)
+    _, boards = load_boards(arduino_pico)
+    assert boards["future"]["max_pin"] == 29
+
+
+def test_placeholder_pins_filtered_out(arduino_pico: Path) -> None:
+    """Pins with placeholder values like 99 should be filtered out."""
+    header = textwrap.dedent("""\
+        #pragma once
+        #define PIN_LED        (25u)
+        #define PIN_WIRE0_SDA  (4u)
+        #define PIN_WIRE0_SCL  (5u)
+        #define PIN_WIRE1_SDA  (99u)
+        #define PIN_WIRE1_SCL  (99u)
+    """)
+    _add_board(arduino_pico, "placeholder", pins_header=header)
+
+    board_pins, boards = load_boards(arduino_pico)
+
+    assert "SDA1" not in board_pins["placeholder"]
+    assert "SCL1" not in board_pins["placeholder"]
+    assert board_pins["placeholder"]["LED"] == 25
+    assert "max_virtual_pin" not in boards["placeholder"]
+
+
+def test_placeholder_pins_not_treated_as_virtual(arduino_pico: Path) -> None:
+    """Pin 99 should not cause max_virtual_pin to be set."""
+    header = textwrap.dedent("""\
+        #pragma once
+        #define PIN_LED        (64u)
+        #define PIN_WIRE0_SDA  (4u)
+        #define PIN_WIRE0_SCL  (5u)
+        #define PIN_SPI0_MISO  (99u)
+    """)
+    _add_board(arduino_pico, "badpin", pins_header=header)
+
+    board_pins, boards = load_boards(arduino_pico)
+
+    assert "MISO" not in board_pins["badpin"]
+    assert boards["badpin"]["max_virtual_pin"] == 64

tests/unit_tests/core/test_config.py

@@ -23,6 +23,7 @@ from esphome.const import (
 from esphome.core import CORE, config
 from esphome.core.config import (
     Area,
+    make_app_name_cpp,
     preload_core_config,
     valid_include,
     valid_project_name,
@@ -969,3 +970,79 @@ def test_config_hash_different_for_different_configs() -> None:
     hash2 = CORE.config_hash
 
     assert hash1 != hash2
+
+
+def test_make_app_name_cpp_no_mac_simple() -> None:
+    """Test simple name without MAC suffix returns string literal."""
+    cpp_expr, global_decl, byte_len = make_app_name_cpp(
+        "my-device", "buf", "-", add_mac_suffix=False
+    )
+    assert cpp_expr == '"my-device"'
+    assert global_decl is None
+    assert byte_len == 9
+
+
+def test_make_app_name_cpp_no_mac_empty() -> None:
+    """Test empty name without MAC suffix."""
+    cpp_expr, global_decl, byte_len = make_app_name_cpp(
+        "", "buf", "-", add_mac_suffix=False
+    )
+    assert cpp_expr == '""'
+    assert global_decl is None
+    assert byte_len == 0
+
+
+def test_make_app_name_cpp_mac_suffix() -> None:
+    """Test name with MAC suffix emits static buffer."""
+    cpp_expr, global_decl, byte_len = make_app_name_cpp(
+        "my-device", "esphome_app_name_buf", "-", add_mac_suffix=True
+    )
+    assert cpp_expr == "esphome_app_name_buf"
+    assert global_decl is not None
+    assert "static char esphome_app_name_buf[]" in global_decl
+    assert "my-device-XXXXXX" in global_decl
+    assert byte_len == len("my-device-XXXXXX")
+
+
+def test_make_app_name_cpp_mac_suffix_empty() -> None:
+    """Test empty name with MAC suffix emits empty static buffer."""
+    cpp_expr, global_decl, byte_len = make_app_name_cpp(
+        "", "esphome_app_name_buf", "-", add_mac_suffix=True
+    )
+    assert cpp_expr == "esphome_app_name_buf"
+    assert global_decl is not None
+    assert "static char esphome_app_name_buf[]" in global_decl
+    assert byte_len == 0
+
+
+def test_make_app_name_cpp_mac_suffix_space_sep() -> None:
+    """Test friendly name uses space separator for MAC suffix."""
+    cpp_expr, global_decl, byte_len = make_app_name_cpp(
+        "My Device", "esphome_app_friendly_name_buf", " ", add_mac_suffix=True
+    )
+    assert cpp_expr == "esphome_app_friendly_name_buf"
+    assert global_decl is not None
+    assert "My Device XXXXXX" in global_decl
+    assert byte_len == len("My Device XXXXXX")
+
+
+def test_make_app_name_cpp_non_ascii_utf8_length() -> None:
+    """Test non-ASCII characters use UTF-8 byte length."""
+    _, global_decl, byte_len = make_app_name_cpp(
+        "café", "buf", "-", add_mac_suffix=False
+    )
+    assert byte_len == len("café".encode())  # 5 bytes, not 4 chars
+    assert global_decl is None
+
+
+def test_make_app_name_cpp_non_ascii_mac_suffix_utf8_length() -> None:
+    """Test non-ASCII with MAC suffix uses UTF-8 byte length."""
+    _, _, byte_len = make_app_name_cpp("café", "buf", "-", add_mac_suffix=True)
+    assert byte_len == len("café-XXXXXX".encode())
+
+
+def test_make_app_name_cpp_special_chars_escaped() -> None:
+    """Test special characters are properly escaped in C++ string."""
+    cpp_expr, _, _ = make_app_name_cpp('my "device"', "buf", "-", add_mac_suffix=False)
+    # cpp_string_escape uses octal escapes for quotes
+    assert '"' not in cpp_expr[1:-1]  # no unescaped quotes inside the outer quotes

tests/unit_tests/core/test_entity_helpers.py

@@ -23,6 +23,7 @@ from esphome.core.entity_helpers import (
     _setup_entity_impl,
     entity_duplicate_validator,
     get_base_entity_object_id,
+    register_icon,
     setup_entity,
 )
 from esphome.cpp_generator import MockObj
@@ -904,6 +905,22 @@ def test_register_string_overflow() -> None:
         _register_string("overflow", category, 3, "test")
 
 
+def test_register_icon_max_length() -> None:
+    """Test register_icon rejects icons exceeding 63 characters."""
+    # 63 chars should succeed
+    max_icon = "mdi:" + "a" * 59  # 63 total
+    idx = register_icon(max_icon)
+    assert idx > 0
+
+    # 64 chars should fail
+    too_long = "mdi:" + "a" * 60  # 64 total
+    with pytest.raises(ValueError, match="Icon string too long"):
+        register_icon(too_long)
+
+    # Empty string returns 0
+    assert register_icon("") == 0
+
+
 @pytest.mark.asyncio
 async def test_setup_entity_with_entity_category(
     setup_test_environment: list[str],

tests/unit_tests/test_config_validation.py

@@ -148,6 +148,18 @@ def test_icon__invalid():
         config_validation.icon("foo")
 
 
+def test_icon__max_length():
+    """Test that icons exceeding 63 characters are rejected."""
+    # Exactly 63 chars should pass
+    max_icon = "mdi:" + "a" * 59  # 63 chars total
+    assert config_validation.icon(max_icon) == max_icon
+
+    # 64 chars should fail
+    too_long = "mdi:" + "a" * 60  # 64 chars total
+    with pytest.raises(Invalid, match="Icon string is too long"):
+        config_validation.icon(too_long)
+
+
 @pytest.mark.parametrize("value", ("True", "YES", "on", "enAblE", True))
 def test_boolean__valid_true(value):
     assert config_validation.boolean(value) is True