[nrf52] Fake a larger flash in testing mode (#20439)

esphome/components/nrf52/__init__.py

@@ -12,6 +12,7 @@ from esphome.build_helpers import pch
 from esphome.build_helpers.ccache import resolve_ccache_path
 import esphome.codegen as cg
 from esphome.components.zephyr import (
+    Section,
     add_extra_script,
     copy_files as zephyr_copy_files,
     zephyr_add_overlay,
@@ -126,11 +127,37 @@ def set_core_data(config: ConfigType) -> ConfigType:
     CORE.data[KEY_CORE][KEY_TARGET_FRAMEWORK] = KEY_ZEPHYR
 
     if config[KEY_BOOTLOADER] in BOOTLOADER_CONFIG:
-        zephyr_add_pm_static(BOOTLOADER_CONFIG[config[KEY_BOOTLOADER]])
+        sections = BOOTLOADER_CONFIG[config[KEY_BOOTLOADER]]
+        if CORE.testing_mode:
+            sections = _testing_mode_sections(sections)
+        zephyr_add_pm_static(sections)
 
     return config
 
 
+# In testing mode, fake a larger flash to allow linking grouped component
+# tests. The nRF52840 has 1 MB and a mcumgr OTA config halves the app slot,
+# which an openthread config alone fills; CI images are never flashed.
+NRF52840_FLASH_SIZE = 0x100000
+TESTING_FLASH_SIZE = 0x400000
+
+
+def _testing_mode_sections(sections: list[Section]) -> list[Section]:
+    """Move a bootloader pinned to the end of the real flash to the end of the
+    faked one, so the partition manager still sees a single gap for the app."""
+    return [
+        Section(
+            section.name,
+            section.address + TESTING_FLASH_SIZE - NRF52840_FLASH_SIZE,
+            section.size,
+            section.region,
+        )
+        if section.end_address == NRF52840_FLASH_SIZE
+        else section
+        for section in sections
+    ]
+
+
 _TOOLCHAINS = (Toolchain.PLATFORMIO, Toolchain.SDK_NRF)
 _resolve_toolchain = cv.resolve_toolchain("nRF52", _TOOLCHAINS, Toolchain.SDK_NRF)
 
@@ -381,6 +408,15 @@ async def to_code(config: ConfigType) -> None:
     zephyr_setup_preferences()
     zephyr_to_code(config)
 
+    if CORE.testing_mode:
+        zephyr_add_overlay(
+            f"""
+                &flash0 {{
+                    reg = <0x0 {TESTING_FLASH_SIZE:#x}>;
+                }};
+            """
+        )
+
     if dfu_config := config.get(CONF_DFU):
         CORE.add_job(_dfu_to_code, dfu_config)
     framework_ver: cv.Version = CORE.data[KEY_CORE][KEY_FRAMEWORK_VERSION]

esphome/components/zephyr_mcumgr/ota/__init__.py

@@ -13,6 +13,7 @@ from esphome.components.zephyr import (
 from esphome.components.zephyr.const import (
     BOOTLOADER_MCUBOOT,
     KEY_BOOTLOADER,
+    KEY_PM_STATIC,
     KEY_SYSBUILD,
 )
 from esphome.components.zephyr_ble_server import request_ble_l2cap_mtu
@@ -207,10 +208,11 @@ async def to_code(config: ConfigType) -> None:
 
     bootloader = zephyr_data()[KEY_BOOTLOADER]
     if bootloader != BOOTLOADER_MCUBOOT:
-        sections = BOOTLOADER_CONFIG[bootloader]
-        # Derive partition addresses from the SoftDevice and bootloader sections so
-        # that the DTS flash map matches what the Partition Manager produces:
+        # Derive partition addresses from the SoftDevice and bootloader sections
+        # registered with the Partition Manager (moved in testing mode) so that
+        # the DTS flash map matches what it produces:
         #   MCUboot sits immediately after the SoftDevice, then slot0, then slot1.
+        sections = zephyr_data()[KEY_PM_STATIC]
         mcuboot_size = 0x9000
         sd_end = next(s.address + s.size for s in sections if "SoftDevice" in s.name)
         bl_start = next(s.address for s in sections if "Adafruit" in s.name)

tests/unit_tests/components/nrf52/test_testing_mode_flash.py

@@ -0,0 +1,30 @@
+"""Testing mode fakes a larger flash so grouped component tests link."""
+
+from esphome.components import nrf52
+from esphome.components.nrf52.boards import BOOTLOADER_CONFIG
+from esphome.components.nrf52.const import BOOTLOADER_ADAFRUIT_NRF52_SD140_V7
+from esphome.components.zephyr import Section
+
+
+def test_testing_mode_sections_move_only_the_bootloader() -> None:
+    """The bootloader pinned to the end of flash follows the faked end; the
+    SoftDevice at the start stays."""
+    sections = nrf52._testing_mode_sections(
+        BOOTLOADER_CONFIG[BOOTLOADER_ADAFRUIT_NRF52_SD140_V7]
+    )
+
+    assert [(s.name, s.address, s.size) for s in sections] == [
+        ("SoftDevice", 0x0, 0x27000),
+        (
+            "Adafruit_nRF52_Bootloader",
+            nrf52.TESTING_FLASH_SIZE - 0xC000,
+            0xC000,
+        ),
+    ]
+    assert sections[1].end_address == nrf52.TESTING_FLASH_SIZE
+
+
+def test_testing_mode_sections_leave_unpinned_sections() -> None:
+    section = Section("other", 0x50000, 0x1000, "flash_primary")
+
+    assert nrf52._testing_mode_sections([section]) == [section]