test(freertos): Added support for gcov code coverage for FreeRTOS source files

This commit adds the following:
- Added support to FreeRTOS component to report code coverage using gcov
  and app trace.
- Added a new sdkconfig.ci.code_coverage for code coverage tests.
- Added a new Kconfig option CONFIG_FREERTOS_ENABLE_COVERAGE_TESTS to
  control the code instrumentation.
- Added an idf_component.yml file to the test_app to fetch the esp_gcov
  component from the component registry.
- Updated the README to explain how to take code coverage data.

components/freertos/test_apps/freertos/CMakeLists.txt

@@ -19,3 +19,36 @@ set(EXTRA_COMPONENT_DIRS
 set(COMPONENTS main esp_psram)
 
 project(freertos_test)
+
+# ============================================================================
+# Code Coverage Instrumentation
+# ============================================================================
+# When CONFIG_FREERTOS_ENABLE_COVERAGE_TESTS is enabled, instrument FreeRTOS
+# kernel, port, and ESP additions source files for coverage analysis.
+
+if(CONFIG_FREERTOS_ENABLE_COVERAGE_TESTS)
+    # Get the FreeRTOS component library and directory
+    idf_component_get_property(freertos_lib freertos COMPONENT_LIB)
+    idf_component_get_property(freertos_dir freertos COMPONENT_DIR)
+
+    # Add coverage flags to the entire FreeRTOS component
+    target_compile_options(${freertos_lib} PRIVATE "--coverage")
+    target_link_options(${freertos_lib} PRIVATE "--coverage")
+
+    # Create coverage report generation targets
+    file(TO_NATIVE_PATH "${CMAKE_CURRENT_BINARY_DIR}/coverage_report" _coverage_report_path)
+
+    idf_create_coverage_report(
+        ${_coverage_report_path}
+        SOURCE_DIR ${freertos_dir}
+        GCOV_OPTIONS "--gcov-ignore-parse-errors=negative_hits.warn"
+    )
+    idf_clean_coverage_report(${_coverage_report_path})
+
+    message(STATUS "================================================")
+    message(STATUS "FreeRTOS code coverage instrumentation enabled for test app")
+    message(STATUS "Coverage report will be generated in: ${_coverage_report_path}")
+    message(STATUS "Coverage root directory: ${freertos_dir}")
+    message(STATUS "Use 'idf.py gcovr-report' to generate coverage report after running tests")
+    message(STATUS "Use 'idf.py cov-data-clean' to clean coverage data")
+endif()

components/freertos/test_apps/freertos/README.md

@@ -1,2 +1,70 @@
 | Supported Targets | ESP32 | ESP32-C2 | ESP32-C3 | ESP32-C5 | ESP32-C6 | ESP32-C61 | ESP32-H2 | ESP32-H21 | ESP32-H4 | ESP32-P4 | ESP32-S2 | ESP32-S3 |
 | ----------------- | ----- | -------- | -------- | -------- | -------- | --------- | -------- | --------- | -------- | -------- | -------- | -------- |
+
+
+
+## Manual Code Coverage Workflow
+
+This test_app can be set up to enable FreeRTOS code coverage using GCOV via JTAG and AppTrace.
+
+Follow these steps to manually build, flash, run, and collect code coverage from a FreeRTOS app:
+
+### 1. **Configure the project and build the application**
+The sdkconfig.ci.code_coverage enables code coverage settings and other FreeRTOS options to maximize coverage.
+```sh
+idf.py set-target <target>      # e.g., esp32s3
+idf.py -DSDKCONFIG_DEFAULTS="sdkconfig.defaults;sdkconfig.ci.code_coverage" build flash monitor
+```
+
+### 2. **Flash the Device**
+```sh
+idf.py -p <PORT> flash
+```
+
+### 3. **Launch OpenOCD**
+Start OpenOCD in a new terminal (adjust for your board/target if needed):
+```sh
+openocd -f board/esp32<target>-builtin.cfg
+```
+
+### 4. **Run Tests**
+Interact with the device over serial (`idf.py monitor -p <PORT>`) and run tests.
+
+### 5. **Collect Coverage Data**
+Flush coverage data regularly, and collect `.gcda` files from the device using a telnet session
+```sh
+telnet localhost 4444
+```
+Then run
+```sh
+esp gcov
+```
+
+All `.gcda` files will be retrieved into your build directory.
+Make sure to regularly collect `.gcda` files to avoid memory overflow problems.
+Coverage data should be collected before tests that reset the target.
+The coverage data is cumulative.
+
+### 6. **Generate Coverage Report**
+Adjust the `gcov` tool to be used based on the target
+```sh
+xtensa-esp32s3-elf-gcov -b \
+  ../esp-idf/freertos/CMakeFiles/__idf_freertos.dir/FreeRTOS-Kernel/*.gcda
+
+xtensa-esp32s3-elf-gcov -b \
+  ../esp-idf/freertos/CMakeFiles/__idf_freertos.dir/esp_additions/*gcda
+```
+Then run:
+```sh
+mkdir coverage_report
+cd coverage_report
+mkdir html
+▶ gcovr \
+  --gcov-use-existing-files \
+  --gcov-keep \
+  --root $IDF_PATH/components/freertos \
+  --html-details \
+  --output html/index.html \
+  .
+```
+This generates a detailed, navigable HTML coverage report in `html` folder.

components/freertos/test_apps/freertos/main/Kconfig.projbuild

@@ -0,0 +1,14 @@
+menu "FreeRTOS Test App Configuration"
+
+    config FREERTOS_ENABLE_COVERAGE_TESTS
+        bool "Enable code coverage instrumentation for FreeRTOS"
+        depends on ESP_GCOV_ENABLE
+        default n
+        help
+            When enabled, FreeRTOS kernel, port, and ESP additions source files will be compiled with
+            code coverage instrumentation flags (--coverage) to enable GCOV code coverage testing.
+
+            Note: This option will increase binary size and may impact performance. It should only be
+            enabled when running coverage tests.
+
+endmenu

components/freertos/test_apps/freertos/main/idf_component.yml

@@ -0,0 +1,7 @@
+## IDF Component Manager Manifest File
+dependencies:
+  ## Required IDF version
+  idf:
+    version: '>=6.0'
+  # # Put list of dependencies here
+  espressif/esp_gcov: ^1

components/freertos/test_apps/freertos/sdkconfig.ci.code_coverage

@@ -0,0 +1,103 @@
+# Code Coverage Configuration for FreeRTOS Tests
+# This is a configuration file for maximum code coverage.
+# It includes all necessary settings for GCOV coverage instrumentation and enables
+# many optional FreeRTOS features, hooks, and debugging options to maximize coverage.
+
+# ============================================================================
+# GCOV Coverage Infrastructure
+# ============================================================================
+CONFIG_ESP_TRACE_TRANSPORT_APPTRACE=y
+CONFIG_APPTRACE_DEST_JTAG=y
+CONFIG_APPTRACE_LOCK_ENABLE=y
+CONFIG_APPTRACE_ONPANIC_HOST_FLUSH_TMO=-1
+CONFIG_APPTRACE_POSTMORTEM_FLUSH_THRESH=0
+CONFIG_ESP_GCOV_ENABLE=y
+
+# GCOV needs __getreent() which currently newlib provides, and not picolibc
+CONFIG_LIBC_NEWLIB=y
+
+# ============================================================================
+# FreeRTOS Coverage Instrumentation
+# ============================================================================
+# Enable code coverage instrumentation for FreeRTOS kernel, port, and ESP additions
+CONFIG_FREERTOS_ENABLE_COVERAGE_TESTS=y
+
+# ============================================================================
+# Compiler Optimizations (Debug mode for maximum coverage)
+# ============================================================================
+# Use debug optimizations to prevent code elimination
+CONFIG_COMPILER_OPTIMIZATION_DEBUG=y
+# Keep assertions enabled to test error paths
+CONFIG_COMPILER_OPTIMIZATION_ASSERTIONS_ENABLE=y
+
+# Bootloader should use size optimization to keep bootloader size small
+CONFIG_BOOTLOADER_COMPILER_OPTIMIZATION_SIZE=y
+
+# ============================================================================
+# FreeRTOS Kernel Options (from sdkconfig.ci.freertos_options)
+# ============================================================================
+# Core timer selection
+CONFIG_FREERTOS_CORETIMER_1=y
+CONFIG_FREERTOS_OPTIMIZED_SCHEDULER=n
+
+# Stack overflow checking
+CONFIG_FREERTOS_CHECK_STACKOVERFLOW_PTRVAL=y
+CONFIG_FREERTOS_WATCHPOINT_END_OF_STACK=y
+
+# Interrupt backtrace
+CONFIG_FREERTOS_INTERRUPT_BACKTRACE=y
+
+# Static allocation support
+CONFIG_FREERTOS_SUPPORT_STATIC_ALLOCATION=y
+
+# Task pre-deletion hook
+CONFIG_FREERTOS_TASK_PRE_DELETION_HOOK=y
+
+# Queue registry
+CONFIG_FREERTOS_QUEUE_REGISTRY_SIZE=10
+
+# Trace facility and stats
+CONFIG_FREERTOS_USE_TRACE_FACILITY=y
+CONFIG_FREERTOS_USE_STATS_FORMATTING_FUNCTIONS=y
+CONFIG_FREERTOS_VTASKLIST_INCLUDE_COREID=y
+CONFIG_FREERTOS_GENERATE_RUN_TIME_STATS=y
+CONFIG_FREERTOS_RUN_TIME_COUNTER_TYPE_U64=y
+
+# FreeRTOS in IRAM
+CONFIG_FREERTOS_IN_IRAM=y
+
+# FPU in ISR
+CONFIG_FREERTOS_FPU_IN_ISR=y
+
+# Task notifications
+CONFIG_FREERTOS_TASK_NOTIFICATION_ARRAY_ENTRIES=2
+
+# List data integrity checks
+CONFIG_FREERTOS_USE_LIST_DATA_INTEGRITY_CHECK_BYTES=y
+
+# Timer task affinity
+CONFIG_FREERTOS_TIMER_TASK_AFFINITY_CPU1=y
+
+# Tick hook - enables vApplicationTickHook()
+CONFIG_FREERTOS_USE_TICK_HOOK=y
+
+# Idle hook - enables vApplicationIdleHook()
+CONFIG_FREERTOS_USE_IDLE_HOOK=y
+
+# Application task tag
+CONFIG_FREERTOS_USE_APPLICATION_TASK_TAG=y
+
+# ============================================================================
+# FreeRTOS Port Options
+# ============================================================================
+# Task function wrapper
+CONFIG_FREERTOS_TASK_FUNCTION_WRAPPER=y
+
+# Thread local storage deletion callbacks
+CONFIG_FREERTOS_TLSP_DELETION_CALLBACKS=y
+
+# Mutex owner check
+CONFIG_FREERTOS_CHECK_MUTEX_GIVEN_BY_OWNER=y
+
+# Port critical compliance check
+CONFIG_FREERTOS_CHECK_PORT_CRITICAL_COMPLIANCE=y