[FEATURE] Migrate SOF Unit Tests from CMock to Zephyr ztest Framework

[tmleman]

Feature Request

Problem Description

The current SOF unit test infrastructure uses CMock/CMocka framework, which creates problems:

1. Framework Mismatch: SOF is transitioning to Zephyr RTOS, but unit tests still use CMock instead of Zephyr's native testing framework
2. Integration Challenges: CMock tests don't integrate well with Zephyr's development workflow and Twister test runner
3. Platform Fragmentation: 15 different platform configurations with varying test counts (48-56 tests)
4. Developer Experience: Context-switching between different testing frameworks

Proposed Solution

Migrate all 56 existing CMock-based unit tests to Zephyr's native ztest framework:

Goals:

• Complete framework migration from CMock to ztest
• Unified testing experience aligned with Zephyr ecosystem
• Enhanced CI/CD integration with Twister test runner
• Maintain functional equivalence of all existing tests

Key Features:

• All 56 tests migrated (18 audio components, 10 library functions, 28 mathematical functions)
• Platform consistency across all 15 configurations
• Split architecture: basic unit tests (native_sim only) vs integration tests (multi-platform)

Current State

• 56 tests across 15 platform configurations using CMock
• Proof of Concept: Working ztest implementation in development branch (not yet integrated)

Platform Configurations

Platform Configuration	Test Count	Primary Target
unit_test_defconfig	56 tests	Generic UT framework
acp_6_3_defconfig	50 tests	AMD ACP 6.3
acp_7_0_defconfig	50 tests	AMD ACP 7.0
imx8_defconfig	48 tests	NXP i.MX8
imx8m_defconfig	48 tests	NXP i.MX8M
imx8ulp_defconfig	48 tests	NXP i.MX8ULP
imx8x_defconfig	48 tests	NXP i.MX8X
mt8186_defconfig	48 tests	MediaTek MT8186
mt8188_defconfig	48 tests	MediaTek MT8188
mt8195_defconfig	48 tests	MediaTek MT8195
mt8196_defconfig	48 tests	MediaTek MT8196
mt8365_defconfig	48 tests	MediaTek MT8365
rembrandt_defconfig	48 tests	AMD Rembrandt
renoir_defconfig	48 tests	AMD Renoir
vangogh_defconfig	48 tests	AMD Van Gogh

Note: All platform configurations are built in CI using native host compilers (not cross-compilation). The tests executed across different platform configurations are largely identical, with minimal platform-specific differences. This results in significant redundancy in CI builds, where the same test logic is compiled and executed multiple times with only minor configuration variations. The proposed ztest architecture aims to eliminate this redundancy by distinguishing between basic unit tests (native_sim only) and platform-specific integration tests.

Complete Test Migration Status

Audio Components (18 tests)

Test Name	Status	PR Link	Notes
buffer_copy	⏳ Pending	-	Buffer management
buffer_new	⏳ Pending	-	Buffer creation
buffer_wrap	⏳ Pending	-	Buffer wrapping
buffer_write	⏳ Pending	-	Buffer write operations
comp_set_state	⏳ Pending	-	Component state management
pcm_float_generic	⏳ Pending	-	PCM format conversion
mixer	⏳ Pending	-	Audio mixing
pipeline_new	⏳ Pending	-	Pipeline creation
pipeline_connect_upstream	⏳ Pending	-	Pipeline connection
pipeline_free	⏳ Pending	-	Pipeline cleanup
volume_process	⏳ Pending	-	Volume processing
mux_get_processing_function	⏳ Pending	-	MUX function selection
mux_copy	⏳ Pending	-	MUX copy operations
demux_copy	⏳ Pending	-	DEMUX copy operations
selector_test	⏳ Pending	-	Channel selector
eq_iir_process	⏳ Pending	-	IIR equalizer
eq_fir_process	⏳ Pending	-	FIR equalizer
drc_math_test	⏳ Pending	-	Dynamic range compression

Library Functions (10 tests)

Test Name	Status	PR Link	Notes
rstrcmp	❌ Blocked	Comment	String comparison
rstrlen	❌ Blocked	Comment	String length
fast-get-tests	✅ Complete	#10136	Fast getter functions
list_init	✅ Complete	#10066	List initialization (PoC exists)
list_is_empty	✅ Complete	#10066	List empty check (PoC exists)
list_item_append	✅ Complete	#10066	List append (PoC exists)
list_item_del	✅ Complete	#10066	List deletion (PoC exists)
list_item_is_last	✅ Complete	#10066	List last item check (PoC exists)
list_item_prepend	✅ Complete	#10066	List prepend (PoC exists)
list_item	✅ Complete	#10066	List item operations (PoC exists)

Mathematical Functions (28 tests)

Arithmetic Functions (6 tests)

Test Name	Status	PR Link	Notes
gcd	✅ Complete	#10138	Greatest common divisor
ceil_divide	✅ Complete	#10138	Ceiling division
find_equal_int16	✅ Complete	#10138	Find equal int16 values
find_min_int16	✅ Complete	#10138	Find minimum int16
find_max_abs_int32	✅ Complete	#10138	Find max absolute int32
norm_int32	✅ Complete	#10138	Normalize int32

Trigonometry Functions (9 tests)

Test Name	Status	PR Link	Notes
sin_32b_fixed	✅ Complete	#10233	32-bit fixed sine
cos_32b_fixed	✅ Complete	#10233	32-bit fixed cosine
sin_16b_fixed	✅ Complete	#10233	16-bit fixed sine
cos_16b_fixed	✅ Complete	#10233	16-bit fixed cosine
asin_32b_fixed	✅ Complete	#10233	32-bit fixed arcsine
acos_32b_fixed	✅ Complete	#10233	32-bit fixed arccosine
asin_16b_fixed	✅ Complete	#10233	16-bit fixed arcsine
acos_16b_fixed	✅ Complete	#10233	16-bit fixed arccosine
lut_sin_16b_fixed	✅ Complete	#10233	16-bit sine lookup table

Advanced Math Functions (6 tests)

Test Name	Status	PR Link	Notes
scalar_power	🔄 In Progress	10364	Scalar power operations
base2_logarithm	⏳ Pending	-	Base-2 logarithm
exponential	⏳ Pending	-	Exponential function
square_root	⏳ Pending	-	Square root
base_10_logarithm	⏳ Pending	-	Base-10 logarithm
base_e_logarithm	⏳ Pending	-	Natural logarithm

Audio Processing Math (7 tests)

Test Name	Status	PR Link	Notes
a_law_codec	⏳ Pending	-	A-law codec
mu_law_codec	⏳ Pending	-	Mu-law codec
fft	⏳ Pending	-	Fast Fourier Transform
window	⏳ Pending	-	Window functions
matrix	⏳ Pending	-	Matrix operations
auditory	⏳ Pending	-	Auditory processing
dct	⏳ Pending	-	Discrete Cosine Transform

Status Legend:

• ⏳ Pending: Not yet started
• 🟡 PoC Ready: Proof of concept exists, ready for integration
• 🔄 In Progress: Currently being migrated
• ✅ Complete: Migration completed and merged
• ❌ Blocked: Migration blocked by dependencies

Implementation Plan

Phase-Based Approach

Phase	Scope	Key Deliverables
Phase 1	PoC Integration	Merge PoC to main, establish dual architecture
Phase 2	Basic Unit Tests	Math, string, library functions (native_sim only)
Phase 3	Advanced Unit Tests	Complex math, audio processing math (native_sim only)
Phase 4	Integration Tests	Pipeline, modules, audio components (multi-platform)

Test Architecture

1. Basic Unit Tests (sof/test/ztest/unit/)

   • Platform: native_sim only
   • Scope: Mathematical functions, basic library functions
   • Execution: Fast, isolated testing

2. Integration Tests (sof/test/ztest/integration/)

   • Platform: native_sim in CI, with additional platforms enabled as needed (subset of current 15 configurations)
   • Scope: Pipeline management, audio modules, component interaction
   • Execution: Complex scenarios, real-world use cases

Migration Approach:

• All tests will initially be ported to run on native_sim platform and executed in CI
• Complex tests identified during migration will additionally be enabled on other platforms, requiring collaboration with specific platform developers
• CI Impact: No change to current CI behavior - tests will continue to run natively on the host, maintaining the same execution model as today's CMock tests
• Platform-specific work: Only complex integration tests will require platform maintainer involvement for multi-platform validation

Success Criteria

• 100% test migration completion (56/56 tests)
• Zero regression in test coverage or functionality

Benefits

• Unified testing framework aligned with SOF's Zephyr transition
• Improved developer productivity and reduced context switching
• Enhanced CI/CD integration through Twister test runner
• Future-proof testing infrastructure

[tmleman]

@lgirdwood topic for discussion: At what point can we start removing tests that have already been ported?

[tmleman]

Skipping migration of rstrcmp and rstrlen tests for now. In Zephyr builds, these functions are just simple wrappers around standard C library functions (strlen and strcmp), so the tests wouldn't be validating our custom implementations. The original unit tests were designed to test the custom implementations in sof/src/lib/lib.c which are only used in non-Zephyr builds, making these tests redundant in our primary target environment.

[tmleman]

Math Tests Migration Strategy

Current CMock Structure Analysis

The math tests are organized into 8 subcategories with clear separation:

sof/test/cmocka/src/math/
├── arithmetic/     # Codecs & Advanced Math (6 tests)
├── numbers/        # Basic Arithmetic (6 tests)
├── trig/           # Trigonometry (9 tests)
├── fft/            # FFT (1 test)
├── window/         # Window Functions (1 test)
├── matrix/         # Matrix Operations (1 test)
├── auditory/       # Auditory Processing (1 test)
└── dct/            # DCT (1 test)

Proposed Ztest Directory Structure

Based on the logical grouping and complexity analysis, the following structure is proposed:

sof/test/ztest/unit/math/
├── basic/                          # Simple, fast unit tests
│   ├── arithmetic/                 # Basic number operations (6 tests)
│   │   ├── test_gcd_ztest.c
│   │   ├── test_ceil_divide_ztest.c
│   │   ├── test_find_equal_int16_ztest.c
│   │   ├── test_find_min_int16_ztest.c
│   │   ├── test_find_max_abs_int32_ztest.c
│   │   ├── test_norm_int32_ztest.c
│   │   ├── CMakeLists.txt
│   │   ├── testcase.yaml
│   │   └── prj.conf
│   └── trigonometry/               # Trig functions (9 tests)
│       ├── test_sin_32b_fixed_ztest.c
│       ├── test_cos_32b_fixed_ztest.c
│       ├── test_sin_16b_fixed_ztest.c
│       ├── test_cos_16b_fixed_ztest.c
│       ├── test_asin_32b_fixed_ztest.c
│       ├── test_acos_32b_fixed_ztest.c
│       ├── test_asin_16b_fixed_ztest.c
│       ├── test_acos_16b_fixed_ztest.c
│       ├── test_lut_sin_16b_fixed_ztest.c
│       ├── CMakeLists.txt
│       ├── testcase.yaml
│       └── prj.conf
├── advanced/                       # Complex mathematical operations
│   ├── functions/                  # Advanced math functions (6 tests)
│   │   ├── test_scalar_power_ztest.c
│   │   ├── test_base2_logarithm_ztest.c
│   │   ├── test_exponential_ztest.c
│   │   ├── test_square_root_ztest.c
│   │   ├── test_base_10_logarithm_ztest.c
│   │   ├── test_base_e_logarithm_ztest.c
│   │   ├── CMakeLists.txt
│   │   ├── testcase.yaml
│   │   └── prj.conf
│   └── codecs/                     # Audio codec functions (2 tests)
│       ├── test_a_law_codec_ztest.c
│       ├── test_mu_law_codec_ztest.c
│       ├── CMakeLists.txt
│       ├── testcase.yaml
│       └── prj.conf
└── dsp/                           # Digital Signal Processing (5 tests)
    ├── transforms/                # FFT, DCT (2 tests)
    │   ├── test_fft_ztest.c
    │   ├── test_dct_ztest.c
    │   ├── CMakeLists.txt
    │   ├── testcase.yaml
    │   └── prj.conf
    ├── processing/                # Window, Matrix, Auditory (3 tests)
    │   ├── test_window_ztest.c
    │   ├── test_matrix_ztest.c
    │   ├── test_auditory_ztest.c
    │   ├── CMakeLists.txt
    │   ├── testcase.yaml
    │   └── prj.conf
    └── shared/                    # Common DSP test utilities
        ├── math_test_data.h       # Shared test vectors
        └── dsp_test_utils.h       # Common DSP test functions

Migration Phases

Phase 2A: Basic Math Functions (12 tests)

• Priority: High (foundation for other math tests)
• Target Platform: native_sim only
• Complexity: Low - simple numerical operations
• Dependencies: Minimal SOF dependencies

math/basic/arithmetic/     (6 tests)
math/basic/trigonometry/   (9 tests)

Phase 2B: Advanced Math Functions (8 tests)

• Priority: Medium
• Target Platform: native_sim only
• Complexity: Medium - more complex algorithms
• Dependencies: SOF math libraries

math/advanced/functions/   (6 tests)
math/advanced/codecs/      (2 tests)

Phase 2C: DSP Functions (8 tests)

• Priority: Medium-High (used by audio components)
• Target Platform: native_sim primarily, may need additional platforms
• Complexity: High - complex algorithms with reference data
• Dependencies: SOF DSP libraries, test reference data

math/dsp/transforms/       (2 tests)
math/dsp/processing/       (3 tests)

[tmleman]

To be done after the migration is completed:

• Refactor functions in sof/src/math/numbers.c: constants as function arguments + update documentation

[lgirdwood]

@tmleman fyi - the test bench will still run the modules and infra on host meaning we will still have the valgrind testing available for most code.

[tmleman]

@lgirdwood - First PR submitted for legacy test cleanup #10367

Removes legacy cmocka tests for list and fast-get components after coverage verification:

• List: 25/25 lines (ztest) vs 22/22 lines (legacy) + function tracking
• Fast-get: 70/76 lines + 5 functions (ztest) vs 69/72 lines + 3 functions (legacy)

No regression detected. All removed tests have equivalent ztest implementations with identical test logic.