Understanding the Basics: Unity and CMock
Before diving into troubleshooting, being aware of how Unity and CMock work together is crucial. Unity is a test framework, while CMock generates mock functions to simulate interactions with physical devices or complex modules not available during testing. They are often used in tandem for unit testing in embedded systems. Knowing the workflow and typical pitfalls helps identify integration issues faster.
Common Integration Problems
Problems often arise from misconfigurations, incorrect mock generation, or linking issues. Here are some common problems and how to troubleshoot them:
- Incorrect Linkage Between Headers and Mocks:
- Ensure your mock files match the function prototypes declared in the headers. Check for discrepancies in the header files that may cause CMock to generate incorrect mocks.
- If a mock file isn't being generated, make sure the header is included in the list of files to mock in your
CMockConfig.yml.
:cmock:
:mock_path: 'mocks'
:plugins:
- :callback
:treat_as:
int: [ 'int8_t', 'int16_t', 'int32_t' ]
:includes:
- 'header_to_mock.h'
Build Failures or Linker Errors:
These can arise from missing dependencies or incorrect mock configurations. Verify that the build system (e.g., Makefile) correctly references Unity and CMock libraries and that mock files are generated prior to compiling the tests.
If using GCC, you can check for unresolved symbols with appropriate linker flags like -Wl,--trace-symbol.
Mock Generation Issues:
Make sure CMock is generating mocks for all necessary functions. Adjust the :includes section in CMockConfig.yml if certain functions are ignored or improperly configured.
Verify that your CMock version supports all features required by your mocking requirements.
- Version Mismatch:
- Ensure the versions of Unity, CMock, and any other dependencies are compatible. Checking release notes or changelogs can help identify incompatible changes or necessary updates.
Advanced Troubleshooting
Verbose Logs:
Increase the verbosity of your build system to see detailed log messages. This helps track down where the process breaks between generating mocks and running tests.
Mock Customization and Plugins:
Use CMock plugins for more control over the mock behavior. For instance, the following plugin can add callbacks to your mocks for advanced test scenarios:
:plugins:
- :callback
Test Simplification:
Reduce your test complexity by isolating issues; focus on a small subset of tests that always fail instead of the entire test suite.
Scripted Scripts:
Use a script to manage the processes of generating mocks, compiling them, and executing tests. Automating the salvage process minimizes human-induced errors and saves time.
- Checking Dependency and Path Configurations:
- Scrutinize the paths used by your tooling, especially as they designate where to find source files, headers, and the mock definitions.
INC_DIRS := -I$(UNITY_DIR)/src -I$(CMOCK_DIR)/src
SRC_FILES := $(UNITY_DIR)/src/unity.c
- File Permissions and Encoding:
- Occasionally, file encoding and permissions can interfere with Unity/CMock operations. Ensure source files use the correct encoding and accessible permissions.
Conclusion
The effective use of CMock with Unity involves assuring all configurations align with your project’s requirements and anticipating integration issues. Documentation, community discussions, and robust configuration management all contribute to balanced integration. With these insights, tackle complex unit tests with streamlined embedded software mock setups, ensuring high-quality firmware development.
