Success Story
Automated
Link Stubbing for
Faster Isolated
C++ Unit Tests
in TESSY
Customer/Partner:
Razorcat (TESSY)
Context
emmtrix completed a project for its long-standing partner Razorcat, the company behind TESSY, a widely used test automation tool in safety-critical and embedded software development.
While TESSY has long provided strong support for unit testing in C, creating isolated unit tests for C++ code was still associated with substantial manual effort. In particular, making individual or small sets of C/C++ source files linkable often required extensive hand-written stubs for missing functions, classes, and global variables.
Challenge
When unit testing isolated C/C++ files, linker errors occur when dependencies are missing. In C++, this problem is amplified by:
- Constructors and destructors
- Inheritance and virtual functions
- Templates and standard library types
- Complex object initialization semantics
This made C++ unit test creation significantly more time-consuming compared to C, limiting automation and slowing down test development.
Solution
On behalf of Razorcat, emmtrix developed the emmtrix Link Stubber, a Clang-based command-line tool that automatically generates stub implementations for unresolved C and C++ symbols.
The tool makes incomplete translation units linkable without requiring full implementations.
Implementation Highlights
- Integrated directly into TESSY
- Automated stub generation for C++ functions, classes, constructors, destructors, and globals
- Support for inheritance, abstract classes, and standard library types
- Seamless unit test creation for isolated C++ source files
- Reduced manual effort compared to hand-written stubs
Results
- Extended efficient unit test creation from C to modern C++
- Reduced setup time for isolated C++ unit tests
- Improved scalability and automation in C++ test workflows
- Lowered the barrier for testing legacy and complex C++ codebases
Partner Feedback
Razorcat highlighted that automated link stubbing reduces recurring manual effort when setting up isolated C++ unit tests and improves the scalability of the workflow.
“Integrating automated link stubbing reduces the manual work required to set up isolated C++ unit tests and makes the workflow more scalable.”
Closing
This project shows how compiler-based tooling can reduce setup effort in C++ unit testing workflows, including in safety-critical environments.
If you would like to discuss similar requirements in C++ unit testing, automated stub generation, or test workflow automation for embedded software, feel free to contact us via our contact form or get directly in touch.
Rainer Heim