A general mocked interface for the coupling library preCICE

Testing adapters for the preCICE coupling library requires full solver installations and complete coupling workflows, resulting in slow feedback cycles, brittle test environments, and high development overhead. This thesis presents a lightweight mock implementation of the preCICE Participant API that addresses these challenges through configuration parsing, deterministic data modes, and simulation of key lifecycle behaviors. The mock is implemented as a single C++ source file with minimal dependencies and integrated into existing preCICE build systems. The mock enables adapter testing in isolation without external solver dependencies, provides fully reproducible outputs through seeded pseudo-random data generation, and supports both explicit and implicit coupling schemes. Empirical validation demonstrates API compatibility with existing preCICE tutorials and training materials, deterministic behavior across repeated runs, and 2-5$\times$ performance improvements over full coupled simulations. By eliminating most external dependencies and enabling fast, deterministic test execution, the mock facilitates test-driven development practices and integration into continuous integration pipelines.