# affine-py compatibility scope
The Python test suite contains 84 collected tests. Every test category is
accounted for, but Python runtime protocols are not reproduced in Rust.
| Constructors and rotation | Compatible | Constructor unit tests |
| Determinant, inversion, composition and round trips | Compatible | Core operation and invariant tests |
| Geometric properties | Planned for Phase 2 | Native Rust property tests |
| GDAL and Shapely coefficient ordering | Compatible | Conversion tests |
| World File parsing and serialization | Planned for Phase 2 | Parser and round-trip tests |
| Python argument count and dynamic type errors | Excluded | Rust compile-time type checking |
| Python indexing, slicing and operator fallback | Rust-native replacement | Named methods and selected traits |
| Invalid `g`, `h`, `i` matrix row | Excluded | The six-field type cannot represent it |
| NumPy protocol tests (7) | Excluded from core | Optional future ecosystem adapter |
| Pickle and multiprocessing tests (2) | Excluded | Outside the pure Rust crate boundary |
Before the first stable release this document must be expanded into a
test-by-test traceability table, with one disposition for every collected
pytest case.