Add initial pytest test suite and wire it into CI

[Copilot]

KernelDB had no Python tests. This adds a pytest suite covering the core library features and hooks it into the existing CI pipeline.

Test structure

• tests/conftest.py – Environment detection (_hipcc_available, _gpu_available), a requires_rocm skip marker, inline HIP source snippets for five test scenarios, and session-scoped fixtures that compile each binary once via hipcc -g.
• tests/test_imports.py – Validates the public API contract: all symbols in __all__ are importable, __version__ is set, and key classes (KernelDB, Kernel, Instruction, BasicBlock, CDNAKernel, ArchDescriptor, HsaAgent, KernelArgument) are accessible.
• tests/test_kernels.py – Covers kernel discovery (get_kernels), source-line mapping, instruction extraction with attribute checks (disassembly, line, column, file_name), regex filtering semantics, basic block extraction, and the high-level Kernel wrapper properties (.lines, .assembly, .files, .signature).
• tests/test_arguments.py – Covers argument metadata (name, type, size, alignment), pointer/scalar sizes, Kernel.has_arguments(), nested struct member recursion (BoundingBox → Point3D), typedef preservation vs. resolution (resolve_typedefs=False/True), and template instantiation (scale_values<float> / scale_values<double>).

Configuration

pyproject.toml gains a [tool.pytest.ini_options] section (testpaths = ["tests"], -v).

CI gets a Run pytest step that runs pytest tests/ -v inside the Apptainer container after the editable install:

- name: Run pytest
  run: |
    bash .github/scripts/container_exec.sh "
      pip install -e '.[dev]'
      pytest tests/ -v
    "

All GPU-dependent tests skip automatically via @requires_rocm when hipcc or an HSA agent is not present; all test modules skip cleanly when the C++ extension is not compiled.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Add unittests to CI</issue_title>
<issue_description>We just added CI to KernelDB and we would like to add some unittests to exercise the different features of KernelDB. Please add some initial set of tests and lets focus on Python tests only using pytest for now.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Add unittests to CI #22

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