Test the qiskit-addon-sqd entry points, serially and under MPI

pyproject.toml

@@ -37,6 +37,12 @@ basetest = [
 test = [
     "sbd-eigensolver[basetest]",
     "pytest-mpi>=0.6",
+    # The SQD integration tests drive qiskit-addon-sqd's own entry point, and read the
+    # reference Hamiltonian from a FCIDUMP with pyscf. Both are in the default test
+    # extra rather than an opt-in one so that `tox -e py` and `tox -e mpi` cover that
+    # path; the tests skip themselves if the imports are unavailable anyway.
+    "qiskit-addon-sqd>=0.13.1",
+    "pyscf>=2.9",
 ]
 nbtest = [
     "sbd-eigensolver[basetest]",

test/conftest.py

@@ -24,6 +24,12 @@
 # initialized, so tests that need it are skipped rather than failing.
 DATA_DIR = Path(__file__).resolve().parents[1] / "vendor" / "sbd-upstream" / "data"
 
+# The curated h2o counts shipped with the examples. Unlike the reference data above this
+# is part of the repository proper, so it is always present.
+COUNTS_PATH = (
+    Path(__file__).resolve().parents[1] / "python" / "examples" / "count_dict_h2o.json"
+)
+
 
 # Slow tests are opt-in through a command-line flag rather than excluded by default,
 # so that they are reported as skipped with a reason instead of silently deselected.
@@ -77,19 +83,55 @@ def pytest_report_header():
     return f"sbd {sbd.__version__}: backends built {available}, testing {requested}"
 
 
-@pytest.fixture(scope="session")
-def backend():
-    """The SBD backend to test, honoring SBD_TEST_DEVICE if it is set.
+def _requested_device() -> str | None:
+    """``SBD_TEST_DEVICE``, or ``None`` to mean whatever the build defaults to.
 
-    A backend named in ``SBD_TEST_DEVICE`` that was not compiled into this build is
-    reported as a skip, since which backends exist depends on how the package was
-    built. That a backend is missing is a fact about the build; that ``sbd`` itself is
-    missing is a failure, and is left to raise.
+    A backend named there but not compiled into this build is reported as a skip, since
+    which backends exist depends on how the package was built. That a backend is missing
+    is a fact about the build; that ``sbd`` itself is missing is a failure, and is left
+    to raise.
     """
     import sbd
 
     device = os.environ.get("SBD_TEST_DEVICE")
     available = sbd.available_backends()
     if device is not None and device not in available:
         pytest.skip(f"backend {device!r} was not built; available: {available}")
-    return sbd.get_backend(device)
+    return device
+
+
+@pytest.fixture(scope="session")
+def backend():
+    """The SBD backend module to test, for tests calling the extension directly."""
+    import sbd
+
+    return sbd.get_backend(_requested_device())
+
+
+@pytest.fixture(scope="session")
+def device_config():
+    """The same selection as ``backend``, in the form the solver wrappers take.
+
+    ``solve_sci`` and ``solve_sci_batch`` accept a ``DeviceConfig`` rather than a backend
+    module -- they resolve the module themselves from its ``device`` key -- so the two
+    fixtures exist to hand each layer the type it expects, off one shared setting.
+
+    ``None`` when nothing is requested is deliberate: it leaves the wrapper's own backend
+    resolution in the path, which is what an ordinary caller gets.
+    """
+    from sbd.device_config import DeviceConfig
+
+    device = _requested_device()
+    if device is None:
+        return None
+    # The generic constructor accepts every device key, including hyphenated ones like
+    # 'gpu-omp' that do not correspond to a classmethod name.
+    return DeviceConfig(device=device)
+
+
+@pytest.fixture(scope="session")
+def counts_path() -> Path:
+    """Path to the curated h2o counts file used by the examples."""
+    if not COUNTS_PATH.is_file():
+        pytest.skip(f"counts file not found at {COUNTS_PATH}")
+    return COUNTS_PATH