Only test MPI if installed

Author: matteobachetti

hendrics/parallel.py

@@ -2,7 +2,6 @@
 from multiprocessing import Pool
 
 import numpy as np
-from mpi4py import MPI
 from stingray import AveragedPowerspectrum, EventList
 from stingray.fourier import positive_fft_bins
 from stingray.gti import time_intervals_from_gtis
@@ -169,6 +168,8 @@ def main_mpi(fname, sample_time, segment_size):
       and dependencies are available.
     - Only the rank responsible for the final reduction returns the results; other ranks return None.
     """
+    from mpi4py import MPI
+
     tsreader = FITSTimeseriesReader(fname, output_class=EventList)
 
     def data_lookup():

hendrics/tests/test_parallel.py

@@ -1,3 +1,4 @@
+import importlib
 import subprocess as sp
 import tempfile
 
@@ -8,6 +9,12 @@
 from hendrics.fake import main as main_fake
 from hendrics.parallel import main as main_parallel
 
+HAS_MPI = importlib.util.find_spec("mpi4py") is not None
+
+test_cases = ["none", "multiprocessing"]
+if HAS_MPI:
+    test_cases.append("mpi")
+
 
 class TestParallel:
     def setup_class(cls):
@@ -21,7 +28,7 @@ def setup_class(cls):
             cls.events, dt=0.1, segment_size=10.0, use_common_mean=False, norm="leahy"
         )
 
-    @pytest.mark.parametrize("method", ["none", "multiprocessing", "mpi"])
+    @pytest.mark.parametrize("method", test_cases)
     @pytest.mark.parametrize("norm", ["leahy", "frac", "abs"])
     def test_parallel_versions(self, method, norm):
         out_file = tempfile.NamedTemporaryFile(suffix=".hdf5", delete=False)

pyproject.toml

@@ -58,6 +58,7 @@ test_all = [
     "numba",
     "netcdf4==1.7.0",
     "scikit-image",
+    "mpi4py",
 ]
 recommended = [
     "numba",
@@ -72,6 +73,7 @@ all = [
     "imageio",
     "netcdf4==1.7.0",
     "scikit-image",
+    "mpi4py",
 ]
 docs = [
     "tomli>=1.1.0; python_version < '3.11'",