Add test of results round trip when using MPI.

tests/mpi_test.py

@@ -237,6 +237,18 @@ def do_mpi_cov(comm, method, output=True):
         print(comm.rank, "Running RR process")
     rr.process(ran_cat, comm=comm)
 
+    gg_save_file = os.path.join('data','mpi_gg_save.fits')
+    ng_save_file = os.path.join('data','mpi_ng_save.fits')
+    nn_save_file = os.path.join('data','mpi_nn_save.fits')
+    rr_save_file = os.path.join('data','mpi_rr_save.fits')
+    if comm.rank == 0:
+        if output:
+            print(comm.rank, "Writing to save files")
+        gg.write(gg_save_file, write_patch_results=True)
+        ng.write(ng_save_file, write_patch_results=True)
+        nn.write(nn_save_file, write_patch_results=True)
+        rr.write(rr_save_file, write_patch_results=True)
+
     # Only the root process gets the complete version
     # when you call the above with comm
     if output:
@@ -324,6 +336,26 @@ def do_mpi_cov(comm, method, output=True):
     np.testing.assert_allclose(A1b, A2b, atol=tol)
     np.testing.assert_allclose(w1b, w2b, atol=tol)
 
+    # Finally, read back in from the save file and redo the covariance.
+    rng = np.random.RandomState(31415)
+    gg = treecorr.GGCorrelation(bin_size=0.3, min_sep=10., max_sep=50., rng=rng)
+    ng = treecorr.NGCorrelation(bin_size=0.3, min_sep=10., max_sep=50., rng=rng)
+    nn = treecorr.NNCorrelation(bin_size=0.3, min_sep=10., max_sep=50., rng=rng)
+    rr = treecorr.NNCorrelation(bin_size=0.3, min_sep=10., max_sep=50., rng=rng)
+    gg.read(gg_save_file)
+    ng.read(ng_save_file)
+    nn.read(nn_save_file)
+    rr.read(rr_save_file)
+
+    ng.calculateXi()
+    nn.calculateXi(rr=rr)
+    corrs = [gg, ng, nn]
+    cov3 = treecorr.estimate_multi_cov(corrs, method, comm=comm)
+    if output:
+        print("\nCOV 3\n", cov3[0:3,0:3], " for ", comm.rank, "\n")
+
+    np.testing.assert_allclose(cov1, cov3, atol=tol)
+
 
 if __name__ == '__main__':
     from mpi4py import MPI