TST: add regression test for scipygh-1550 (netcdf_file leaves mmaps o…

…pen).

scipy/io/tests/test_netcdf.py

@@ -5,14 +5,12 @@
 from os.path import join as pjoin, dirname
 import shutil
 import tempfile
-import time
-import sys
 from io import BytesIO
 from glob import glob
 from contextlib import contextmanager
 
 import numpy as np
-from numpy.testing import dec, assert_, assert_allclose
+from numpy.testing import assert_, assert_allclose
 
 from scipy.io.netcdf import netcdf_file
 
@@ -198,3 +196,14 @@ def test_ticket_1720():
         assert_equal(float_var.units, b'metres')
         assert_equal(float_var.shape, (10,))
         assert_allclose(float_var[:], items)
+
+
+def test_mmaps_closed():
+    # Regression test for gh-1550.  Will fail with "Too many open files"
+    # error if not all mmaps aren't closed by ``f.close()``.
+    filename = pjoin(TEST_DATA_PATH, 'example_1.nc')
+    vars = []
+    for i in range(1100):
+        f = netcdf_file(filename, mmap=True)
+        vars.append(f.variables['lat'])
+        f.close()