TEST: Refactor NetCDF tests to be more pytest friendly

.azure-pipelines/windows.yml

@@ -80,6 +80,7 @@ jobs:
           -I test_minc2 ^
           -I test_minc2_data ^
           -I test_mriutils ^
+          -I test_netcdf ^
           -I test_nibabel_data ^
           -I test_nifti1 ^
           -I test_nifti2 ^

.travis.yml

@@ -173,6 +173,7 @@ script:
                 -I test_minc2 \
                 -I test_minc2_data \
                 -I test_mriutils \
+                -I test_netcdf \
                 -I test_nibabel_data \
                 -I test_nifti1 \
                 -I test_nifti2 \

nibabel/externals/tests/test_netcdf.py

@@ -2,20 +2,15 @@
 
 import os
 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_
 
-from ..netcdf import netcdf_file
+import pytest
 
-from nose.tools import assert_true, assert_false, assert_equal, assert_raises
+from ..netcdf import netcdf_file
 
 TEST_DATA_PATH = pjoin(dirname(__file__), 'data')
 
@@ -36,54 +31,41 @@ def make_simple(*args, **kwargs):
     f.close()
 
 
-def gen_for_simple(ncfileobj):
-    ''' Generator for example fileobj tests '''
-    yield assert_equal, ncfileobj.history, b'Created for a test'
+def assert_simple_truths(ncfileobj):
+    assert ncfileobj.history == b'Created for a test'
     time = ncfileobj.variables['time']
-    yield assert_equal, time.units, b'days since 2008-01-01'
-    yield assert_equal, time.shape, (N_EG_ELS,)
-    yield assert_equal, time[-1], N_EG_ELS-1
-
-
-def test_read_write_files():
-    # test round trip for example file
-    cwd = os.getcwd()
-    try:
-        tmpdir = tempfile.mkdtemp()
-        os.chdir(tmpdir)
-        with make_simple('simple.nc', 'w') as f:
-            pass
-        # To read the NetCDF file we just created::
-        with netcdf_file('simple.nc') as f:
-            # Using mmap is the default
-            yield assert_true, f.use_mmap
-            for testargs in gen_for_simple(f):
-                yield testargs
-
-        # Now without mmap
-        with netcdf_file('simple.nc', mmap=False) as f:
-            # Using mmap is the default
-            yield assert_false, f.use_mmap
-            for testargs in gen_for_simple(f):
-                yield testargs
-
-        # To read the NetCDF file we just created, as file object, no
-        # mmap.  When n * n_bytes(var_type) is not divisible by 4, this
-        # raised an error in pupynere 1.0.12 and scipy rev 5893, because
-        # calculated vsize was rounding up in units of 4 - see
-        # https://www.unidata.ucar.edu/software/netcdf/docs/netcdf.html
-        fobj = open('simple.nc', 'rb')
-        with netcdf_file(fobj) as f:
-            # by default, don't use mmap for file-like
-            yield assert_false, f.use_mmap
-            for testargs in gen_for_simple(f):
-                yield testargs
-    except:
-        os.chdir(cwd)
-        shutil.rmtree(tmpdir)
-        raise
-    os.chdir(cwd)
-    shutil.rmtree(tmpdir)
+    assert time.units == b'days since 2008-01-01'
+    assert time.shape == (N_EG_ELS,)
+    assert time[-1] == N_EG_ELS - 1
+
+
+def test_read_write_files(tmp_path):
+    fname = str(tmp_path / 'simple.nc')
+
+    with make_simple(fname, 'w') as f:
+        pass
+    # To read the NetCDF file we just created::
+    with netcdf_file(fname) as f:
+        # Using mmap is the default
+        assert f.use_mmap
+        assert_simple_truths(f)
+
+    # Now without mmap
+    with netcdf_file(fname, mmap=False) as f:
+        # Using mmap is the default
+        assert not f.use_mmap
+        assert_simple_truths(f)
+
+    # To read the NetCDF file we just created, as file object, no
+    # mmap.  When n * n_bytes(var_type) is not divisible by 4, this
+    # raised an error in pupynere 1.0.12 and scipy rev 5893, because
+    # calculated vsize was rounding up in units of 4 - see
+    # https://www.unidata.ucar.edu/software/netcdf/docs/netcdf.html
+    fobj = open(fname, 'rb')
+    with netcdf_file(fobj) as f:
+        # by default, don't use mmap for file-like
+        assert not f.use_mmap
+        assert_simple_truths(f)
 
 
 def test_read_write_sio():
@@ -93,28 +75,26 @@ def test_read_write_sio():
 
     eg_sio2 = BytesIO(str_val)
     with netcdf_file(eg_sio2) as f2:
-        for testargs in gen_for_simple(f2):
-            yield testargs
+        assert_simple_truths(f2)
 
     # Test that error is raised if attempting mmap for sio
     eg_sio3 = BytesIO(str_val)
-    yield assert_raises, ValueError, netcdf_file, eg_sio3, 'r', True
+    with pytest.raises(ValueError):
+        netcdf_file(eg_sio3, 'r', True)
     # Test 64-bit offset write / read
     eg_sio_64 = BytesIO()
     with make_simple(eg_sio_64, 'w', version=2) as f_64:
         str_val = eg_sio_64.getvalue()
 
     eg_sio_64 = BytesIO(str_val)
     with netcdf_file(eg_sio_64) as f_64:
-        for testargs in gen_for_simple(f_64):
-            yield testargs
-        yield assert_equal, f_64.version_byte, 2
+        assert_simple_truths(f_64)
+        assert f_64.version_byte == 2
     # also when version 2 explicitly specified
     eg_sio_64 = BytesIO(str_val)
     with netcdf_file(eg_sio_64, version=2) as f_64:
-        for testargs in gen_for_simple(f_64):
-            yield testargs
-        yield assert_equal, f_64.version_byte, 2
+        assert_simple_truths(f_64)
+        assert f_64.version_byte == 2
 
 
 def test_read_example_data():
@@ -134,7 +114,8 @@ def test_itemset_no_segfault_on_readonly():
         time_var = f.variables['time']
 
     # time_var.assignValue(42) should raise a RuntimeError--not seg. fault!
-    assert_raises(RuntimeError, time_var.assignValue, 42)
+    with pytest.raises(RuntimeError):
+        time_var.assignValue(42)
 
 
 def test_write_invalid_dtype():
@@ -147,22 +128,22 @@ def test_write_invalid_dtype():
     with netcdf_file(BytesIO(), 'w') as f:
         f.createDimension('time', N_EG_ELS)
         for dt in dtypes:
-            yield assert_raises, ValueError, \
-                f.createVariable, 'time', dt, ('time',)
+            with pytest.raises(ValueError):
+                f.createVariable('time', dt, ('time',))
 
 
 def test_flush_rewind():
     stream = BytesIO()
     with make_simple(stream, mode='w') as f:
-        x = f.createDimension('x',4)
+        x = f.createDimension('x', 4)
         v = f.createVariable('v', 'i2', ['x'])
         v[:] = 1
         f.flush()
         len_single = len(stream.getvalue())
         f.flush()
         len_double = len(stream.getvalue())
 
-    assert_(len_single == len_double)
+    assert len_single == len_double
 
 
 def test_dtype_specifiers():
@@ -192,8 +173,8 @@ def test_ticket_1720():
 
     io = BytesIO(contents)
     with netcdf_file(io, 'r') as f:
-        assert_equal(f.history, b'Created for a test')
+        assert f.history == b'Created for a test'
         float_var = f.variables['float_var']
-        assert_equal(float_var.units, b'metres')
-        assert_equal(float_var.shape, (10,))
-        assert_(np.allclose(float_var[:], items))
+        assert float_var.units == b'metres'
+        assert float_var.shape == (10,)
+        assert np.allclose(float_var[:], items)