dl tutorial files to tmp directory, then move them once successful (pydata#1393)

* dl tutorial files to tmp directory, then move them once successful

closes pydata#1392

* redo attempt at tutorial checking to use md5 checksums instead. depends on pydata/xarray-data#9

* rm extraneous import

* update md5 function name

* update whats-new.rst

* fix issue link in whats-new

* adding tutorial dataset test, adds conditional --run-network-tests flag to pytest cli

* one suppress block per file

Author: gidden

.travis.yml

@@ -23,7 +23,7 @@ matrix:
   - python: 3.6
     env:
     - CONDA_ENV=py36
-    - EXTRA_FLAGS="--run-flaky"
+    - EXTRA_FLAGS="--run-flaky --run-network-tests"
   - python: 3.6
     env: CONDA_ENV=py36-pydap
   - python: 3.6
@@ -45,7 +45,7 @@ matrix:
   - python: 3.6
     env:
     - CONDA_ENV=py36
-    - EXTRA_FLAGS="--run-flaky"
+    - EXTRA_FLAGS="--run-flaky --run-network-tests"
   - python: 3.6
     env: CONDA_ENV=py36-pydap
   - python: 3.6

conftest.py

@@ -5,3 +5,5 @@ def pytest_addoption(parser):
     """Add command-line flags for pytest."""
     parser.addoption("--run-flaky", action="store_true",
                      help="runs flaky tests")
+    parser.addoption("--run-network-tests", action="store_true",
+                     help="runs tests requiring a network connection")

doc/whats-new.rst

@@ -30,6 +30,11 @@ Enhancements
   By `Chun-Wei Yuan <https://github.com/chunweiyuan>`_ and
      `Kyle Heuton <https://github.com/kheuton>`_.
 
+- Enhanced tests suite by use of ``@network`` decorator, which is
+  controlled via ``--run-network-tests`` command line argument
+  to ``py.test`` (:issue:`1393`).
+  By `Matthew Gidden <https://github.com/gidden>`_.
+
 Bug fixes
 ~~~~~~~~~
 
@@ -40,6 +45,10 @@ By `Ryan Abernathey <https://github.com/rabernat>`_.
 ``data_vars``.
 By `Keisuke Fujii <https://github.com/fujiisoup>`_.
 
+- Tutorial datasets are now checked against a reference MD5 sum to confirm
+  successful download (:issue:`1392`). By `Matthew Gidden
+  <https://github.com/gidden>`_.
+
 .. _whats-new.0.9.5:
 
 v0.9.5 (17 April, 2017)

xarray/tests/__init__.py

@@ -100,14 +100,20 @@
 
 try:
     _SKIP_FLAKY = not pytest.config.getoption("--run-flaky")
+    _SKIP_NETWORK_TESTS = not pytest.config.getoption("--run-network-tests")
 except ValueError:
     # Can't get config from pytest, e.g., because xarray is installed instead
     # of being run from a development version (and hence conftests.py is not
     # available). Don't run flaky tests.
     _SKIP_FLAKY = True
+    _SKIP_NETWORK_TESTS = True
 
 flaky = pytest.mark.skipif(
     _SKIP_FLAKY, reason="set --run-flaky option to run flaky tests")
+network = pytest.mark.skipif(
+    _SKIP_NETWORK_TESTS,
+    reason="set --run-network-tests option to run tests requiring an "
+    "internet connection")
 
 
 class TestCase(unittest.TestCase):
@@ -173,6 +179,7 @@ class UnexpectedDataAccess(Exception):
 
 
 class InaccessibleArray(utils.NDArrayMixin):
+
     def __init__(self, array):
         self.array = array
 
@@ -181,6 +188,7 @@ def __getitem__(self, key):
 
 
 class ReturnItem(object):
+
     def __getitem__(self, key):
         return key
 

xarray/tests/test_tutorial.py

@@ -1,23 +1,27 @@
 from __future__ import absolute_import
 from __future__ import division
 from __future__ import print_function
+
 import os
+import pytest
 
 from xarray import tutorial, DataArray
 from xarray.core.pycompat import suppress
 
-from . import TestCase, unittest
+from . import TestCase, network
 
 
-@unittest.skip('TODO: make this conditional on network availability')
-class Test_load_dataset(TestCase):
+@network
+class TestLoadDataset(TestCase):
 
     def setUp(self):
         self.testfile = 'tiny'
         self.testfilepath = os.path.expanduser(os.sep.join(
             ('~', '.xarray_tutorial_data', self.testfile)))
         with suppress(OSError):
-            os.remove(self.testfilepath)
+            os.remove('{}.nc'.format(self.testfilepath))
+        with suppress(OSError):
+            os.remove('{}.md5'.format(self.testfilepath))
 
     def test_download_from_github(self):
         ds = tutorial.load_dataset(self.testfile)

xarray/tutorial.py

@@ -9,6 +9,8 @@
 from __future__ import division
 from __future__ import print_function
 
+import hashlib
+
 import os as _os
 
 from .backends.api import open_dataset as _open_dataset
@@ -18,9 +20,17 @@
 _default_cache_dir = _os.sep.join(('~', '.xarray_tutorial_data'))
 
 
+def file_md5_checksum(fname):
+    hash_md5 = hashlib.md5()
+    with open(fname, "rb") as f:
+        hash_md5.update(f.read())
+    return hash_md5.hexdigest()
+
+
 # idea borrowed from Seaborn
 def load_dataset(name, cache=True, cache_dir=_default_cache_dir,
-                 github_url='https://github.com/pydata/xarray-data',  **kws):
+                 github_url='https://github.com/pydata/xarray-data',
+                 branch='master', **kws):
     """
     Load a dataset from the online repository (requires internet).
 
@@ -37,13 +47,17 @@ def load_dataset(name, cache=True, cache_dir=_default_cache_dir,
         If True, then cache data locally for use on subsequent calls
     github_url : string
         Github repository where the data is stored
+    branch : string
+        The git branch to download from
     kws : dict, optional
         Passed to xarray.open_dataset
 
     """
     longdir = _os.path.expanduser(cache_dir)
     fullname = name + '.nc'
     localfile = _os.sep.join((longdir, fullname))
+    md5name = name + '.md5'
+    md5file = _os.sep.join((longdir, md5name))
 
     if not _os.path.exists(localfile):
 
@@ -52,8 +66,20 @@ def load_dataset(name, cache=True, cache_dir=_default_cache_dir,
         if not _os.path.isdir(longdir):
             _os.mkdir(longdir)
 
-        url = '/'.join((github_url, 'raw', 'master', fullname))
+        url = '/'.join((github_url, 'raw', branch, fullname))
         _urlretrieve(url, localfile)
+        url = '/'.join((github_url, 'raw', branch, md5name))
+        _urlretrieve(url, md5file)
+
+        localmd5 = file_md5_checksum(localfile)
+        with open(md5file, 'r') as f:
+            remotemd5 = f.read()
+        if localmd5 != remotemd5:
+            _os.remove(localfile)
+            msg = """
+            MD5 checksum does not match, try downloading dataset again.
+            """
+            raise IOError(msg)
 
     ds = _open_dataset(localfile, **kws).load()