TST: Add a fixture enabling SRTM login using envvars.

lib/cartopy/io/srtm.py

@@ -413,11 +413,12 @@ def __init__(self,
         Downloader.__init__(self, None,
                             target_path_template,
                             pre_downloaded_path_template)
-        warnings.warn('SRTM requires an account set up and log in to access.'
-                      'use of this class is likely to fail with'
-                      ' HTTP 401 errors.')
 
     def url(self, format_dict):
+        warnings.warn('SRTM requires an account set up and log in to access. '
+                      'Use of this Downloader is likely to fail with HTTP 401 '
+                      'errors.')
+
         # override the url method, looking up the url from the
         # ``SRTMDownloader._SRTM_LOOKUP_MASK`` array
         lat = int(format_dict['y'][1:])

lib/cartopy/tests/io/test_srtm.py

@@ -29,8 +29,40 @@
 from .test_downloaders import download_to_temp  # noqa: F401 (used as fixture)
 
 
-pytestmark = [pytest.mark.skip('SRTM login not supported'),
-              pytest.mark.network]
+pytestmark = [pytest.mark.network,
+              pytest.mark.filterwarnings('ignore:SRTM requires an account'),
+              pytest.mark.usefixtures('srtm_login_or_skip')]
+
+
+@pytest.fixture
+def srtm_login_or_skip(monkeypatch):
+    import os
+    try:
+        srtm_username = os.environ['SRTM_USERNAME']
+    except KeyError:
+        pytest.skip('SRTM_USERNAME environment variable is unset.')
+    try:
+        srtm_password = os.environ['SRTM_PASSWORD']
+    except KeyError:
+        pytest.skip('SRTM_PASSWORD environment variable is unset.')
+
+    from six.moves.urllib.request import (HTTPBasicAuthHandler,
+                                          HTTPCookieProcessor,
+                                          HTTPPasswordMgrWithDefaultRealm,
+                                          build_opener)
+    from six.moves.http_cookiejar import CookieJar
+
+    password_manager = HTTPPasswordMgrWithDefaultRealm()
+    password_manager.add_password(
+        None,
+        "https://urs.earthdata.nasa.gov",
+        srtm_username,
+        srtm_password)
+    cookie_jar = CookieJar()
+    opener = build_opener(HTTPBasicAuthHandler(password_manager),
+                          HTTPCookieProcessor(cookie_jar))
+
+    monkeypatch.setattr(cartopy.io, 'urlopen', opener.open)
 
 
 class TestRetrieve(object):