Tidy error checking+reporting; remove @skip_data; remove unused impor…

…ts.Â

lib/iris/tests/test_image_json.py

@@ -29,42 +29,44 @@
 import json
 import os
 import requests
-import unittest
-import time
 
 
 @tests.skip_inet
-@tests.skip_data
 class TestImageFile(tests.IrisTest):
     def test_resolve(self):
         # https://developer.github.com/v3/#user-agent-required
         headers = {'User-Agent': 'scitools-bot'}
         rate_limit_uri = 'https://api.github.com/rate_limit'
         rl = requests.get(rate_limit_uri, headers=headers)
-        some_left = False
-        if rl.status_code == 200:
-            rates = rl.json()
-            remaining = rates.get('rate', {})
-            ghapi_remaining = remaining.get('remaining')
-        else:
-            ghapi_remaining = 0
+        if rl.status_code != 200:
+            msg = 'Get request on {} failed : rc={}.'
+            raise ValueError(msg.format(rate_limit_uri, rl.status_code))
 
-        # Only run this test if there are IP based rate limited calls left.
+        # Abort test if there are < 3 IP based rate limited calls left.
         # 3 is an engineering tolerance, in case of race conditions.
-        amin = 3
-        if ghapi_remaining < amin:
+        rl_json = rl.json()
+        rate_info = rl_json.get('rate', {})
+        reqs_left, reset_level, next_time_epoch_secs = (
+            rate_info.get(key)
+            for key in ('remaining', 'limit', 'reset'))
+        if any(not isinstance(value, int)
+               for value in (reqs_left, reset_level, next_time_epoch_secs)):
+            msg = 'Failed to parse result of GET {} : result={}'.format(
+               rate_limit_uri, rl_json)
+            raise ValueError(msg)
+
+        min_requests = 3
+        if reqs_left < min_requests:
             msg = ('This test failed because it hit a GitHub web API request '
                    'rate-limit, \n'
                    'for anonymous requests by "User-Agent: scitools-bot".\n'
                    'N-calls-left is {}, less than margin allowance of {}.\n'
                    'Next reset due : {} requests at {}\n.'
                    'Please retry after that time.')
-            reset_level = rates['rate']['limit']
-            next_time_epoch_secs = rates['rate']['reset']
             from cf_units import Unit
             reset_date = Unit('seconds since epoch').num2date(
                 next_time_epoch_secs)
-            raise ValueError(msg.format(ghapi_remaining, amin,
+            raise ValueError(msg.format(reqs_left, min_requests,
                                         reset_level, reset_date))
 
         iuri = ('https://api.github.com/repos/scitools/'