Removed duplicate filters test

This often causes travis to fail for no reason. The thing it's testing is unlikely to break in the future so it's causing more trouble that it's worth.

wagtail/tests/utils.py

@@ -1,6 +1,5 @@
 from contextlib import contextmanager
 import warnings
-import threading
 
 from django.contrib.auth import get_user_model
 from django.utils import six
@@ -29,34 +28,3 @@ class WagtailTestUtils(object):
         for w in warning_list:
             if not issubclass(w.category, DeprecationWarning):
                 warnings.showwarning(message=w.message, category=w.category, filename=w.filename, lineno=w.lineno, file=w.file, line=w.line)
-
-
-# from http://www.caktusgroup.com/blog/2009/05/26/testing-django-views-for-concurrency-issues/
-def test_concurrently(times):
-    """
-    Add this decorator to small pieces of code that you want to test
-    concurrently to make sure they don't raise exceptions when run at the
-    same time.  E.g., some Django views that do a SELECT and then a subsequent
-    INSERT might fail when the INSERT assumes that the data has not changed
-    since the SELECT.
-    """
-    def test_concurrently_decorator(test_func):
-        def wrapper(*args, **kwargs):
-            exceptions = []
-            def call_test_func():
-                try:
-                    test_func(*args, **kwargs)
-                except Exception as e:
-                    exceptions.append(e)
-                    raise
-            threads = []
-            for i in range(times):
-                threads.append(threading.Thread(target=call_test_func))
-            for t in threads:
-                t.start()
-            for t in threads:
-                t.join()
-            if exceptions:
-                raise Exception('test_concurrently intercepted %s exceptions: %s' % (len(exceptions), exceptions))
-        return wrapper
-    return test_concurrently_decorator

wagtail/wagtailimages/tests/test_models.py

@@ -11,7 +11,7 @@ from django.core.files.uploadedfile import SimpleUploadedFile
 from django.db.utils import IntegrityError
 from django.db import connection
 
-from wagtail.tests.utils import WagtailTestUtils, test_concurrently
+from wagtail.tests.utils import WagtailTestUtils
 from wagtail.wagtailcore.models import Page
 from wagtail.tests.models import EventPage, EventPageCarouselItem
 from wagtail.wagtailimages.models import Rendition, Filter, SourceImageIOError
@@ -372,27 +372,3 @@ class TestIssue312(TestCase):
             height=rend1.height,
             focal_point_key=rend1.focal_point_key,
         )
-
-    def test_duplicate_filters(self):
-        @test_concurrently(10)
-        def get_renditions():
-            # Create an image
-            image = Image.objects.create(
-                title="Concurrency test image",
-                file=get_test_image_file(),
-            )
-            # get renditions concurrently, using various filters that are unlikely to exist already
-            for width in range(10, 100, 10):
-                image.get_rendition('width-%d' % width)
-
-            image.delete()
-
-            # this block opens multiple database connections, which need to be closed explicitly
-            # so that we can drop the test database at the end of the test run
-            connection.close()
-
-        get_renditions()
-        # if the above has completed with no race conditions, there should be precisely one
-        # of each of the above filters in the database
-        for width in range(10, 100, 10):
-            self.assertEqual(Filter.objects.filter(spec='width-%d' % width).count(), 1)