From 89e25403ae9dfcdc3eabd66469226d3036c6cc06 Mon Sep 17 00:00:00 2001
From: Chris Beaven <smileychris@gmail.com>
Date: Sun, 17 Apr 2011 04:52:17 +0000
Subject: [PATCH] Fixes #15814 -- Added a test util to abstract the process of
 using a test template loader

git-svn-id: http://code.djangoproject.com/svn/django/trunk@16030 bcc190cf-cafb-0310-a4f2-bffc1f526a37
---
 django/test/utils.py                     | 43 +++++++++++++++++++++++-
 tests/regressiontests/templates/tests.py | 22 ++++--------
 2 files changed, 49 insertions(+), 16 deletions(-)

diff --git a/django/test/utils.py b/django/test/utils.py
index 2672594916..bf1dc4f165 100644
--- a/django/test/utils.py
+++ b/django/test/utils.py
@@ -6,12 +6,15 @@ from django.conf import settings
 from django.core import mail
 from django.core.mail.backends import locmem
 from django.test import signals
-from django.template import Template
+from django.template import Template, loader, TemplateDoesNotExist
+from django.template.loaders import cached
 from django.utils.translation import deactivate
 
 __all__ = ('Approximate', 'ContextList', 'setup_test_environment',
        'teardown_test_environment', 'get_runner')
 
+RESTORE_LOADERS_ATTR = '_original_template_source_loaders'
+
 
 class Approximate(object):
     def __init__(self, val, places=7):
@@ -119,3 +122,41 @@ def get_runner(settings):
     test_module = __import__(test_module_name, {}, {}, test_path[-1])
     test_runner = getattr(test_module, test_path[-1])
     return test_runner
+
+
+def setup_test_template_loader(templates_dict, use_cached_loader=False):
+    """
+    Changes Django to only find templates from within a dictionary (where each
+    key is the template name and each value is the corresponding template
+    content to return).
+
+    Use meth:`restore_template_loaders` to restore the original loaders.
+    """
+    if hasattr(loader, RESTORE_LOADERS_ATTR):
+        raise Exception("loader.%s already exists" % RESTORE_LOADERS_ATTR)
+
+    def test_template_loader(template_name, template_dirs=None):
+        "A custom template loader that loads templates from a dictionary."
+        try:
+            return (templates_dict[template_name], "test:%s" % template_name)
+        except KeyError:
+            raise TemplateDoesNotExist(template_name)
+
+    if use_cached_loader:
+        template_loader = cached.Loader(('test_template_loader',))
+        template_loader._cached_loaders = (test_template_loader,)
+    else:
+        template_loader = test_template_loader
+
+    setattr(loader, RESTORE_LOADERS_ATTR, loader.template_source_loaders)
+    loader.template_source_loaders = (template_loader,)
+    return template_loader
+
+
+def restore_template_loaders():
+    """
+    Restores the original template loaders after
+    :meth:`setup_test_template_loader` has been run.
+    """
+    loader.template_source_loaders = getattr(loader, RESTORE_LOADERS_ATTR)
+    delattr(loader, RESTORE_LOADERS_ATTR)
diff --git a/tests/regressiontests/templates/tests.py b/tests/regressiontests/templates/tests.py
index e8881fc83b..a051d7335e 100644
--- a/tests/regressiontests/templates/tests.py
+++ b/tests/regressiontests/templates/tests.py
@@ -18,7 +18,8 @@ from django.template import base as template_base
 from django.core import urlresolvers
 from django.template import loader
 from django.template.loaders import app_directories, filesystem, cached
-from django.test.utils import get_warnings_state, restore_warnings_state
+from django.test.utils import get_warnings_state, restore_warnings_state,\
+    setup_test_template_loader, restore_template_loaders
 from django.utils import unittest
 from django.utils.translation import activate, deactivate, ugettext as _
 from django.utils.safestring import mark_safe
@@ -390,19 +391,10 @@ class Templates(unittest.TestCase):
 
         template_tests.update(filter_tests)
 
-        # Register our custom template loader.
-        def test_template_loader(template_name, template_dirs=None):
-            "A custom template loader that loads the unit-test templates."
-            try:
-                return (template_tests[template_name][0] , "test:%s" % template_name)
-            except KeyError:
-                raise template.TemplateDoesNotExist(template_name)
-
-        cache_loader = cached.Loader(('test_template_loader',))
-        cache_loader._cached_loaders = (test_template_loader,)
-
-        old_template_loaders = loader.template_source_loaders
-        loader.template_source_loaders = [cache_loader]
+        cache_loader = setup_test_template_loader(
+            dict([(name, t[0]) for name, t in template_tests.iteritems()]),
+            use_cached_loader=True,
+        )
 
         failures = []
         tests = template_tests.items()
@@ -490,7 +482,7 @@ class Templates(unittest.TestCase):
                 expected_invalid_str = 'INVALID'
                 template_base.invalid_var_format_string = False
 
-        loader.template_source_loaders = old_template_loaders
+        restore_template_loaders()
         deactivate()
         settings.TEMPLATE_DEBUG = old_td
         settings.TEMPLATE_STRING_IF_INVALID = old_invalid