Conditionally adding silk urls leads to NoReverseMatch exception when running tests

I have the following in my root urls.py:

if settings.DEBUG:
    import debug_toolbar
    urlpatterns = [
        path('__debug__/', include(debug_toolbar.urls)),
        path('silk/', include('silk.urls', namespace='silk'))
    ] + urlpatterns

This works fine under runserver, however when running tests I get:

Traceback (most recent call last):
  File "/home/liav/.virtualenvs/grizzly.backend-POxoeTdG/lib/python3.7/site-packages/django/urls/base.py", line 75, in reverse
    extra, resolver = resolver.namespace_dict[ns]
KeyError: 'silk'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/liav/.virtualenvs/grizzly.backend-POxoeTdG/lib/python3.7/site-packages/silk/middleware.py", line 23, in silky_reverse
    r = reverse('silk:%s' % name, *args, **kwargs)
  File "/home/liav/.virtualenvs/grizzly.backend-POxoeTdG/lib/python3.7/site-packages/django/urls/base.py", line 86, in reverse
    raise NoReverseMatch("%s is not a registered namespace" % key)
django.urls.exceptions.NoReverseMatch: 'silk' is not a registered namespace

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/liav/dev/grizzly.backend/manage.py", line 15, in <module>
    execute_from_command_line(sys.argv)
  File "/home/liav/.virtualenvs/grizzly.backend-POxoeTdG/lib/python3.7/site-packages/django/core/management/__init__.py", line 381, in execute_from_command_line
    utility.execute()
  File "/home/liav/.virtualenvs/grizzly.backend-POxoeTdG/lib/python3.7/site-packages/django/core/management/__init__.py", line 375, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/home/liav/.virtualenvs/grizzly.backend-POxoeTdG/lib/python3.7/site-packages/django/core/management/commands/test.py", line 26, in run_from_argv
    super().run_from_argv(argv)
  File "/home/liav/.virtualenvs/grizzly.backend-POxoeTdG/lib/python3.7/site-packages/django/core/management/base.py", line 316, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/home/liav/.virtualenvs/grizzly.backend-POxoeTdG/lib/python3.7/site-packages/django/core/management/base.py", line 353, in execute
    output = self.handle(*args, **options)
  File "/home/liav/.virtualenvs/grizzly.backend-POxoeTdG/lib/python3.7/site-packages/django/core/management/commands/test.py", line 56, in handle
    failures = test_runner.run_tests(test_labels)
  File "/home/liav/.virtualenvs/grizzly.backend-POxoeTdG/lib/python3.7/site-packages/django/test/runner.py", line 605, in run_tests
    self.run_checks()
  File "/home/liav/.virtualenvs/grizzly.backend-POxoeTdG/lib/python3.7/site-packages/django/test/runner.py", line 567, in run_checks
    call_command('check', verbosity=self.verbosity)
  File "/home/liav/.virtualenvs/grizzly.backend-POxoeTdG/lib/python3.7/site-packages/django/core/management/__init__.py", line 148, in call_command
    return command.execute(*args, **defaults)
  File "/home/liav/.virtualenvs/grizzly.backend-POxoeTdG/lib/python3.7/site-packages/django/core/management/base.py", line 353, in execute
    output = self.handle(*args, **options)
  File "/home/liav/.virtualenvs/grizzly.backend-POxoeTdG/lib/python3.7/site-packages/django/core/management/commands/check.py", line 65, in handle
    fail_level=getattr(checks, options['fail_level']),
  File "/home/liav/.virtualenvs/grizzly.backend-POxoeTdG/lib/python3.7/site-packages/django/core/management/base.py", line 379, in check
    include_deployment_checks=include_deployment_checks,
  File "/home/liav/.virtualenvs/grizzly.backend-POxoeTdG/lib/python3.7/site-packages/django/core/management/base.py", line 366, in _run_checks
    return checks.run_checks(**kwargs)
  File "/home/liav/.virtualenvs/grizzly.backend-POxoeTdG/lib/python3.7/site-packages/django/core/checks/registry.py", line 71, in run_checks
    new_errors = check(app_configs=app_configs)
  File "/home/liav/.virtualenvs/grizzly.backend-POxoeTdG/lib/python3.7/site-packages/debug_toolbar/apps.py", line 34, in check_middleware
    if is_middleware_class(GZipMiddleware, middleware):
  File "/home/liav/.virtualenvs/grizzly.backend-POxoeTdG/lib/python3.7/site-packages/debug_toolbar/apps.py", line 75, in is_middleware_class
    middleware_cls = import_string(middleware_path)
  File "/home/liav/.virtualenvs/grizzly.backend-POxoeTdG/lib/python3.7/site-packages/django/utils/module_loading.py", line 17, in import_string
    module = import_module(module_path)
  File "/home/liav/.virtualenvs/grizzly.backend-POxoeTdG/lib/python3.7/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1006, in _gcd_import
  File "<frozen importlib._bootstrap>", line 983, in _find_and_load
  File "<frozen importlib._bootstrap>", line 967, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 677, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 726, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/home/liav/.virtualenvs/grizzly.backend-POxoeTdG/lib/python3.7/site-packages/silk/middleware.py", line 32, in <module>
    fpath = silky_reverse('summary')
  File "/home/liav/.virtualenvs/grizzly.backend-POxoeTdG/lib/python3.7/site-packages/silk/middleware.py", line 28, in silky_reverse
    r = reverse(name, *args, **kwargs)
  File "/home/liav/.virtualenvs/grizzly.backend-POxoeTdG/lib/python3.7/site-packages/django/urls/base.py", line 90, in reverse
    return iri_to_uri(resolver._reverse_with_prefix(view, prefix, *args, **kwargs))
  File "/home/liav/.virtualenvs/grizzly.backend-POxoeTdG/lib/python3.7/site-packages/django/urls/resolvers.py", line 622, in _reverse_with_prefix
    raise NoReverseMatch(msg)
django.urls.exceptions.NoReverseMatch: Reverse for 'summary' not found. 'summary' is not a valid view function or pattern name.

[m-ajay]

if DEBUG:
    INSTALLED_APPS.append('silk')

In settings.py

and

if 'silk' in settings.INSTALLED_APPS:
    urlpatterns = [
        path('silk/', include('silk.urls', namespace='silk')),
    ] + urlpatterns

in urls.py solved this issue for me.

[SebCorbin]

The original issue was about silk’s urls not being properly added, please ensure they are and open another issue with complete info about your code if needed.