Clear out the dependency registry between tests

As part of the process during several tests setUp
where the backends are reloaded, automatic dependency
injection takes place. The REGISTRY is being updated
with new providers and it's also looking up the
required dependencies. Some of the providers for the
requirements may not have been updated yet with the
new provider object, so it loads an object that
was created from a previous test run rather than the
current one. This can cause tests to
fail when one class gets a ref to the old one
(it depends on the order that the tests are run).

This change clears out the registry of providers before
loading backends. It only affects testing.

Part of fix for bug 1204605

Change-Id: Ib845493fa13531225e4be7e3b6cc315b9d19a0f4

1 files changed, 17 insertions, 0 deletions

diff --git a/tests/test_injection.py b/tests/test_injection.py
index 4b6fc8ba..08ccd7c7 100644
--- a/tests/test_injection.py
+++ b/tests/test_injection.py
@@ -165,3 +165,20 @@ class TestDependencyInjection(unittest.TestCase):
 
         with self.assertRaises(dependency.UnresolvableDependencyException):
             Consumer()
+
+    def test_reset(self):
+        # Can reset the registry of providers.
+
+        p_id = uuid.uuid4().hex
+
+        @dependency.provider(p_id)
+        class P(object):
+            pass
+
+        p_inst = P()
+
+        self.assertIs(dependency.REGISTRY[p_id], p_inst)
+
+        dependency.reset()
+
+        self.assertFalse(dependency.REGISTRY)