Add branch cache fetch failure tests

These two tests exercise the LookupError code paths in the branch
cache a bit more.  In particular, we now have a test that verifies
that a failure in fetching will result in a retry later.

Change-Id: Ia83b0233ccc31f018a61093d02fd1ce68547f9c0

2 files changed, 61 insertions, 0 deletions

diff --git a/tests/unit/test_connection.py b/tests/unit/test_connection.py
index ab781252e..b4c155240 100644
--- a/tests/unit/test_connection.py
+++ b/tests/unit/test_connection.py
@@ -849,3 +849,52 @@ class TestElasticsearchConnection(AnsibleZuulTestCase):
 
         # Check if there is a secret leak
         self.assertFalse('test_secret' in build_doc['job_vars'])
+
+
+class TestConnectionsBranchCache(ZuulTestCase):
+    config_file = "zuul-gerrit-github.conf"
+    tenant_config_file = 'config/multi-driver/main.yaml'
+
+    def test_branch_cache_fetch_error(self):
+        # Test that a fetch error stores the right value in the branch cache
+        tenant = self.scheds.first.sched.abide.tenants.get('tenant-one')
+        connection = self.scheds.first.connections.connections['github']
+        source = connection.source
+        project = source.getProject('org/project1')
+
+        # Patch the fetch method so that it fails
+        orig = connection._fetchProjectBranches
+
+        def fail(*args, **kw):
+            raise Exception("Unable to fetch branches")
+        self.patch(connection, '_fetchProjectBranches', fail)
+
+        # Clear the branch cache so we start with nothing
+        connection.clearBranchCache()
+
+        # Verify that we raise an error when we try to get branches
+        # for a missing project
+        self.assertRaises(
+            Exception,
+            lambda: connection.getProjectBranches(project, tenant))
+        # This should happen again (ie, we should retry since we don't
+        # have an entry)
+        self.assertRaises(
+            Exception,
+            lambda: connection.getProjectBranches(project, tenant))
+
+        # Restore the normal fetch method and verify that the cache
+        # works as expected
+        self.patch(connection, '_fetchProjectBranches', orig)
+        branches = connection.getProjectBranches(project, tenant)
+        self.assertEqual(['master'], branches)
+
+        # Ensure that the empty list of branches is valid and is not
+        # seen as an error
+        newproject = source.getProject('org/newproject')
+        connection.addProject(newproject)
+        tpc = zuul.model.TenantProjectConfig(newproject)
+        tpc.exclude_unprotected_branches = True
+        tenant.addUntrustedProject(tpc)
+        branches = connection.getProjectBranches(newproject, tenant)
+        self.assertEqual([], branches)
diff --git a/tests/unit/test_zk.py b/tests/unit/test_zk.py
index e45629bef..eadf5c855 100644
--- a/tests/unit/test_zk.py
+++ b/tests/unit/test_zk.py
@@ -1947,6 +1947,18 @@ class TestBranchCache(ZooKeeperBaseTestCase):
             data1['project1']['all']
         )
 
+    def test_branch_cache_lookup_error(self):
+        # Test that a missing branch cache entry results in a LookupError
+        conn = DummyConnection()
+        cache = BranchCache(self.zk_client, conn, self.component_registry)
+        self.assertRaises(
+            LookupError,
+            lambda: cache.getProjectBranches('project1', True)
+        )
+        self.assertIsNone(
+            cache.getProjectBranches('project1', True, default=None)
+        )
+
 
 class TestConfigurationErrorList(ZooKeeperBaseTestCase):
     def test_config_error_list(self):