Merge "Handle zuul.yaml files with only comments"

tests/fixtures/config/empty-config-file/git/common-config/README

@@ -0,0 +1 @@
+test

tests/fixtures/config/empty-config-file/git/common-config/playbooks/run.yaml

@@ -0,0 +1,2 @@
+- hosts: all
+  tasks: []

tests/fixtures/config/empty-config-file/git/common-config/zuul.yaml

@@ -0,0 +1 @@
+# test comment

tests/fixtures/config/empty-config-file/git/org_project/README

@@ -0,0 +1 @@
+test

tests/fixtures/config/empty-config-file/main.yaml

@@ -0,0 +1,8 @@
+- tenant:
+    name: tenant-one
+    source:
+      gerrit:
+        config-projects:
+          - common-config
+        untrusted-projects:
+          - org/project

tests/unit/test_v3.py

@@ -1318,6 +1318,18 @@ class TestCentralJobs(ZuulTestCase):
         self._test_central_template_on_branch('stable', 'master')
 
 
+class TestEmptyConfigFile(ZuulTestCase):
+    tenant_config_file = 'config/empty-config-file/main.yaml'
+
+    def test_empty_config_file(self):
+        # Tests that a config file with only comments does not cause
+        # an error.
+        tenant = self.scheds.first.sched.abide.tenants.get('tenant-one')
+        self.assertEquals(
+            len(tenant.layout.loading_errors), 0,
+            "No error should have been accumulated")
+
+
 class TestInRepoConfig(ZuulTestCase):
     # A temporary class to hold new tests while others are disabled
 

zuul/model.py

@@ -7694,6 +7694,10 @@ class UnparsedConfig(object):
         return r
 
     def extend(self, conf):
+        # conf might be None in the case of a file with only comments.
+        if conf is None:
+            return
+
         if isinstance(conf, UnparsedConfig):
             self.pragmas.extend(conf.pragmas)
             self.pipelines.extend(conf.pipelines)