Fix reporting certain config syntax errors

Change I0421c5a446d0b75194096b1d8f0e0866dae3b8f0 began including
BranchMatcher objects instead of strings in the SourceContext class
if an implied-branches pragma was supplied.  If a syntax error
occurs in a repo with such a pragma, the source context needs to
be serialized to zk, and that would fail.  To correct this, add
serialization methods to the source context and branch matchers.

Also correct an unrelated error where the syntax "- job:" would
fail to report the error to the user because the value None was
added to the list of config objects, and we always assume that
is a dict.  To correct this, raise the syntax error earlier in
that case.

Change-Id: Id7c1dff5e9865d21c3215bdc32c8fa2cb6603aaa

tests/unit/test_model.py

@@ -31,6 +31,7 @@ import zuul.lib.connections
 from tests.base import BaseTestCase, FIXTURE_DIR
 from zuul.lib.ansible import AnsibleManager
 from zuul.zk.zkobject import LocalZKContext
+from zuul import change_matcher
 
 
 class Dummy(object):
@@ -746,3 +747,22 @@ class TestRef(BaseTestCase):
 
         self.assertFalse(branch1.equals(change1))
         self.assertFalse(branch1.equals(tag1))
+
+
+class TestSourceContext(BaseTestCase):
+    def setUp(self):
+        super().setUp()
+        self.connection = Dummy(connection_name='dummy_connection')
+        self.source = Dummy(canonical_hostname='git.example.com',
+                            connection=self.connection)
+        self.project = model.Project('project', self.source)
+        self.context = model.SourceContext(
+            self.project.canonical_name, self.project.name,
+            self.project.connection_name, 'master', 'test', True)
+        self.context.implied_branches = [
+            change_matcher.BranchMatcher('foo'),
+            change_matcher.ImpliedBranchMatcher('foo'),
+        ]
+
+    def test_serialize(self):
+        self.context.deserialize(self.context.serialize())

tests/unit/test_v3.py

@@ -890,6 +890,39 @@ class TestBranchMismatch(ZuulTestCase):
             dict(name='project-test1', result='SUCCESS', changes='1,1'),
         ], ordered=False)
 
+    def test_implied_branch_matcher_pragma_syntax_error(self):
+        # Test that syntax errors are reported if the implied branch
+        # matcher pragma is set.  This catches potential errors when
+        # serializing configuration errors since the pragma causes
+        # extra information to be added to the error source context.
+        self.create_branch('org/project1', 'feature/test')
+        self.fake_gerrit.addEvent(
+            self.fake_gerrit.getFakeBranchCreatedEvent(
+                'org/project1', 'feature/test'))
+
+        in_repo_conf = textwrap.dedent(
+            """
+            - job:
+                name: project-test1
+                nodeset: bar
+            - pragma:
+                implied-branches:
+                  - master
+                  - feature/r1
+            """)
+        file_dict = {'zuul.yaml': in_repo_conf}
+        A = self.fake_gerrit.addFakeChange('org/project1', 'master', 'A',
+                                           files=file_dict)
+        self.fake_gerrit.addEvent(A.getPatchsetCreatedEvent(1))
+        self.waitUntilSettled()
+
+        self.assertHistory([])
+        self.assertEqual(A.data['status'], 'NEW')
+        self.assertEqual(A.reported, 1,
+                         "A should report failure")
+        self.assertIn('nodeset "bar" was not found', A.messages[0],
+                      "A should have a syntax error reported")
+
 
 class TestBranchRef(ZuulTestCase):
     tenant_config_file = 'config/branch-ref/main.yaml'
@@ -1717,6 +1750,25 @@ class TestInRepoConfig(ZuulTestCase):
         self.assertIn('while constructing a mapping', A.messages[0],
                       "A should have a syntax error reported")
 
+    def test_yaml_dict_error3(self):
+        in_repo_conf = textwrap.dedent(
+            """
+            - job:
+            """)
+
+        file_dict = {'.zuul.yaml': in_repo_conf}
+        A = self.fake_gerrit.addFakeChange('org/project', 'master', 'A',
+                                           files=file_dict)
+        A.addApproval('Code-Review', 2)
+        self.fake_gerrit.addEvent(A.addApproval('Approved', 1))
+        self.waitUntilSettled()
+
+        self.assertEqual(A.data['status'], 'NEW')
+        self.assertEqual(A.reported, 1,
+                         "A should report failure")
+        self.assertIn('is not a dictionary', A.messages[0],
+                      "A should have a syntax error reported")
+
     def test_yaml_duplicate_key_error(self):
         in_repo_conf = textwrap.dedent(
             """

zuul/change_matcher.py

@@ -82,6 +82,17 @@ class BranchMatcher(AbstractChangeMatcher):
                         return True
         return False
 
+    def serialize(self):
+        return {
+            "implied": self.exactmatch,
+            "regex": self._regex,
+        }
+
+    @classmethod
+    def deserialize(cls, data):
+        o = cls.__new__(cls, data['regex'])
+        return o
+
 
 class ImpliedBranchMatcher(BranchMatcher):
     exactmatch = True

zuul/model.py

@@ -1695,6 +1695,9 @@ class SourceContext(ConfigObject):
                 self.trusted == other.trusted)
 
     def serialize(self):
+        ibs = None
+        if self.implied_branches:
+            ibs = [ibm.serialize() for ibm in self.implied_branches]
         return {
             "project_canonical_name": self.project_canonical_name,
             "project_name": self.project_name,
@@ -1703,12 +1706,22 @@ class SourceContext(ConfigObject):
             "path": self.path,
             "trusted": self.trusted,
             "implied_branch_matchers": self.implied_branch_matchers,
-            "implied_branches": self.implied_branches,
+            "implied_branches": ibs,
         }
 
     @classmethod
     def deserialize(cls, data):
         o = cls.__new__(cls)
+        ibs = data.get('implied_branches')
+        if ibs:
+            data['implied_branches'] = []
+            for matcher_data in ibs:
+                if matcher_data['implied']:
+                    cls = change_matcher.ImpliedBranchMatcher
+                else:
+                    cls = change_matcher.BranchMatcher
+                data['implied_branches'].append(
+                    cls.deserialize(matcher_data))
         o.__dict__.update(data)
         return o
 
@@ -6738,6 +6751,8 @@ class UnparsedConfig(object):
             if len(item.keys()) > 1:
                 raise ConfigItemMultipleKeysError(item)
             key, value = list(item.items())[0]
+            if not isinstance(value, dict):
+                raise ConfigItemNotDictError(item)
             if key == 'project':
                 self.projects.append(value)
             elif key == 'job':