Add support for a skip-if filter on jobs

There was previously no way to skip a job if the contents of a given
patchset did not require it to be run.  This meant that tempest jobs
would run in response to patchsets that would not affect their
execution, like those that only modified documentation or unit tests.
This change introduces a 'skip-if' configuration option that allows
jobs to be configured to not run when specified criteria are met.

Change-Id: I9b261f03ec00426160d9396f3a20312e89b624d4
diff --git a/tests/test_model.py b/tests/test_model.py
new file mode 100644
index 0000000..a97f0a0
--- /dev/null
+++ b/tests/test_model.py
@@ -0,0 +1,45 @@
+# Copyright 2015 Red Hat, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+from zuul import change_matcher as cm
+from zuul import model
+
+from tests.base import BaseTestCase
+
+
+class TestJob(BaseTestCase):
+
+    @property
+    def job(self):
+        job = model.Job('job')
+        job.skip_if_matcher = cm.MatchAll([
+            cm.ProjectMatcher('^project$'),
+            cm.MatchAllFiles([cm.FileMatcher('^docs/.*$')]),
+        ])
+        return job
+
+    def test_change_matches_returns_false_for_matched_skip_if(self):
+        change = model.Change('project')
+        change.files = ['docs/foo']
+        self.assertFalse(self.job.changeMatches(change))
+
+    def test_change_matches_returns_true_for_unmatched_skip_if(self):
+        change = model.Change('project')
+        change.files = ['foo']
+        self.assertTrue(self.job.changeMatches(change))
+
+    def test_copy_retains_skip_if(self):
+        job = model.Job('job')
+        job.copy(self.job)
+        self.assertTrue(job.skip_if_matcher)