Add a jobs_count method

The jobs_count method will return the total number of jobs on the
jenkins server.

Change-Id: I21e873646ed943d4fb4fdd61bd3b7d420fa1da55

jenkins/__init__.py

@@ -544,6 +544,13 @@ class Jenkins(object):
         if self.get_job_name(name) == name:
             return True
 
+    def jobs_count(self):
+        '''Get the number of jobs on the Jenkins server
+
+        :returns: Total number of jobs, ``int``
+        '''
+        return len(self.get_jobs())
+
     def assert_job_exists(self, name,
                           exception_message='job[%s] does not exist'):
         '''Raise an exception if a job does not exist

tests/test_jenkins.py

@@ -650,6 +650,18 @@ class JenkinsTest(unittest.TestCase):
             'Error communicating with server[http://example.com/]:'
             ' empty response')
 
+    @patch.object(jenkins.Jenkins, 'jenkins_open')
+    def test_jobs_count(self, jenkins_mock):
+        jobs = [
+            {u'url': u'http://localhost:8080/job/guava/', u'color': u'notbuilt', u'name': u'guava'},
+            {u'url': u'http://localhost:8080/job/kiwi/', u'color': u'blue', u'name': u'kiwi'},
+            {u'url': u'http://localhost:8080/job/lemon/', u'color': u'red', u'name': u'lemon'}
+        ]
+        job_info_to_return = {u'jobs': jobs}
+        jenkins_mock.return_value = json.dumps(job_info_to_return)
+        j = jenkins.Jenkins('http://example.com/', 'test', 'test')
+        self.assertEqual(j.jobs_count(), 3)
+
     @patch.object(jenkins.Jenkins, 'jenkins_open')
     def test_get_jobs(self, jenkins_mock):
         jobs = {