diff --git a/ckanext/harvest/logic/action/create.py b/ckanext/harvest/logic/action/create.py
index 203b9eb..d904c5c 100644
--- a/ckanext/harvest/logic/action/create.py
+++ b/ckanext/harvest/logic/action/create.py
@@ -148,15 +148,15 @@ def _check_for_existing_jobs(context, source_id):
     return exist
 
 def harvest_object_create(context, data_dict):
-    """ Create a new harvest object
+    ''' Create a new harvest object
 
     :type guid: string (optional)
     :type content: string (optional)
-    :type job_id: string 
+    :type job_id: string
     :type source_id: string (optional)
     :type package_id: string (optional)
     :type extras: dict (optional)
-    """
+    '''
     check_access('harvest_object_create', context, data_dict)
     data, errors = _validate(data_dict, harvest_object_create_schema(), context)
 
diff --git a/ckanext/harvest/logic/action/delete.py b/ckanext/harvest/logic/action/delete.py
index 405aa3a..70e8c0a 100644
--- a/ckanext/harvest/logic/action/delete.py
+++ b/ckanext/harvest/logic/action/delete.py
@@ -2,12 +2,11 @@ import logging
 
 from ckan import plugins as p
 
-
 log = logging.getLogger(__name__)
 
+
 def harvest_source_delete(context, data_dict):
-    '''
-    Deletes an existing harvest source
+    '''Deletes an existing harvest source
 
     This method just proxies the request to package_delete,
     which will delete the actual harvest type dataset and the
@@ -15,10 +14,6 @@ def harvest_source_delete(context, data_dict):
 
     :param id: the name or id of the harvest source to delete
     :type id: string
-
-    :returns: the newly created harvest source
-    :rtype: dictionary
-
     '''
     log.info('Deleting harvest source: %r', data_dict)
 
@@ -28,7 +23,8 @@ def harvest_source_delete(context, data_dict):
 
     if context.get('clear_source', False):
 
-        # We need the id, the name won't work
+        # We need the id. The name won't work.
         package_dict = p.toolkit.get_action('package_show')(context, data_dict)
 
-        p.toolkit.get_action('harvest_source_clear')(context, {'id': package_dict['id']})
+        p.toolkit.get_action('harvest_source_clear')(
+            context, {'id': package_dict['id']})
diff --git a/ckanext/harvest/logic/action/update.py b/ckanext/harvest/logic/action/update.py
index bca776c..bd06d2c 100644
--- a/ckanext/harvest/logic/action/update.py
+++ b/ckanext/harvest/logic/action/update.py
@@ -29,12 +29,13 @@ from ckanext.harvest.model import HarvestSource, HarvestJob, HarvestObject
 from ckanext.harvest.logic import HarvestJobExists, NoNewHarvestJobError
 from ckanext.harvest.logic.dictization import harvest_job_dictize
 
-from ckanext.harvest.logic.action.get import harvest_source_show, harvest_job_list, _get_sources_for_user
-
+from ckanext.harvest.logic.action.get import (
+    harvest_source_show, harvest_job_list, _get_sources_for_user)
 
 log = logging.getLogger(__name__)
 
-def harvest_source_update(context,data_dict):
+
+def harvest_source_update(context, data_dict):
     '''
     Updates an existing harvest source
 
@@ -69,10 +70,8 @@ def harvest_source_update(context,data_dict):
         type. Should be a serialized as JSON. (optional)
     :type config: string
 
-
     :returns: the newly created harvest source
     :rtype: dictionary
-
     '''
     log.info('Updating harvest source: %r', data_dict)
 
@@ -92,11 +91,11 @@ def harvest_source_clear(context, data_dict):
 
     :param id: the id of the harvest source to clear
     :type id: string
-
     '''
-    check_access('harvest_source_clear',context,data_dict)
 
-    harvest_source_id = data_dict.get('id', None)
+    check_access('harvest_source_clear', context, data_dict)
+
+    harvest_source_id = data_dict.get('id')
 
     source = HarvestSource.get(harvest_source_id)
     if not source:
@@ -110,68 +109,96 @@ def harvest_source_clear(context, data_dict):
 
     model = context['model']
 
-    sql = "select id from related where id in (select related_id from related_dataset where dataset_id in (select package_id from harvest_object where harvest_source_id = '{harvest_source_id}'));".format(harvest_source_id=harvest_source_id)
+    sql = '''select id from related where id in (
+              select related_id from related_dataset where dataset_id in (
+                  select package_id from harvest_object
+                  where harvest_source_id = '{harvest_source_id}'));'''.format(
+        harvest_source_id=harvest_source_id)
     result = model.Session.execute(sql)
     ids = []
     for row in result:
         ids.append(row[0])
     related_ids = "('" + "','".join(ids) + "')"
 
-    sql = '''begin; 
-    update package set state = 'to_delete' where id in (select package_id from harvest_object where harvest_source_id = '{harvest_source_id}');'''.format(
+    sql = '''begin;
+        update package set state = 'to_delete' where id in (
+            select package_id from harvest_object
+            where harvest_source_id = '{harvest_source_id}');'''.format(
         harvest_source_id=harvest_source_id)
 
     # CKAN-2.3 or above: delete resource views, resource revisions & resources
     if toolkit.check_ckan_version(min_version='2.3'):
         sql += '''
-        delete from resource_view where resource_id in (select id from resource where package_id in (select id from package where state = 'to_delete' ));
-        delete from resource_revision where package_id in (select id from package where state = 'to_delete' );
-        delete from resource where package_id in (select id from package where state = 'to_delete' );
+        delete from resource_view where resource_id in (
+            select id from resource where package_id in (
+                select id from package where state = 'to_delete'));
+        delete from resource_revision where package_id in (
+            select id from package where state = 'to_delete');
+        delete from resource where package_id in (
+            select id from package where state = 'to_delete');
         '''
     # Backwards-compatibility: support ResourceGroup (pre-CKAN-2.3)
     else:
         sql += '''
-        delete from resource_revision where resource_group_id in 
-        (select id from resource_group where package_id in 
-        (select id from package where state = 'to_delete'));
-        delete from resource where resource_group_id in 
-        (select id from resource_group where package_id in 
-        (select id from package where state = 'to_delete'));
-        delete from resource_group_revision where package_id in 
-        (select id from package where state = 'to_delete');
-        delete from resource_group where package_id  in 
-        (select id from package where state = 'to_delete');
+        delete from resource_revision where resource_group_id in (
+            select id from resource_group where package_id in (
+                select id from package where state = 'to_delete'));
+        delete from resource where resource_group_id in (
+            select id from resource_group where package_id in (
+                select id from package where state = 'to_delete'));
+        delete from resource_group_revision where package_id in (
+            select id from package where state = 'to_delete');
+        delete from resource_group where package_id in (
+            select id from package where state = 'to_delete');
         '''
     # CKAN pre-2.5: authz models were removed in migration 078
     if toolkit.check_ckan_version(max_version='2.4.99'):
         sql += '''
-        delete from package_role where package_id in
-        (select id from package where state = 'to_delete');
-        delete from user_object_role where id not in
-        (select user_object_role_id from package_role) and context = 'Package';
+        delete from package_role where package_id in (
+            select id from package where state = 'to_delete');
+        delete from user_object_role where id not in (
+            select user_object_role_id from package_role)
+            and context = 'Package';
         '''
 
-
     sql += '''
-    delete from harvest_object_error where harvest_object_id in (select id from harvest_object where harvest_source_id = '{harvest_source_id}');
-    delete from harvest_object_extra where harvest_object_id in (select id from harvest_object where harvest_source_id = '{harvest_source_id}');
+    delete from harvest_object_error where harvest_object_id in (
+        select id from harvest_object
+        where harvest_source_id = '{harvest_source_id}');
+    delete from harvest_object_extra where harvest_object_id in (
+        select id from harvest_object
+        where harvest_source_id = '{harvest_source_id}');
     delete from harvest_object where harvest_source_id = '{harvest_source_id}';
-    delete from harvest_gather_error where harvest_job_id in (select id from harvest_job where source_id = '{harvest_source_id}');
+    delete from harvest_gather_error where harvest_job_id in (
+        select id from harvest_job where source_id = '{harvest_source_id}');
     delete from harvest_job where source_id = '{harvest_source_id}';
-    delete from package_tag_revision where package_id in (select id from package where state = 'to_delete');
-    delete from member_revision where table_id in (select id from package where state = 'to_delete');
-    delete from package_extra_revision where package_id in (select id from package where state = 'to_delete');
-    delete from package_revision where id in (select id from package where state = 'to_delete');
-    delete from package_tag where package_id in (select id from package where state = 'to_delete');
-    delete from package_extra where package_id in (select id from package where state = 'to_delete');
-    delete from package_relationship_revision where subject_package_id in (select id from package where state = 'to_delete');
-    delete from package_relationship_revision where object_package_id in (select id from package where state = 'to_delete');
-    delete from package_relationship where subject_package_id in (select id from package where state = 'to_delete');
-    delete from package_relationship where object_package_id in (select id from package where state = 'to_delete');
-    delete from member where table_id in (select id from package where state = 'to_delete');
-    delete from related_dataset where dataset_id in (select id from package where state = 'to_delete');
+    delete from package_tag_revision where package_id in (
+        select id from package where state = 'to_delete');
+    delete from member_revision where table_id in (
+        select id from package where state = 'to_delete');
+    delete from package_extra_revision where package_id in (
+        select id from package where state = 'to_delete');
+    delete from package_revision where id in (
+        select id from package where state = 'to_delete');
+    delete from package_tag where package_id in (
+        select id from package where state = 'to_delete');
+    delete from package_extra where package_id in (
+        select id from package where state = 'to_delete');
+    delete from package_relationship_revision where subject_package_id in (
+        select id from package where state = 'to_delete');
+    delete from package_relationship_revision where object_package_id in (
+        select id from package where state = 'to_delete');
+    delete from package_relationship where subject_package_id in (
+        select id from package where state = 'to_delete');
+    delete from package_relationship where object_package_id in (
+        select id from package where state = 'to_delete');
+    delete from member where table_id in (
+        select id from package where state = 'to_delete');
+    delete from related_dataset where dataset_id in (
+        select id from package where state = 'to_delete');
     delete from related where id in {related_ids};
-    delete from package where id in (select id from package where state = 'to_delete');
+    delete from package where id in (
+        select id from package where state = 'to_delete');
     commit;
     '''.format(
         harvest_source_id=harvest_source_id, related_ids=related_ids)
@@ -183,7 +210,8 @@ def harvest_source_clear(context, data_dict):
 
     return {'id': harvest_source_id}
 
-def harvest_source_index_clear(context,data_dict):
+
+def harvest_source_index_clear(context, data_dict):
     '''
     Clears all datasets, jobs and objects related to a harvest source, but
     keeps the source itself.  This is useful to clean history of long running
@@ -193,8 +221,8 @@ def harvest_source_index_clear(context,data_dict):
     :type id: string
     '''
 
-    check_access('harvest_source_clear',context,data_dict)
-    harvest_source_id = data_dict.get('id',None)
+    check_access('harvest_source_clear', context, data_dict)
+    harvest_source_id = data_dict.get('id')
 
     source = HarvestSource.get(harvest_source_id)
     if not source:
@@ -204,8 +232,8 @@ def harvest_source_index_clear(context,data_dict):
     harvest_source_id = source.id
 
     conn = make_connection()
-    query = ''' +%s:"%s" +site_id:"%s" ''' % ('harvest_source_id', harvest_source_id,
-                                            config.get('ckan.site_id'))
+    query = ''' +%s:"%s" +site_id:"%s" ''' % (
+        'harvest_source_id', harvest_source_id, config.get('ckan.site_id'))
     try:
         conn.delete_query(query)
         if asbool(config.get('ckan.search.solr_commit', 'true')):
@@ -240,17 +268,17 @@ def harvest_objects_import(context, data_dict):
     :type package_id: string
     '''
     log.info('Harvest objects import: %r', data_dict)
-    check_access('harvest_objects_import',context,data_dict)
+    check_access('harvest_objects_import', context, data_dict)
 
     model = context['model']
     session = context['session']
-    source_id = data_dict.get('source_id',None)
-    harvest_object_id = data_dict.get('harvest_object_id',None)
-    package_id_or_name = data_dict.get('package_id',None)
+    source_id = data_dict.get('source_id')
+    harvest_object_id = data_dict.get('harvest_object_id')
+    package_id_or_name = data_dict.get('package_id')
 
-    segments = context.get('segments',None)
+    segments = context.get('segments')
 
-    join_datasets = context.get('join_datasets',True)
+    join_datasets = context.get('join_datasets', True)
 
     if source_id:
         source = HarvestSource.get(source_id)
@@ -262,43 +290,48 @@ def harvest_objects_import(context, data_dict):
             log.warn('Harvest source %s is not active.', source_id)
             raise Exception('This harvest source is not active')
 
-        last_objects_ids = session.query(HarvestObject.id) \
-                .join(HarvestSource) \
-                .filter(HarvestObject.source==source) \
-                .filter(HarvestObject.current==True)
+        last_objects_ids = \
+            session.query(HarvestObject.id) \
+                   .join(HarvestSource) \
+                   .filter(HarvestObject.source == source) \
+                   .filter(HarvestObject.current == True)
 
     elif harvest_object_id:
-        last_objects_ids = session.query(HarvestObject.id) \
-                .filter(HarvestObject.id==harvest_object_id)
+        last_objects_ids = \
+            session.query(HarvestObject.id) \
+                   .filter(HarvestObject.id == harvest_object_id)
     elif package_id_or_name:
-        last_objects_ids = session.query(HarvestObject.id) \
-            .join(Package) \
-            .filter(HarvestObject.current==True) \
-            .filter(Package.state==u'active') \
-            .filter(or_(Package.id==package_id_or_name,
-                        Package.name==package_id_or_name))
+        last_objects_ids = \
+            session.query(HarvestObject.id) \
+                   .join(Package) \
+                   .filter(HarvestObject.current == True) \
+                   .filter(Package.state == u'active') \
+                   .filter(or_(Package.id == package_id_or_name,
+                               Package.name == package_id_or_name))
         join_datasets = False
     else:
-        last_objects_ids = session.query(HarvestObject.id) \
-                .filter(HarvestObject.current==True)
+        last_objects_ids = \
+            session.query(HarvestObject.id) \
+                   .filter(HarvestObject.current == True)
 
     if join_datasets:
         last_objects_ids = last_objects_ids.join(Package) \
-            .filter(Package.state==u'active')
+            .filter(Package.state == u'active')
 
     last_objects_ids = last_objects_ids.all()
 
     last_objects_count = 0
 
     for obj_id in last_objects_ids:
-        if segments and str(hashlib.md5(obj_id[0]).hexdigest())[0] not in segments:
+        if segments and \
+                str(hashlib.md5(obj_id[0]).hexdigest())[0] not in segments:
             continue
 
         obj = session.query(HarvestObject).get(obj_id)
 
         for harvester in PluginImplementations(IHarvester):
             if harvester.info()['name'] == obj.source.type:
-                if hasattr(harvester,'force_import'):
+                if hasattr(harvester, 'force_import'):
                     harvester.force_import = True
                 harvester.import_stage(obj)
                 break
@@ -306,7 +339,8 @@ def harvest_objects_import(context, data_dict):
     log.info('Harvest objects imported: %s', last_objects_count)
     return last_objects_count
 
-def _caluclate_next_run(frequency):
+
+def _calculate_next_run(frequency):
 
     now = datetime.datetime.utcnow()
     if frequency == 'ALWAYS':
@@ -318,7 +352,7 @@ def _caluclate_next_run(frequency):
     if frequency == 'DAILY':
         return now + datetime.timedelta(days=1)
     if frequency == 'MONTHLY':
-        if now.month in (4,6,9,11):
+        if now.month in (4, 6, 9, 11):
             days = 30
         elif now.month == 2:
             if now.year % 4 == 0:
@@ -341,19 +375,20 @@ def _make_scheduled_jobs(context, data_dict):
         data_dict = {'source_id': source.id}
         try:
             get_action('harvest_job_create')(context, data_dict)
-        except HarvestJobExists, e:
+        except HarvestJobExists:
             log.info('Trying to rerun job for %s skipping' % source.id)
 
-        source.next_run = _caluclate_next_run(source.frequency)
+        source.next_run = _calculate_next_run(source.frequency)
         source.save()
 
-def harvest_jobs_run(context,data_dict):
+
+def harvest_jobs_run(context, data_dict):
     log.info('Harvest job run: %r', data_dict)
-    check_access('harvest_jobs_run',context,data_dict)
+    check_access('harvest_jobs_run', context, data_dict)
 
     session = context['session']
 
-    source_id = data_dict.get('source_id',None)
+    source_id = data_dict.get('source_id')
 
     if not source_id:
         _make_scheduled_jobs(context, data_dict)
@@ -361,38 +396,41 @@ def harvest_jobs_run(context,data_dict):
     context['return_objects'] = False
 
     # Flag finished jobs as such
-    jobs = harvest_job_list(context,{'source_id':source_id,'status':u'Running'})
+    jobs = harvest_job_list(
+        context, {'source_id': source_id, 'status': u'Running'})
     if len(jobs):
         for job in jobs:
             if job['gather_finished']:
-                objects = session.query(HarvestObject.id) \
-                          .filter(HarvestObject.harvest_job_id==job['id']) \
-                          .filter(and_((HarvestObject.state!=u'COMPLETE'),
-                                       (HarvestObject.state!=u'ERROR'))) \
-                          .order_by(HarvestObject.import_finished.desc())
+                objects = \
+                    session.query(HarvestObject.id) \
+                           .filter(HarvestObject.harvest_job_id == job['id']) \
+                           .filter(and_((HarvestObject.state != u'COMPLETE'),
+                                        (HarvestObject.state != u'ERROR'))) \
+                           .order_by(HarvestObject.import_finished.desc())
 
                 if objects.count() == 0:
                     job_obj = HarvestJob.get(job['id'])
                     job_obj.status = u'Finished'
 
                     last_object = session.query(HarvestObject) \
-                          .filter(HarvestObject.harvest_job_id==job['id']) \
-                          .filter(HarvestObject.import_finished!=None) \
-                          .order_by(HarvestObject.import_finished.desc()) \
-                          .first()
+                        .filter(HarvestObject.harvest_job_id == job['id']) \
+                        .filter(HarvestObject.import_finished != None) \
+                        .order_by(HarvestObject.import_finished.desc()) \
+                        .first()
                     if last_object:
                         job_obj.finished = last_object.import_finished
                     job_obj.save()
                     # Reindex the harvest source dataset so it has the latest
                     # status
-                    get_action('harvest_source_reindex')(context,
-                        {'id': job_obj.source.id})
+                    get_action('harvest_source_reindex')(
+                        context, {'id': job_obj.source.id})
 
     # resubmit old redis tasks
     resubmit_jobs()
 
     # Check if there are pending harvest jobs
-    jobs = harvest_job_list(context,{'source_id':source_id,'status':u'New'})
+    jobs = harvest_job_list(
+        context, {'source_id': source_id, 'status': u'New'})
     if len(jobs) == 0:
         log.info('No new harvest jobs.')
         raise NoNewHarvestJobError('There are no new harvesting jobs')
@@ -402,7 +440,7 @@ def harvest_jobs_run(context,data_dict):
     sent_jobs = []
     for job in jobs:
         context['detailed'] = False
-        source = harvest_source_show(context,{'id':job['source_id']})
+        source = harvest_source_show(context, {'id': job['source_id']})
         if source['active']:
             job_obj = HarvestJob.get(job['id'])
             job_obj.status = job['status'] = u'Running'
@@ -431,7 +469,7 @@ def harvest_job_abort(context, data_dict):
 
     model = context['model']
 
-    source_id = data_dict.get('source_id', None)
+    source_id = data_dict.get('source_id')
     source = harvest_source_show(context, {'id': source_id})
 
     # HarvestJob set status to 'Finished'
@@ -484,20 +522,22 @@ def harvest_sources_reindex(context, data_dict):
     model = context['model']
 
     packages = model.Session.query(model.Package) \
-                            .filter(model.Package.type==DATASET_TYPE_NAME) \
-                            .filter(model.Package.state==u'active') \
+                            .filter(model.Package.type == DATASET_TYPE_NAME) \
+                            .filter(model.Package.state == u'active') \
                             .all()
 
     package_index = PackageSearchIndex()
 
     reindex_context = {'defer_commit': True}
     for package in packages:
-        get_action('harvest_source_reindex')(reindex_context, {'id': package.id})
+        get_action('harvest_source_reindex')(
+            reindex_context, {'id': package.id})
 
     package_index.commit()
 
     return True
 
+
 @logic.side_effect_free
 def harvest_source_reindex(context, data_dict):
     '''Reindex a single harvest source'''
@@ -508,8 +548,8 @@ def harvest_source_reindex(context, data_dict):
     if 'extras_as_string'in context:
         del context['extras_as_string']
     context.update({'ignore_auth': True})
-    package_dict = logic.get_action('harvest_source_show')(context,
-        {'id': harvest_source_id})
+    package_dict = logic.get_action('harvest_source_show')(
+        context, {'id': harvest_source_id})
     log.debug('Updating search index for harvest source: {0}'.format(
         package_dict.get('name') or harvest_source_id))
 
diff --git a/ckanext/harvest/logic/validators.py b/ckanext/harvest/logic/validators.py
index 4dec758..d12be67 100644
--- a/ckanext/harvest/logic/validators.py
+++ b/ckanext/harvest/logic/validators.py
@@ -14,22 +14,25 @@ from ckan.lib.navl.validators import keep_extras
 
 log = logging.getLogger(__name__)
 
+
 def harvest_source_id_exists(value, context):
 
-    result = HarvestSource.get(value,None)
+    result = HarvestSource.get(value)
 
     if not result:
         raise Invalid('Harvest Source with id %r does not exist.' % str(value))
     return value
 
+
 def harvest_job_exists(value, context):
-    """Check if a harvest job exists and returns the model if it does"""
-    result = HarvestJob.get(value, None)
+    '''Check if a harvest job exists and returns the model if it does'''
+    result = HarvestJob.get(value)
 
     if not result:
         raise Invalid('Harvest Job with id %r does not exist.' % str(value))
     return result
 
+
 def _normalize_url(url):
     o = urlparse.urlparse(url)
 
@@ -48,60 +51,81 @@ def _normalize_url(url):
     path = o.path.rstrip('/')
 
     check_url = urlparse.urlunparse((
-            o.scheme,
-            netloc,
-            path,
-            None,None,None))
+        o.scheme,
+        netloc,
+        path,
+        None, None, None))
 
     return check_url
 
-def harvest_source_url_validator(key,data,errors,context):
-    package = context.get("package")
+
+def harvest_source_url_validator(key, data, errors, context):
+    '''Validate the provided harvest source URL
+
+    Checks that the URL & config combination are unique to this HarvestSource.
+    '''
+
+    package = context.get('package')
 
     if package:
         package_id = package.id
     else:
-        package_id = data.get(key[:-1] + ("id",))
+        package_id = data.get(key[:-1] + ('id',))
+
+    try:
+        new_config = data.get(key[:-1] + ('config',))
+    except:
+        new_config = None
 
     new_url = _normalize_url(data[key])
-    #pkg_id = data.get(('id',),'')
 
-    q = model.Session.query(model.Package.url, model.Package.state) \
-               .filter(model.Package.type==DATASET_TYPE_NAME)
+    q = model.Session.query(model.Package.id, model.Package.url) \
+             .filter(model.Package.type == DATASET_TYPE_NAME)
 
     if package_id:
         # When editing a source we need to avoid its own URL
-        q = q.filter(model.Package.id!=package_id)
+        q = q.filter(model.Package.id != package_id)
 
     existing_sources = q.all()
 
-    for url, state in existing_sources:
+    for id_, url in existing_sources:
         url = _normalize_url(url)
-        if url == new_url:
-            raise Invalid('There already is a Harvest Source for this URL: %s' % data[key])
+        conf = model.Session.query(HarvestSource.config).filter(
+            HarvestSource.id == id_).first()
+        if conf:
+            conf = conf[0]
+        else:
+            conf = None
+
+        if url == new_url and conf == new_config:
+            raise Invalid('There already is a Harvest Source for this URL (& '
+                          'config): url=%s config=%s' % (new_url, new_config))
 
     return data[key]
 
-def harvest_source_type_exists(value,context):
-    #TODO: use new description interface
+
+def harvest_source_type_exists(value, context):
+    # TODO: use new description interface
 
     # Get all the registered harvester types
     available_types = []
     for harvester in PluginImplementations(IHarvester):
         info = harvester.info()
         if not info or 'name' not in info:
-            log.error('Harvester %r does not provide the harvester name in the info response' % str(harvester))
+            log.error('Harvester %s does not provide the harvester name in '
+                      'the info response' % harvester)
             continue
         available_types.append(info['name'])
 
-
     if not value in available_types:
-        raise Invalid('Unknown harvester type: %s. Have you registered a harvester for this type?' % value)
+        raise Invalid('Unknown harvester type: %s. Have you registered a '
+                      'harvester for this type?' % value)
 
     return value
 
-def harvest_source_config_validator(key,data,errors,context):
-    harvester_type = data.get(('source_type',),'')
+
+def harvest_source_config_validator(key, data, errors, context):
+    harvester_type = data.get(('source_type',), '')
     for harvester in PluginImplementations(IHarvester):
         info = harvester.info()
         if info['name'] == harvester_type:
@@ -109,21 +133,24 @@ def harvest_source_config_validator(key,data,errors,context):
                 try:
                     return harvester.validate_config(data[key])
                 except Exception, e:
-                    raise Invalid('Error parsing the configuration options: %s' % str(e))
+                    raise Invalid('Error parsing the configuration options: %s'
+                                  % e)
             else:
                 return data[key]
 
+
 def keep_not_empty_extras(key, data, errors, context):
     extras = data.pop(key, {})
     for extras_key, value in extras.iteritems():
         if value:
             data[key[:-1] + (extras_key,)] = value
 
-def harvest_source_extra_validator(key,data,errors,context):
-    harvester_type = data.get(('source_type',),'')
 
-    #gather all extra fields to use as whitelist of what
-    #can be added to top level data_dict
+def harvest_source_extra_validator(key, data, errors, context):
+    harvester_type = data.get(('source_type',), '')
+
+    # gather all extra fields to use as whitelist of what
+    # can be added to top level data_dict
     all_extra_fields = set()
     for harvester in PluginImplementations(IHarvester):
         if not hasattr(harvester, 'extra_schema'):
@@ -142,7 +169,7 @@ def harvest_source_extra_validator(key,data,errors,context):
 
     extra_data, extra_errors = validate(data.get(key, {}), extra_schema)
     for key in extra_data.keys():
-        #only allow keys that appear in at least one harvester
+        # only allow keys that appear in at least one harvester
         if key not in all_extra_fields:
             extra_data.pop(key)
 
@@ -152,8 +179,8 @@ def harvest_source_extra_validator(key,data,errors,context):
     for key, value in extra_errors.iteritems():
         errors[(key,)] = value
 
-    ## need to get config out of extras as __extra runs
-    ## after rest of validation
+    # need to get config out of extras as __extra runs
+    # after rest of validation
     package_extras = data.get(('extras',), [])
 
     for num, extra in enumerate(list(package_extras)):
@@ -177,21 +204,24 @@ def harvest_source_extra_validator(key,data,errors,context):
     if package_extras:
         data[('extras',)] = package_extras
 
-def harvest_source_convert_from_config(key,data,errors,context):
+
+def harvest_source_convert_from_config(key, data, errors, context):
     config = data[key]
     if config:
         config_dict = json.loads(config)
         for key, value in config_dict.iteritems():
             data[(key,)] = value
 
-def harvest_source_active_validator(value,context):
-    if isinstance(value,basestring):
+
+def harvest_source_active_validator(value, context):
+    if isinstance(value, basestring):
         if value.lower() == 'true':
             return True
         else:
             return False
     return bool(value)
 
+
 def harvest_source_frequency_exists(value):
     if value == '':
         value = 'MANUAL'
@@ -205,6 +235,7 @@ def dataset_type_exists(value):
         value = DATASET_TYPE_NAME
     return value
 
+
 def harvest_object_extras_validator(value, context):
     if not isinstance(value, dict):
         raise Invalid('extras must be a dict')
diff --git a/ckanext/harvest/tests/test_action.py b/ckanext/harvest/tests/test_action.py
index 7aed649..24127b0 100644
--- a/ckanext/harvest/tests/test_action.py
+++ b/ckanext/harvest/tests/test_action.py
@@ -2,6 +2,7 @@ import json
 import copy
 import factories
 import unittest
+from nose.tools import assert_equal, assert_raises
 
 try:
     from ckan.tests import factories as ckan_factories
@@ -12,6 +13,7 @@ except ImportError:
 from ckan import plugins as p
 from ckan.plugins import toolkit
 from ckan import model
+import ckan.lib.search as search
 
 from ckanext.harvest.interfaces import IHarvester
 import ckanext.harvest.model as harvest_model
@@ -127,6 +129,32 @@ class FunctionalTestBaseWithoutClearBetweenTests(object):
         pass
 
 
+SOURCE_DICT = {
+    "url": "http://test.action.com",
+    "name": "test-source-action",
+    "title": "Test source action",
+    "notes": "Test source action desc",
+    "source_type": "test-for-action",
+    "frequency": "MANUAL",
+    "config": json.dumps({"custom_option": ["a", "b"]})
+}
+
+
+class ActionBase(object):
+    @classmethod
+    def setup_class(cls):
+        if not p.plugin_loaded('test_action_harvester'):
+            p.load('test_action_harvester')
+
+    def setup(self):
+        reset_db()
+        harvest_model.setup()
+
+    @classmethod
+    def teardown_class(cls):
+        p.unload('test_action_harvester')
+
+
 class HarvestSourceActionBase(FunctionalTestBaseWithoutClearBetweenTests):
 
     @classmethod
@@ -136,15 +164,7 @@ class HarvestSourceActionBase(FunctionalTestBaseWithoutClearBetweenTests):
 
         cls.sysadmin = ckan_factories.Sysadmin()
 
-        cls.default_source_dict = {
-            "url": "http://test.action.com",
-            "name": "test-source-action",
-            "title": "Test source action",
-            "notes": "Test source action desc",
-            "source_type": "test-for-action",
-            "frequency": "MANUAL",
-            "config": json.dumps({"custom_option": ["a", "b"]})
-        }
+        cls.default_source_dict = SOURCE_DICT
 
         if not p.plugin_loaded('test_action_harvester'):
             p.load('test_action_harvester')
@@ -287,6 +307,69 @@ class TestHarvestSourceActionUpdate(HarvestSourceActionBase):
         assert source.type == source_dict['source_type']
 
 
+class TestActions(ActionBase):
+    def test_harvest_source_clear(self):
+        source = factories.HarvestSourceObj(**SOURCE_DICT)
+        job = factories.HarvestJobObj(source=source)
+        dataset = ckan_factories.Dataset()
+        object_ = factories.HarvestObjectObj(job=job, source=source,
+                                             package_id=dataset['id'])
+
+        context = {'model': model, 'session': model.Session,
+                   'ignore_auth': True, 'user': ''}
+        result = toolkit.get_action('harvest_source_clear')(
+            context, {'id': source.id})
+
+        assert_equal(result, {'id': source.id})
+        source = harvest_model.HarvestSource.get(source.id)
+        assert source
+        assert_equal(harvest_model.HarvestJob.get(job.id), None)
+        assert_equal(harvest_model.HarvestObject.get(object_.id), None)
+        assert_equal(model.Package.get(dataset['id']), None)
+
+    def test_harvest_source_create_twice_with_unique_url(self):
+        # don't use factory because it looks for the existing source
+        data_dict = SOURCE_DICT
+        site_user = toolkit.get_action('get_site_user')(
+            {'model': model, 'ignore_auth': True}, {})['name']
+
+        toolkit.get_action('harvest_source_create')(
+            {'user': site_user}, data_dict)
+
+        data_dict['name'] = 'another-source1'
+        data_dict['url'] = 'http://another-url'
+        toolkit.get_action('harvest_source_create')(
+            {'user': site_user}, data_dict)
+
+    def test_harvest_source_create_twice_with_same_url(self):
+        # don't use factory because it looks for the existing source
+        data_dict = SOURCE_DICT
+        site_user = toolkit.get_action('get_site_user')(
+            {'model': model, 'ignore_auth': True}, {})['name']
+
+        toolkit.get_action('harvest_source_create')(
+            {'user': site_user}, data_dict)
+
+        data_dict['name'] = 'another-source2'
+        assert_raises(toolkit.ValidationError,
+                      toolkit.get_action('harvest_source_create'),
+                      {'user': site_user}, data_dict)
+
+    def test_harvest_source_create_twice_with_unique_url_and_config(self):
+        # don't use factory because it looks for the existing source
+        data_dict = SOURCE_DICT
+        site_user = toolkit.get_action('get_site_user')(
+            {'model': model, 'ignore_auth': True}, {})['name']
+
+        toolkit.get_action('harvest_source_create')(
+            {'user': site_user}, data_dict)
+
+        data_dict['name'] = 'another-source3'
+        data_dict['config'] = '{"something": "new"}'
+        toolkit.get_action('harvest_source_create')(
+            {'user': site_user}, data_dict)
+
+
 class TestHarvestObject(unittest.TestCase):
     @classmethod
     def setup_class(cls):