persist_letter saves address correctly to database

the `to` field stores either the phone number or the email address
of the recipient - it's a bit more complicated for letters, since
there are address lines 1 through 6, and a postcode. In utils, they're
stored alongside the personalisation, and we have to ensure that when
we persist to the database we keep as much parity with utils to make
our work easier. Aside from sending, the `to` field is also used to
show recipients on the front end report pages - we've decided that the
best thing to store here is address_line_1 - which is probably going to
be either a person's name, company name, or PO box number

Also, a lot of tests and test cleanup - I added create_template and
create_notification functions in db.py, so if you're creating new
fixtures you can use these functions, and you won't need to pass
notify_db and notify_db_session around, huzzah!

also removed create param from sample_notification since it's not used
anywhere

tests/app/conftest.py

@@ -25,7 +25,7 @@ from app.models import (
     NotificationStatistics,
     ServiceWhitelist,
     KEY_TYPE_NORMAL, KEY_TYPE_TEST, KEY_TYPE_TEAM,
-    MOBILE_TYPE, EMAIL_TYPE, NOTIFICATION_STATUS_TYPES_COMPLETED)
+    MOBILE_TYPE, EMAIL_TYPE, LETTER_TYPE, NOTIFICATION_STATUS_TYPES_COMPLETED)
 from app.dao.users_dao import (create_user_code, create_secret_code)
 from app.dao.services_dao import (dao_create_service, dao_add_user_to_service)
 from app.dao.templates_dao import dao_create_template
@@ -35,12 +35,8 @@ from app.dao.notifications_dao import dao_create_notification
 from app.dao.invited_user_dao import save_invited_user
 from app.dao.provider_rates_dao import create_provider_rates
 from app.clients.sms.firetext import FiretextClient
-from app.dao.provider_details_dao import (
-    dao_update_provider_details,
-    get_provider_details_by_identifier,
-    get_alternative_sms_provider
-)
-from tests.app.db import create_user
+
+from tests.app.db import create_user, create_template, create_notification
 
 
 @pytest.yield_fixture
@@ -228,6 +224,11 @@ def sample_email_template(
     return template
 
 
+@pytest.fixture
+def sample_letter_template(sample_service):
+    return create_template(sample_service, template_type=LETTER_TYPE)
+
+
 @pytest.fixture(scope='function')
 def sample_email_template_with_placeholders(notify_db, notify_db_session):
     return sample_email_template(
@@ -363,6 +364,24 @@ def sample_email_job(notify_db,
     return job
 
 
+@pytest.fixture
+def sample_letter_job(sample_service, sample_letter_template):
+    data = {
+        'id': uuid.uuid4(),
+        'service_id': sample_service.id,
+        'service': sample_service,
+        'template_id': sample_letter_template.id,
+        'template_version': sample_letter_template.version,
+        'original_file_name': 'some.csv',
+        'notification_count': 1,
+        'created_at': datetime.utcnow(),
+        'created_by': sample_service.created_by,
+    }
+    job = Job(**data)
+    dao_create_job(job)
+    return job
+
+
 @pytest.fixture(scope='function')
 def sample_notification_with_job(
         notify_db,
@@ -377,7 +396,6 @@ def sample_notification_with_job(
         created_at=None,
         sent_at=None,
         billable_units=1,
-        create=True,
         personalisation=None,
         api_key_id=None,
         key_type=KEY_TYPE_NORMAL
@@ -398,7 +416,6 @@ def sample_notification_with_job(
         created_at=created_at,
         sent_at=sent_at,
         billable_units=billable_units,
-        create=create,
         personalisation=personalisation,
         api_key_id=api_key_id,
         key_type=key_type
@@ -418,7 +435,6 @@ def sample_notification(notify_db,
                         created_at=None,
                         sent_at=None,
                         billable_units=1,
-                        create=True,
                         personalisation=None,
                         api_key_id=None,
                         key_type=KEY_TYPE_NORMAL,
@@ -464,11 +480,22 @@ def sample_notification(notify_db,
     if job_row_number:
         data['job_row_number'] = job_row_number
     notification = Notification(**data)
-    if create:
-        dao_create_notification(notification)
+    dao_create_notification(notification)
     return notification
 
 
+@pytest.fixture
+def sample_letter_notification(sample_letter_template):
+    address = {
+        'addressline1': 'A1',
+        'addressline2': 'A2',
+        'addressline3': 'A3',
+        'addressline4': 'A4',
+        'postcode': 'A_POST'
+    }
+    return create_notification(sample_letter_template, personalisation=address)
+
+
 @pytest.fixture(scope='function')
 def sample_notification_with_api_key(notify_db, notify_db_session):
     notification = sample_notification(notify_db, notify_db_session)