Go straight to add if no contact blocks yet

Same as previous commit, but for going forward, not back.

tests/app/main/views/test_templates.py

@@ -27,6 +27,7 @@ from tests.conftest import (
     ElementNotFound,
     active_caseworking_user,
     active_user_view_permissions,
+    fake_uuid,
     mock_get_service_email_template,
     mock_get_service_letter_template,
     mock_get_service_template,
@@ -687,17 +688,26 @@ def test_should_show_sms_template_with_downgraded_unicode_characters(
     assert rendered_msg in page.text
 
 
+@pytest.mark.parametrize('mock_contact_block, expected_partial_url', (
+    (no_letter_contact_blocks, partial(
+        url_for, 'main.service_add_letter_contact', from_template=fake_uuid(),
+    )),
+    (single_letter_contact_block, partial(
+        url_for, 'main.set_template_sender', template_id=fake_uuid(),
+    )),
+))
 def test_should_let_letter_contact_block_be_changed_for_the_template(
     mocker,
     mock_get_service_letter_template,
     mock_get_template_folders,
-    no_letter_contact_blocks,
     client_request,
     service_one,
     fake_uuid,
+    mock_contact_block,
+    expected_partial_url
 ):
-    service_one['permissions'].append('letter')
     mocker.patch('app.main.views.templates.get_page_count_for_letter', return_value=1)
+    mock_contact_block(mocker)
 
     page = client_request.get(
         'main.view_template',
@@ -706,11 +716,9 @@ def test_should_let_letter_contact_block_be_changed_for_the_template(
         _test_page_title=False,
     )
 
-    assert page.find('a', {'class': 'edit-template-link-letter-contact'})['href'] == url_for(
-        'main.set_template_sender',
-        service_id=SERVICE_ONE_ID,
-        template_id=fake_uuid,
-    )
+    assert page.select_one(
+        'a.edit-template-link-letter-contact'
+    )['href'] == expected_partial_url(service_id=SERVICE_ONE_ID)
 
 
 def test_should_show_page_template_with_priority_select_if_platform_admin(