Merge pull request #1918 from alphagov/letter_preview_use_api_not_template_preview

Letter preview use api not template preview

tests/app/main/views/test_notifications.py

@@ -1,9 +1,11 @@
+import base64
 from functools import partial
+from unittest.mock import mock_open
 
 import pytest
 from flask import url_for
 from freezegun import freeze_time
-from notifications_utils.template import LetterImageTemplate
+from notifications_python_client.errors import APIError
 from tests.conftest import (
     SERVICE_ONE_ID,
     mock_get_notification,
@@ -163,9 +165,11 @@ def test_should_show_image_of_letter_notification(
 
     mock_get_notification(mocker, fake_uuid, template_type='letter')
 
-    mocked_preview = mocker.patch(
-        'app.main.views.templates.TemplatePreview.from_utils_template',
-        return_value='foo'
+    mocker.patch(
+        'app.notify_client.notification_api_client.NotificationApiClient.get',
+        return_value={
+            'content': base64.b64encode(b'foo').decode('utf-8')
+        }
     )
 
     response = logged_in_client.get(url_for(
@@ -177,8 +181,32 @@ def test_should_show_image_of_letter_notification(
 
     assert response.status_code == 200
     assert response.get_data(as_text=True) == 'foo'
-    assert isinstance(mocked_preview.call_args[0][0], LetterImageTemplate)
-    assert mocked_preview.call_args[0][1] == filetype
+
+
+def test_should_show_preview_error_image_letter_notification_on_preview_error(
+    logged_in_client,
+    fake_uuid,
+    mocker,
+):
+
+    mock_get_notification(mocker, fake_uuid, template_type='letter')
+
+    mocker.patch(
+        'app.notify_client.notification_api_client.NotificationApiClient.get',
+        side_effect=APIError
+    )
+
+    mocker.patch("builtins.open", mock_open(read_data="preview error image"))
+
+    response = logged_in_client.get(url_for(
+        'main.view_letter_notification_as_preview',
+        service_id=SERVICE_ONE_ID,
+        notification_id=fake_uuid,
+        filetype='png'
+    ))
+
+    assert response.status_code == 200
+    assert response.get_data(as_text=True) == 'preview error image'
 
 
 def test_should_404_for_unknown_extension(