Return rendered HTML when previewing a template

If you’re trying to show what a Notify email will look like in your
caseworking system all the API gives you at the moment is raw markdown
(with the placeholders replaced).

This isn’t that useful if your caseworkers have no idea what markdown
is. If we also give teams the HTML then they can embed this in their
systems, and the people using those systems will be able to see how
headings, bulleted lists, etc. look.

app/utils.py

@@ -3,7 +3,7 @@ from datetime import datetime, timedelta
 import pytz
 from flask import url_for
 from sqlalchemy import func
-from notifications_utils.template import SMSMessageTemplate, WithSubjectTemplate
+from notifications_utils.template import SMSMessageTemplate, WithSubjectTemplate, get_html_email_body
 from notifications_utils.timezones import convert_utc_to_bst
 
 local_timezone = pytz.timezone("Europe/London")
@@ -35,6 +35,18 @@ def get_template_instance(template, values):
     }[template['template_type']](template, values)
 
 
+def get_html_email_body_from_template(template_instance):
+    from app.models import EMAIL_TYPE
+
+    if template_instance.template_type != EMAIL_TYPE:
+        return None
+
+    return get_html_email_body(
+        template_instance.content,
+        template_instance.values,
+    )
+
+
 def get_london_midnight_in_utc(date):
     """
      This function converts date to midnight as BST (British Standard Time) to UTC,

app/v2/template/template_schemas.py

@@ -1,5 +1,6 @@
 from app.models import SMS_TYPE, TEMPLATE_TYPES
 from app.schema_validation.definitions import uuid, personalisation
+from app.utils import get_html_email_body_from_template
 
 
 get_template_by_id_request = {
@@ -79,6 +80,7 @@ def create_post_template_preview_response(template, template_object):
         "type": template.template_type,
         "version": template.version,
         "body": str(template_object),
+        "html": get_html_email_body_from_template(template_object),
         "subject": subject,
         "postage": template.postage
     }

tests/app/v2/template/test_post_template.py

@@ -2,7 +2,7 @@ import pytest
 
 from flask import json
 
-from app.models import SMS_TYPE, TEMPLATE_TYPES
+from app.models import EMAIL_TYPE, SMS_TYPE, TEMPLATE_TYPES
 from tests import create_authorization_header
 from tests.app.db import create_template
 
@@ -16,36 +16,68 @@ valid_post = [
         "Some content",
         None,
         "Some subject",
-        "Some content"
+        "Some content",
+        (
+            '<p style="Margin: 0 0 20px 0; font-size: 19px; line-height: 25px; color: #0B0C0C;">'
+            'Some content'
+            '</p>'
+        ),
     ),
     (
         "Some subject",
         "Dear ((Name)), Hello. Yours Truly, The Government.",
         valid_personalisation,
         "Some subject",
-        "Dear Jo, Hello. Yours Truly, The Government."
+        "Dear Jo, Hello. Yours Truly, The Government.",
+        (
+            '<p style="Margin: 0 0 20px 0; font-size: 19px; line-height: 25px; color: #0B0C0C;">'
+            'Dear Jo, Hello. Yours Truly, The Government.'
+            '</p>'
+        ),
     ),
     (
         "Message for ((Name))",
         "Dear ((Name)), Hello. Yours Truly, The Government.",
         valid_personalisation,
         "Message for Jo",
-        "Dear Jo, Hello. Yours Truly, The Government."
+        "Dear Jo, Hello. Yours Truly, The Government.",
+        (
+            '<p style="Margin: 0 0 20px 0; font-size: 19px; line-height: 25px; color: #0B0C0C;">'
+            'Dear Jo, Hello. Yours Truly, The Government.'
+            '</p>'
+        ),
     ),
     (
         "Message for ((Name))",
         "Some content",
         valid_personalisation,
         "Message for Jo",
-        "Some content"
+        "Some content",
+        (
+            '<p style="Margin: 0 0 20px 0; font-size: 19px; line-height: 25px; color: #0B0C0C;">'
+            'Some content'
+            '</p>'
+        ),
     ),
 ]
 
 
 @pytest.mark.parametrize("tmp_type", TEMPLATE_TYPES)
-@pytest.mark.parametrize("subject,content,post_data,expected_subject,expected_content", valid_post)
+@pytest.mark.parametrize(
+    "subject,content,post_data,expected_subject,expected_content,expected_html",
+    valid_post
+)
 def test_valid_post_template_returns_200(
-        client, sample_service, tmp_type, subject, content, post_data, expected_subject, expected_content):
+    client,
+    sample_service,
+    tmp_type,
+    subject,
+    content,
+    post_data,
+    expected_subject,
+    expected_content,
+    expected_html,
+):
     template = create_template(
         sample_service,
         template_type=tmp_type,
@@ -64,8 +96,15 @@ def test_valid_post_template_returns_200(
     resp_json = json.loads(response.get_data(as_text=True))
 
     assert resp_json['id'] == str(template.id)
+
     if tmp_type != SMS_TYPE:
         assert expected_subject in resp_json['subject']
+
+    if tmp_type == EMAIL_TYPE:
+        assert resp_json['html'] == expected_html
+    else:
+        assert resp_json['html'] is None
+
     assert expected_content in resp_json['body']