Created a method to decide which colour to pass into the notifications-utils method to preview the template.

Removed the ServiceCreateEmailBranding form - it is identical to the other form.

app/main/forms.py

@@ -756,35 +756,6 @@ class ServiceUpdateEmailBranding(StripWhitespaceForm):
     file = FileField_wtf('Upload a PNG logo', validators=[FileAllowed(['png'], 'PNG Images only!')])
 
 
-class ServiceCreateEmailBranding(StripWhitespaceForm):
-
-    name = StringField('Name of brand')
-    text = StringField('Text')
-    domain = StringField('Domain')
-    colour = StringField(
-        'Colour',
-        render_kw={'onchange': 'update_colour(this)'},
-        validators=[
-            Regexp(regex="^$|^#(?:[0-9a-fA-F]{3}){1,2}$", message='Must be a valid color hex code')
-        ]
-    )
-    banner_colour = StringField(
-        'Banner colour',
-        render_kw={'onchange': 'update_colour(this)'},
-        validators=[
-            Regexp(regex="^$|^#(?:[0-9a-fA-F]{3}){1,2}$", message='Must be a valid color hex code')
-        ]
-    )
-    single_id_colour = StringField(
-        'Single identity colour',
-        render_kw={'onchange': 'update_colour(this)'},
-        validators=[
-            Regexp(regex="^$|^#(?:[0-9a-fA-F]{3}){1,2}$", message='Must be a valid color hex code')
-        ]
-    )
-    file = FileField_wtf('Upload a PNG logo', validators=[FileAllowed(['png'], 'PNG Images only!')])
-
-
 class CreateOrUpdateOrganisation(StripWhitespaceForm):
 
     name = StringField('Name', validators=[DataRequired()])

app/main/views/email_branding.py

@@ -4,7 +4,6 @@ from flask_login import login_required
 from app import email_branding_client
 from app.main import main
 from app.main.forms import (
-    ServiceCreateEmailBranding,
     ServiceSelectEmailBranding,
     ServiceUpdateEmailBranding,
 )
@@ -109,7 +108,7 @@ def update_email_branding(branding_id, logo=None):
 @login_required
 @user_is_platform_admin
 def create_email_branding(logo=None):
-    form = ServiceCreateEmailBranding()
+    form = ServiceUpdateEmailBranding()
 
     if form.validate_on_submit():
         if form.file.data:

app/main/views/index.py

@@ -78,6 +78,13 @@ def design_content():
     return render_template('views/design-patterns-content-guidance.html')
 
 
+def _set_colour(branding_style, email_branding):
+    if branding_style in ['both', 'org']:
+        return email_branding['single_id_colour'] or email_branding['colour']
+    elif branding_style == 'org_banner':
+        return email_branding['banner_colour'] or email_branding['colour']
+
+
 @main.route('/_email')
 def email_template():
     branding_type = request.args.get('branding_type', 'govuk')
@@ -91,8 +98,9 @@ def email_template():
         brand_banner = False
     else:
         email_branding = email_branding_client.get_email_branding(branding_style)['email_branding']
+        colour = _set_colour(branding_type, email_branding)
         brand_name = email_branding['text']
-        brand_colour = email_branding['colour']
+        brand_colour = colour
         brand_logo = 'https://{}/{}'.format(get_cdn_domain(), email_branding['logo'])
         govuk_banner = branding_type in ['govuk', 'both']
         brand_banner = branding_type == 'org_banner'

tests/app/main/views/test_email_preview.py

@@ -4,6 +4,8 @@ import pytest
 from bs4 import BeautifulSoup
 from flask import url_for
 
+from app.main.views.index import _set_colour
+
 
 @pytest.mark.parametrize(
     "query_args, result", [
@@ -86,7 +88,7 @@ def test_displays_org_branding_with_banner(client, mock_get_email_branding):
 
     assert not page.find("a", attrs={"href": "https://www.gov.uk"})
     assert page.find("img", attrs={"src": re.compile("example.png")})
-    assert page.select("body > table > tr > td[bgcolor='#f00']")  # banner colour is set
+    assert page.select("body > table > tr > td[bgcolor='#f11']")  # banner colour is set
     assert page.select("body > table table > tr > td > span")[0]\
         .get_text().strip() == 'Organisation text'  # brand text is set
 
@@ -104,5 +106,28 @@ def test_displays_org_branding_with_banner_without_brand_text(
 
     assert not page.find("a", attrs={"href": "https://www.gov.uk"})
     assert page.find("img", attrs={"src": re.compile("example.png")})
-    assert page.select("body > table > tr > td[bgcolor='#f00']")  # banner colour is set
+    assert page.select("body > table > tr > td[bgcolor='#f11']")  # banner colour is set
     assert not page.select("body > table table > tr > td > span") == 0  # brand text is not set
+
+
+@pytest.mark.parametrize('colour, banner_colour, single_id_colour, branding_type, expected_colour', [
+    ('black', 'yellow', 'red', 'org', 'red'),
+    ('black', 'yellow', None, 'org', 'black'),
+    ('black', 'yellow', 'red', 'org_banner', 'yellow'),
+    ('black', None, 'red', 'org_banner', 'black'),
+    ('black', 'yellow', 'red', 'govuk', None),
+    ('black', 'yellow', 'red', 'both', 'red'),
+    ('black', 'yellow', None, 'both', 'black'),
+])
+def test_set_colour(colour, banner_colour, single_id_colour, branding_type, expected_colour):
+    email_branding = {
+        'logo': None,
+        'colour': colour,
+        'text': 'new text',
+        'name': 'new name',
+        'domain': 'sample.com',
+        'banner_colour': banner_colour,
+        'single_id_colour': single_id_colour,
+    }
+    colour = _set_colour(branding_type, email_branding)
+    assert colour == expected_colour

tests/conftest.py

@@ -2514,7 +2514,9 @@ def mock_get_email_branding_without_brand_text(mocker, fake_uuid):
                 'name': 'Organisation name',
                 'text': '',
                 'id': fake_uuid,
-                'colour': '#f00'
+                'colour': '#f00',
+                'banner_colour': '#f11',
+                'single_id_colour': '#f22'
             }
         }