Fix branding api get_logo_url return value

lms/djangoapps/branding/api.py

@@ -367,18 +367,20 @@ def get_base_url(is_secure):
     return _absolute_url(is_secure=is_secure, url_path="")
 
 
-def get_logo_url():
+def get_logo_url(is_secure=True):
     """
     Return the url for the branded logo image to be used
+    Arguments:
+        is_secure (bool): If true, use HTTPS as the protocol.
     """
 
     # if the MicrositeConfiguration has a value for the logo_image_url
     # let's use that
     image_url = microsite.get_value('logo_image_url')
     if image_url:
-        return '{static_url}{image_url}'.format(
-            static_url=settings.STATIC_URL,
-            image_url=image_url
+        return _absolute_url_staticfile(
+            is_secure=is_secure,
+            name=image_url,
         )
 
     # otherwise, use the legacy means to configure this

lms/djangoapps/branding/tests/test_api.py

@@ -0,0 +1,23 @@
+# encoding: utf-8
+"""Tests of Branding API """
+
+from django.test import TestCase
+
+import mock
+from branding.api import get_logo_url
+
+
+class TestHeader(TestCase):
+    """Test API end-point for retrieving the header. """
+
+    def test_cdn_urls_for_logo(self):
+        # Ordinarily, we'd use `override_settings()` to override STATIC_URL,
+        # which is what the staticfiles storage backend is using to construct the URL.
+        # Unfortunately, other parts of the system are caching this value on module
+        # load, which can cause other tests to fail.  To ensure that this change
+        # doesn't affect other tests, we patch the `url()` method directly instead.
+        cdn_url = "http://cdn.example.com/static/image.png"
+        with mock.patch('branding.api.staticfiles_storage.url', return_value=cdn_url):
+            logo_url = get_logo_url()
+
+        self.assertEqual(logo_url, cdn_url)

lms/djangoapps/certificates/api.py

@@ -571,7 +571,7 @@ def get_certificate_header_context(is_secure=True):
     data returned should be customized according to the microsite settings
     """
     data = dict(
-        logo_src=branding_api.get_logo_url(),
+        logo_src=branding_api.get_logo_url(is_secure),
         logo_url=branding_api.get_base_url(is_secure),
     )
 

lms/templates/navigation.html

@@ -53,7 +53,7 @@ site_status_msg = get_site_status_msg(course_id)
     <h1 class="logo">
       <a href="${marketing_link('ROOT')}">
         <%block name="navigation_logo">
-            <img src="${static.url(branding_api.get_logo_url())}" alt="${_("{platform_name} Home Page").format(platform_name=static.get_platform_name())}"/>
+            <img src="${branding_api.get_logo_url(is_secure)}" alt="${_("{platform_name} Home Page").format(platform_name=static.get_platform_name())}"/>
         </%block>
       </a>
     </h1>