Render certificate templates in the correct language

LEARNER-2921

lms/djangoapps/certificates/api.py

@@ -503,7 +503,7 @@ def get_certificate_template(course_key, mode, language):
             mode=mode
         )
         template = get_language_specific_template_or_default(language, mode_templates)
-    return template.template if template else None
+    return template if template else None
 
 
 def get_language_specific_template_or_default(language, templates):
@@ -540,7 +540,12 @@ def _get_two_letter_language_code(language_code):
     Shortens language to only first two characters (e.g. es-419 becomes es)
     This is needed because Catalog returns locale language which is not always a 2 letter code.
     """
-    return language_code[:2] if language_code else None
+    if language_code is None:
+        return None
+    elif language_code == '':
+        return ''
+    else:
+        return language_code[:2]
 
 
 def emit_certificate_event(event_name, user, course_id, course=None, event_data=None):

lms/djangoapps/certificates/tests/test_webview_views.py

@@ -41,6 +41,7 @@ from lms.djangoapps.badges.tests.factories import (
 )
 from lms.djangoapps.grades.tests.utils import mock_passing_grade
 from openedx.core.djangoapps.certificates.config import waffle
+from openedx.core.djangoapps.dark_lang.models import DarkLangConfig
 from openedx.core.lib.tests.assertions.events import assert_event_matches
 from student.roles import CourseStaffRole
 from student.tests.factories import CourseEnrollmentFactory, UserFactory
@@ -1079,6 +1080,8 @@ class CertificatesViewsTests(CommonCertificatesTestCase):
         Tests custom template search and rendering.
         This test should check template matching when org={org}, course={course}, mode={mode}.
         """
+        DarkLangConfig(released_languages='es-419, fr', changed_by=self.user, enabled=True).save()
+
         right_language = 'es'
         wrong_language = 'fr'
         mock_get_org_id.return_value = 1
@@ -1137,6 +1140,8 @@ class CertificatesViewsTests(CommonCertificatesTestCase):
         match org and mode.
         This test should check template matching when org={org}, course=Null, mode={mode}.
         """
+        DarkLangConfig(released_languages='es-419, fr', changed_by=self.user, enabled=True).save()
+
         right_language = 'es'
         wrong_language = 'fr'
         mock_get_org_id.return_value = 1
@@ -1193,6 +1198,8 @@ class CertificatesViewsTests(CommonCertificatesTestCase):
         Tests custom template search when we have a single template for a organization.
         This test should check template matching when org={org}, course=Null, mode=null.
         """
+        DarkLangConfig(released_languages='es-419, fr', changed_by=self.user, enabled=True).save()
+
         right_language = 'es'
         wrong_language = 'fr'
         mock_get_org_id.return_value = 1
@@ -1248,6 +1255,8 @@ class CertificatesViewsTests(CommonCertificatesTestCase):
         Tests custom template search if we have a single template for a course mode.
         This test should check template matching when org=null, course=Null, mode={mode}.
         """
+        DarkLangConfig(released_languages='es-419, fr', changed_by=self.user, enabled=True).save()
+
         right_language = 'es'
         wrong_language = 'fr'
         mock_get_org_id.return_value = 1
@@ -1303,6 +1312,8 @@ class CertificatesViewsTests(CommonCertificatesTestCase):
         Tests custom template search if we have a single template for a course mode.
         This test should check template matching when org=null, course=Null, mode={mode}.
         """
+        DarkLangConfig(released_languages='es-419, fr', changed_by=self.user, enabled=True).save()
+
         right_language = 'es'
         wrong_language = 'fr'
         mock_get_org_id.return_value = 1