manager: display an error when importing a non-json file (#21056)

combo/manager/views.py

@@ -72,7 +72,12 @@ class SiteImportView(FormView):
     success_url = reverse_lazy('combo-manager-homepage')
 
     def form_valid(self, form):
-        json_site = json.load(self.request.FILES['site_json'])
+        try:
+            json_site = json.load(self.request.FILES['site_json'])
+        except ValueError:
+            form.add_error('site_json', _('File is not in the expected JSON format.'))
+            return self.form_invalid(form)
+
         try:
             import_site(json_site)
         except MissingGroups as e:

tests/test_manager.py

@@ -275,6 +275,13 @@ def test_site_export_import(app, admin_user):
     assert LinkCell.objects.get(page__slug='one').link_page.slug == 'two'
     assert LinkCell.objects.get(page__slug='two').link_page.slug == 'one'
 
+    # check with invalid file
+    resp = app.get('/manage/')
+    resp = resp.click('Import Site')
+    resp.form['site_json'] = Upload('site-export.json', 'invalid content', 'application/json')
+    resp = resp.form.submit()
+    assert 'File is not in the expected JSON format.' in resp.body
+
 def test_add_edit_cell(app, admin_user):
     Page.objects.all().delete()
     page = Page(title='One', slug='one', template_name='standard')