evalutils: add attachment(content, filename, content_type) helper (#27323)

To allow creating mail attachments easily, test contains an example
sending a full JSON export of a formdata.

tests/test_workflows.py

@@ -1,3 +1,4 @@
+import json
 import datetime
 import os
 import pytest
@@ -1257,6 +1258,23 @@ def test_email_attachments(pub, emails):
     assert emails.emails['foobar']['msg'].get_payload()[2].get_payload() == 'blah'
     assert len(emails.emails['foobar']['msg'].get_payload()) == 3
 
+    emails.empty()
+    sendmail.attachments = [
+        'utils.attachment(form.formdata.export_to_json(include_files=False))',
+        'utils.attachment(form.formdata.export_to_json(), content_type=\'application/json\')',
+    ]
+    sendmail.perform(formdata)
+    get_response().process_after_jobs()
+    assert emails.count() == 1
+    assert emails.emails['foobar']['msg'].is_multipart()
+    assert emails.emails['foobar']['msg'].get_content_subtype() == 'mixed'
+    assert emails.emails['foobar']['msg'].get_payload(0).get_content_type() == 'text/html'
+    assert emails.emails['foobar']['msg'].get_payload(1).get_content_type() == 'application/octet-stream'
+    assert emails.emails['foobar']['msg'].get_payload(2).get_content_type() == 'application/json'
+    payload1 = emails.emails['foobar']['msg'].get_payload(1)
+    payload2 = emails.emails['foobar']['msg'].get_payload(2)
+    assert json.loads(formdata.export_to_json(include_files=False)) == json.loads(payload1.get_payload(decode=True))
+    assert json.loads(formdata.export_to_json()) == json.loads(payload2.get_payload(decode=True))
 
 
 def test_webservice_call(http_requests, pub):

wcs/qommon/evalutils.py

@@ -118,6 +118,18 @@ def age_in_seconds(born, today=None):
     today = make_datetime(today)
     return datetime_delta(today, born).total_seconds()
 
+
 def add_days(date, count):
     '''Add the given number of days to date'''
     return make_date(date) + datetime.timedelta(days=count)
+
+
+def attachment(content, filename='', content_type='application/octet-stream'):
+    '''Serialize content as an attachment'''
+    import base64
+
+    return {
+        'filename': filename,
+        'content_type': content_type,
+        'b64_content': base64.b64encode(content),
+    }