- Refactoring of the mail sending part. Mail queue (table 'queued') is now used also for all test emails.

- More options how to send test emails.
- Fixed problems with pausing a campaign (#593)
- Started rework of transactional sender of templates (#606), however this contains functionality regression at the moment because it does not interpret templates as HBS. It needs HBS option for templates as described in https://github.com/Mailtrain-org/mailtrain/issues/611#issuecomment-502345227

TODO:
- detect sending errors connected to not able to contact the mailer and pause/retry campaing and queued sending - don't mark the recipients as BOUNCED
- add FAILED campaign state and fall into it if sending to campaign consistently fails (i.e. the error with sending is not temporary)
- if the same happends for queued email, delete the message

server/models/subscriptions.js

@@ -19,6 +19,8 @@ const lists = require('./lists');
 
 const allowedKeysBase = new Set(['email', 'tz', 'is_test', 'status']);
 
+const TEST_USERS_LIST_LIMIT = 1000;
+
 const fieldTypes = {};
 
 const Cardinality = {
@@ -409,6 +411,32 @@ async function list(context, listId, grouped, offset, limit) {
     });
 }
 
+async function listTestUsersTx(tx, context, listId, segmentId, grouped) {
+    await shares.enforceEntityPermissionTx(tx, context, 'list', listId, 'viewSubscriptions');
+
+    let entitiesQry = tx(getSubscriptionTableName(listId)).orderBy('id', 'asc').where('is_test', true).limit(TEST_USERS_LIST_LIMIT);
+
+    if (segmentId) {
+        const addSegmentQuery = await segments.getQueryGeneratorTx(tx, listId, segmentId);
+
+        entitiesQry = entitiesQry.where(function() {
+            addSegmentQuery(this);
+        });
+    }
+
+    const entities = await entitiesQry;
+
+    if (grouped) {
+        const groupedFieldsMap = await getGroupedFieldsMapTx(tx, listId);
+
+        for (const entity of entities) {
+            groupSubscription(groupedFieldsMap, entity);
+        }
+    }
+
+    return entities;
+}
+
 // Note that this does not do all the work in the transaction. Thus it is prone to fail if the list is deleted in during the run of the function
 async function* listIterator(context, listId, segmentId, grouped = true) {
     let groupedFieldsMap;
@@ -855,6 +883,7 @@ module.exports.getByEmail = getByEmail;
 module.exports.list = list;
 module.exports.listIterator = listIterator;
 module.exports.listDTAjax = listDTAjax;
+module.exports.listTestUsersTx = listTestUsersTx;
 module.exports.listTestUsersDTAjax = listTestUsersDTAjax;
 module.exports.serverValidate = serverValidate;
 module.exports.create = create;