Fix an issue where the Herald test console doesn't work with "Content source" rules

Summary:
Ref T13130. See PHI619. Currently, the Herald "Test Console" doesn't pass a "Content Source" to the adapter, so if any rules of the given type execute a "Content source" field rule, they'll fatal.

Provide a content source:

  - If possible, use the content source from the most recent transaction.
  - Otherwise, build a default "web" content source from the current request.

Test Plan:
  - Wrote a "When [content source][is][whatever]" rule for tasks.
  - Ran test console against a task.
  - Before: got a fatal trying to interact with the content source.
  - After: transcript reports sensible content source.
    - Also commented out the "xaction" logic to test the fallback behavior.

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T13130

Differential Revision: https://secure.phabricator.com/D19411

src/applications/herald/controller/HeraldTestConsoleController.php

@@ -38,8 +38,10 @@ final class HeraldTestConsoleController extends HeraldController {
 
     $object = $this->getTestObject();
     $adapter = $this->getTestAdapter();
+    $source = $this->newContentSource($object);
 
     $adapter
+      ->setContentSource($source)
       ->setIsNewObject(false)
       ->setActingAsPHID($viewer->getPHID())
       ->setViewer($viewer);
@@ -218,4 +220,29 @@ final class HeraldTestConsoleController extends HeraldController {
       ->appendChild($view);
   }
 
+  private function newContentSource($object) {
+    $viewer = $this->getViewer();
+
+    // Try using the content source associated with the most recent transaction
+    // on the object.
+
+    $query = PhabricatorApplicationTransactionQuery::newQueryForObject($object);
+
+    $xaction = $query
+      ->setViewer($viewer)
+      ->withObjectPHIDs(array($object->getPHID()))
+      ->setLimit(1)
+      ->setOrder('newest')
+      ->executeOne();
+    if ($xaction) {
+      return $xaction->getContentSource();
+    }
+
+    // If we couldn't find a transaction (which should be rare), fall back to
+    // building a new content source from the test console request itself.
+
+    $request = $this->getRequest();
+    return PhabricatorContentSource::newFromRequest($request);
+  }
+
 }