Fix another issue with line order on unified diffs

Summary: This improves some cases with interleaved added and removed lines, and adds test coverage.

Test Plan:
  - Added and executed unit tests.
  - Viewed raw diff and saw sensible/expected output.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Differential Revision: https://secure.phabricator.com/D11992

src/applications/differential/__tests__/data/order.diff

@@ -0,0 +1,24 @@
+diff --git a/src/applications/conpherence/controller/ConpherenceUpdateController b/src/applications/conpherence/controller/ConpherenceUpdateController
+--- a/src/applications/conpherence/controller/ConpherenceUpdateController
++++ b/src/applications/conpherence/controller/ConpherenceUpdateController
+@@ -209,14 +209,19 @@
+         ->setDatasource(new PhabricatorPeopleDatasource()));
+
+     require_celerity_resource('conpherence-update-css');
+-    return id(new AphrontDialogView())
++    $view = id(new AphrontDialogView())
+       ->setTitle(pht('Add Participants'))
+       ->addHiddenInput('action', 'add_person')
+       ->addHiddenInput(
+         'latest_transaction_id',
+         $request->getInt('latest_transaction_id'))
+       ->appendChild($form);
++
++    if ($request->getExists('minimal_display')) {
++      $view->addHiddenInput('minimal_display', true);
+     }
++    return $view;
++  }
+
+   private function renderRemovePersonDialogue(
+     ConpherenceThread $conpherence) {

src/applications/differential/__tests__/data/order.diff.one.expect

@@ -0,0 +1,26 @@
+CTYPE 2 1 (unforced)
+src/applications/conpherence/controller/ConpherenceUpdateController
+src/applications/conpherence/controller/ConpherenceUpdateController
+-
+X <MISSING-CONTEXT>
+N 209 .         ->setDatasource(new PhabricatorPeopleDatasource()));\n~
+N 210 . \n~
+N 211 .     require_celerity_resource('conpherence-update-css');\n~
+O 212 -     {(return)} id(new AphrontDialogView())\n~
+N 212 +     {($view =)} id(new AphrontDialogView())\n~
+N 213 .       ->setTitle(pht('Add Participants'))\n~
+N 214 .       ->addHiddenInput('action', 'add_person')\n~
+N 215 .       ->addHiddenInput(\n~
+N 216 .         'latest_transaction_id',\n~
+N 217 .         $request->getInt('latest_transaction_id'))\n~
+N 218 .       ->appendChild($form);\n~
+N 219 + \n~
+N 220 +     if ($request->getExists('minimal_display')) {\n~
+N 221 +       $view->addHiddenInput('minimal_display', true);\n~
+N 222 .     }\n~
+N 223 +     return $view;\n~
+N 224 +   }\n~
+N 225 . \n~
+N 226 .   private function renderRemovePersonDialogue(\n~
+N 227 .     ConpherenceThread $conpherence) {\n~
+X <MISSING-CONTEXT>

src/applications/differential/__tests__/data/order.diff.two.expect

@@ -0,0 +1,44 @@
+CTYPE 2 1 (unforced)
+src/applications/conpherence/controller/ConpherenceUpdateController
+src/applications/conpherence/controller/ConpherenceUpdateController
+-
+X <MISSING-CONTEXT>
+O 209 .         ->setDatasource(new PhabricatorPeopleDatasource()));\n~
+N 209 .         ->setDatasource(new PhabricatorPeopleDatasource()));\n~
+O 210 . \n~
+N 210 . \n~
+O 211 .     require_celerity_resource('conpherence-update-css');\n~
+N 211 .     require_celerity_resource('conpherence-update-css');\n~
+O 212 -     {(return)} id(new AphrontDialogView())\n~
+N 212 +     {($view =)} id(new AphrontDialogView())\n~
+O 213 .       ->setTitle(pht('Add Participants'))\n~
+N 213 .       ->setTitle(pht('Add Participants'))\n~
+O 214 .       ->addHiddenInput('action', 'add_person')\n~
+N 214 .       ->addHiddenInput('action', 'add_person')\n~
+O 215 .       ->addHiddenInput(\n~
+N 215 .       ->addHiddenInput(\n~
+O 216 .         'latest_transaction_id',\n~
+N 216 .         'latest_transaction_id',\n~
+O 217 .         $request->getInt('latest_transaction_id'))\n~
+N 217 .         $request->getInt('latest_transaction_id'))\n~
+O 218 .       ->appendChild($form);\n~
+N 218 .       ->appendChild($form);\n~
+O - . ~
+N 219 + \n~
+O - . ~
+N 220 +     if ($request->getExists('minimal_display')) {\n~
+O - . ~
+N 221 +       $view->addHiddenInput('minimal_display', true);\n~
+O 219 .     }\n~
+N 222 .     }\n~
+O - . ~
+N 223 +     return $view;\n~
+O - . ~
+N 224 +   }\n~
+O 220 . \n~
+N 225 . \n~
+O 221 .   private function renderRemovePersonDialogue(\n~
+N 226 .   private function renderRemovePersonDialogue(\n~
+O 222 .     ConpherenceThread $conpherence) {\n~
+N 227 .     ConpherenceThread $conpherence) {\n~
+X <MISSING-CONTEXT>

src/applications/differential/render/DifferentialChangesetRenderer.php

@@ -522,6 +522,13 @@ abstract class DifferentialChangesetRenderer {
           // If this line is the same in both versions of the file, put it in
           // the old line buffer. This makes sure inlines on old, unchanged
           // lines end up in the right place.
+
+          // First, we need to flush the new line buffer if there's anything
+          // in it.
+          if ($new_buf) {
+            $out[] = $new_buf;
+            $new_buf = array();
+          }
           $old_buf[] = $primitive;
         } else {
           $new_buf[] = $primitive;

src/applications/differential/render/DifferentialChangesetTestRenderer.php

@@ -92,12 +92,15 @@ abstract class DifferentialChangesetTestRenderer
             ),
             $render);
 
-          $render = html_entity_decode($render);
+          $render = html_entity_decode($render, ENT_QUOTES);
 
           $t = ($type == 'old') ? 'O' : 'N';
 
           $out[] = "{$t} {$num} {$htype} {$render}~";
           break;
+        case 'no-context':
+          $out[] = 'X <MISSING-CONTEXT>';
+          break;
         default:
           $out[] = $type;
           break;