diff --git a/samples/pdfium_test.cc b/samples/pdfium_test.cc
index 91b4f90..26251fa 100644
--- a/samples/pdfium_test.cc
+++ b/samples/pdfium_test.cc
@@ -6,6 +6,7 @@
 #include <stdlib.h>
 #include <string.h>
 
+#include <functional>
 #include <iterator>
 #include <map>
 #include <memory>
@@ -730,12 +731,13 @@
                  FPDF_FORMFILLINFO_PDFiumTest* form_fill_info,
                  const int page_index,
                  const Options& options,
-                 const std::string& events) {
+                 const std::string& events,
+                 const std::function<void()>& idler) {
   FPDF_PAGE page = GetPageForIndex(form_fill_info, doc, page_index);
   if (!page)
     return false;
   if (options.send_events)
-    SendPageEvents(form, page, events);
+    SendPageEvents(form, page, events, idler);
   if (options.save_images)
     WriteImages(page, name.c_str(), page_index);
   if (options.save_rendered_images)
@@ -795,9 +797,12 @@
     }
 
     FPDF_FFLDraw(form, bitmap.get(), page, 0, 0, width, height, 0, flags);
+    idler();
 
-    if (!options.render_oneshot)
+    if (!options.render_oneshot) {
       FPDF_RenderPage_Close(page);
+      idler();
+    }
 
     int stride = FPDFBitmap_GetStride(bitmap.get());
     void* buffer = FPDFBitmap_GetBuffer(bitmap.get());
@@ -861,7 +866,11 @@
   }
 
   FORM_DoPageAAction(page, form, FPDFPAGE_AACTION_CLOSE);
+  idler();
+
   FORM_OnBeforeClosePage(page, form);
+  idler();
+
   return !!bitmap;
 }
 
@@ -869,7 +878,8 @@
                 const char* buf,
                 size_t len,
                 const Options& options,
-                const std::string& events) {
+                const std::string& events,
+                const std::function<void()>& idler) {
   TestLoader loader({buf, len});
 
   FPDF_FILEACCESS file_access = {};
@@ -1013,14 +1023,17 @@
       }
     }
     if (ProcessPage(name, doc.get(), form.get(), &form_callbacks, i, options,
-                    events)) {
+                    events, idler)) {
       ++processed_pages;
     } else {
       ++bad_pages;
     }
+    idler();
   }
 
   FORM_DoDocumentAAction(form.get(), FPDFDOC_AACTION_WC);
+  idler();
+
   fprintf(stderr, "Processed %d pages.\n", processed_pages);
   if (bad_pages)
     fprintf(stderr, "Skipped %d bad pages.\n", bad_pages);
@@ -1163,6 +1176,7 @@
   config.m_v8EmbedderSlot = 0;
   config.m_pPlatform = nullptr;
 
+  std::function<void()> idler = []() {};
 #ifdef PDF_ENABLE_V8
 #ifdef V8_USE_EXTERNAL_STARTUP_DATA
   v8::StartupData snapshot;
@@ -1187,6 +1201,14 @@
         FPDF_GetArrayBufferAllocatorSharedInstance());
     isolate.reset(v8::Isolate::New(params));
     config.m_pIsolate = isolate.get();
+
+    idler = [&platform, &isolate]() {
+      int task_count = 0;
+      while (v8::platform::PumpMessageLoop(platform.get(), isolate.get()))
+        ++task_count;
+      if (task_count)
+        fprintf(stderr, "Pumped %d tasks\n", task_count);
+    };
   }
 #endif  // PDF_ENABLE_V8
 
@@ -1245,18 +1267,10 @@
         }
       }
     }
-    ProcessPdf(filename, file_contents.get(), file_length, options, events);
 
-#ifdef PDF_ENABLE_V8
-    if (!options.disable_javascript) {
-      int task_count = 0;
-      while (v8::platform::PumpMessageLoop(platform.get(), isolate.get()))
-        ++task_count;
-
-      if (task_count)
-        fprintf(stderr, "Pumped %d tasks\n", task_count);
-    }
-#endif  // PDF_ENABLE_V8
+    ProcessPdf(filename, file_contents.get(), file_length, options, events,
+               idler);
+    idler();
 
 #ifdef ENABLE_CALLGRIND
     if (options.callgrind_delimiters)
diff --git a/samples/pdfium_test_event_helper.cc b/samples/pdfium_test_event_helper.cc
index 1fe30c3..292d5a1 100644
--- a/samples/pdfium_test_event_helper.cc
+++ b/samples/pdfium_test_event_helper.cc
@@ -156,7 +156,8 @@
 
 void SendPageEvents(FPDF_FORMHANDLE form,
                     FPDF_PAGE page,
-                    const std::string& events) {
+                    const std::string& events,
+                    const std::function<void()>& idler) {
   auto lines = StringSplit(events, '\n');
   for (const auto& line : lines) {
     auto command = StringSplit(line, '#');
@@ -182,5 +183,6 @@
     } else {
       fprintf(stderr, "Unrecognized event: %s\n", tokens[0].c_str());
     }
+    idler();
   }
 }
diff --git a/samples/pdfium_test_event_helper.h b/samples/pdfium_test_event_helper.h
index e823369..f03ddb9 100644
--- a/samples/pdfium_test_event_helper.h
+++ b/samples/pdfium_test_event_helper.h
@@ -5,6 +5,7 @@
 #ifndef SAMPLES_PDFIUM_TEST_EVENT_HELPER_H_
 #define SAMPLES_PDFIUM_TEST_EVENT_HELPER_H_
 
+#include <functional>
 #include <string>
 
 #include "public/fpdf_formfill.h"
@@ -12,6 +13,7 @@
 
 void SendPageEvents(FPDF_FORMHANDLE form,
                     FPDF_PAGE page,
-                    const std::string& events);
+                    const std::string& events,
+                    const std::function<void()>& idler);
 
 #endif  // SAMPLES_PDFIUM_TEST_EVENT_HELPER_H_
diff --git a/testing/resources/javascript/foreground_task.in b/testing/resources/javascript/foreground_task.in
index b96917c..dd5444a 100644
--- a/testing/resources/javascript/foreground_task.in
+++ b/testing/resources/javascript/foreground_task.in
@@ -30,8 +30,7 @@
 >>
 stream
 try {
-  // TODO(tsepez): figure out why .then() doesn't fire.
-  gc({type: 'major', execution: 'async'}).then(() => { app.alert('resolved') });
+  gc({type: 'major', execution: 'async'}).then(() => { app.alert('Resolved') });
   app.alert('Posted');
 } catch (e) {
   app.alert('Error: ' + e);
diff --git a/testing/resources/javascript/foreground_task_expected.txt b/testing/resources/javascript/foreground_task_expected.txt
index a561e88..d40e100 100644
--- a/testing/resources/javascript/foreground_task_expected.txt
+++ b/testing/resources/javascript/foreground_task_expected.txt
@@ -1 +1,2 @@
 Alert: Posted
+Alert: Resolved