From 1a7b35b71802cb61a5d4558df709f2ea6545f6ae Mon Sep 17 00:00:00 2001
From: peter <peter@jetbrains.com>
Date: Mon, 12 Jun 2017 19:54:49 +0200
Subject: [PATCH] MemoryDiskConflictResolver: show the causing trace in tests

---
 .../fileEditor/impl/MemoryDiskConflictResolver.java   | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/platform/platform-impl/src/com/intellij/openapi/fileEditor/impl/MemoryDiskConflictResolver.java b/platform/platform-impl/src/com/intellij/openapi/fileEditor/impl/MemoryDiskConflictResolver.java
index 48ec4fa8297c..f89efbffc823 100644
--- a/platform/platform-impl/src/com/intellij/openapi/fileEditor/impl/MemoryDiskConflictResolver.java
+++ b/platform/platform-impl/src/com/intellij/openapi/fileEditor/impl/MemoryDiskConflictResolver.java
@@ -49,6 +49,7 @@ import java.util.Set;
 class MemoryDiskConflictResolver {
   private static final Logger LOG = Logger.getInstance("#com.intellij.openapi.fileEditor.impl.MemoryDiskConflictResolver");
   private final Set<VirtualFile> myConflicts = new LinkedHashSet<>();
+  private Throwable myConflictAppeared;
 
   void beforeContentChange(@NotNull VirtualFileEvent event) {
     if (event.isFromSave()) return;
@@ -66,6 +67,9 @@ class MemoryDiskConflictResolver {
       LOG.info("  documentStamp:" + documentStamp);
       LOG.info("  oldFileStamp:" + oldFileStamp);
       if (myConflicts.isEmpty()) {
+        if (ApplicationManager.getApplication().isUnitTestMode()) {
+          myConflictAppeared = new Throwable();
+        }
         ApplicationManager.getApplication().invokeLater(this::processConflicts);
       }
       myConflicts.add(file);
@@ -86,9 +90,16 @@ class MemoryDiskConflictResolver {
         FileDocumentManager.getInstance().reloadFromDisk(document);
       }
     }
+    myConflictAppeared = null;
   }
 
   boolean askReloadFromDisk(VirtualFile file, Document document) {
+    if (myConflictAppeared != null) {
+      Throwable trace = myConflictAppeared;
+      myConflictAppeared = null;
+      throw new IllegalStateException("Unexpected memory-disk conflict in tests, please use FileDocumentManager#reloadFromDisk or avoid VFS refresh", trace);
+    }
+    
     String message = UIBundle.message("file.cache.conflict.message.text", file.getPresentableUrl());
 
     final DialogBuilder builder = new DialogBuilder();