In unit test mode, preserve stacktrace for import error messages (in one more place)

plugins/gradle/src/org/jetbrains/plugins/gradle/service/project/BaseProjectImportErrorHandler.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2013 JetBrains s.r.o.
+ * Copyright 2000-2017 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,6 +15,7 @@
  */
 package org.jetbrains.plugins.gradle.service.project;
 
+import com.intellij.openapi.application.ApplicationManager;
 import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.openapi.externalSystem.model.ExternalSystemException;
 import com.intellij.openapi.progress.ProcessCanceledException;
@@ -158,8 +159,11 @@ public class BaseProjectImportErrorHandler extends AbstractProjectImportErrorHan
     }
 
     final String errMessage;
-    if (rootCauseMessage == null) {
+    if (rootCauseMessage == null || ApplicationManager.getApplication().isUnitTestMode()) {
       StringWriter writer = new StringWriter();
+      if (rootCauseMessage != null) {
+        writer.write(rootCauseMessage + "\n");
+      }
       rootCause.printStackTrace(new PrintWriter(writer));
       errMessage = writer.toString();
     }