--- a/eric7/Testing/TestingWidget.py	Thu May 19 17:03:34 2022 +0200
+++ b/eric7/Testing/TestingWidget.py	Fri May 20 11:17:22 2022 +0200
@@ -731,7 +731,11 @@
         
         if self.__project:
             mainScript = self.__project.getMainScript(True)
-            coverageFile = os.path.splitext(mainScript)[0] + ".coverage"
+            coverageFile = (
+                os.path.splitext(mainScript)[0] + ".coverage"
+                if mainScript else
+                ""
+            )
         else:
             coverageFile = ""
         interpreter = self.__venvManager.getVirtualenvInterpreter(