If you are using Notepad++ editor (like the tag of the question suggests), you can use the great “Find in Files” functionality.
Go to Search > Find in Files (Ctrl+Shift+F for the keyboard addicted) and enter:
- Find What =
(test1|test2) - Filters =
*.txt - Directory = enter the path of the directory you want to search in. You can check
Follow current doc.to have the path of the current file to be filled. - Search mode =
Regular Expression