partial closing — three-part test

If the persons exercising control over a plant that is being closed for antiunion reasons (1) have an interest in another business, whether or not affiliated with or engaged in the same line of commercial activity as the closed plant, of sufficient substantiality to give promise of their reaping a benefit from the discouragement of unionization in that business; (2) act to close their plant with the purpose of producing such a result; and (3) occupy a relationship to the other business which makes it realistically foreseeable that its employees will fear that such business will also be closed down if they persist in organizational activities, we think that an unfair labor practice has been made out.